We present recent results from a proof-of-principle laser-plasma acceleration experiment that reveal a unique synergy between a laser-driven and particle-driven accelerator: a high-charge laser-wakefield accelerated electron bunch can drive a wakefield while simultaneously drawing energy from the laser pulse via direct laser acceleration. This process continues to accelerate electrons beyond...
Conventional RF electron accelerators are limited by breakdown potentials to ~100 MeV/m. This poses significant economic and practical obstacles for the construction of new, high energy particle accelerators which can be used as advanced light sources, or as colliders to probe new fundamental physics regimes. Laser Wakefield accelerators (LWFAs), which can achieve acceleration gradients 1000...
Stable acceleration of high-quality beams is a critical task for the realization of a plasma-based, linear collider. However, in plasma accelerators, the acceleration of collider-relevant positron beams is challenging even conceptually. Recently, many new positron acceleration schemes have been proposed to overcome this issue. In this talk, we review the latest advances on plasma-based...
Exploiting the strong electromagnetic fields that can be supported by a plasma, high-power laser driven compact plasma accelerators can generate short, high-intensity pulses of high energy ions with special beam properties. By that they may expand the portfolio of conventional machines in many application areas. The maturation of laser driven ion accelerators from physics experiments to...
Plasma wakefield acceleration (PWA) channels are characterized by very high accelerating gradients and very strong focusing fields. We propose to employ these properties for effective production of low emittance high energy muon beams, consider muon beam dynamics in the PWFA cell and analyze various options and potential of the PWA-based muon sources.
We show the recent results of electron injection into the laser wakefield accelerators by interfering two intense, nearly colinear laser pulses in underdense plasma [1, 2]. In the experiment, electrons could be injected into either laser wakefields, or both, depending on the relative delay between two laser pulses’ arrival time to the interference point. Particle-in-cell simulations revealed...
Beam-driven plasma-wakefield accelerators offer significant potential as compact, high-gradient, high-quality accelerators, either as the basis of a future plasma-based facility or as an ‘after-burner’ stage appended to conventional accelerators to boost their peak energy. To maximise applicability of such devices, plasma-based accelerators must be capable of operating at repetition-rates...
Laser Plasma Accelerators (LPAs), harnessing gigavolt-per-centimeter accelerating fields, can generate high peak current, low emittance and GeV class electron beams paving the way for the realization of future compact free-electron lasers (FELs). Here, we report on the commissioning of the COXINEL beamline driven by the HZDR plasma accelerator and experimental demonstration of FEL lasing at...
Positron acceleration in plasma is a topic of interest for future applications of plasma-based linear colliders. At FACET, we investigated the acceleration of positrons in plasma under a variety of regimes including linear, non-linear, and hollow channel configurations. Over the course of these experiments, we observed the acceleration of plasma electrons captured in a positron beam-driven...
We report the development of a multileaf collimator (MLC) for charged particle beams, based on independently actuated tungsten strips which can selectively scatter unwanted particles. The MLC is used in conjunction with an emittance exchange beamline to rapidly generate highly variable longitudinal bunch profiles. The developed MLC consists of 40 independent leaves that are 2 mm wide and can...
One of the two long-term applications of plasma-based accelerators is to develop the fifth-generation light source such as a compact free electron laser (FEL), which requires the generation of ultrahigh brightness electron bunches [1]. Recently, self-amplified spontaneous emission (SASE) by bunches from both laser- and beam-driven plasma accelerators have been observed [2, 3]. If the drive...
The ongoing Plasma-driven Attosecond X-ray source experiment (PAX) at FACET-II aims to produce coherent soft x-ray pulses of attosecond duration using a Plasma Wakefield Accelerator [1]. These kinds of X-ray pulses can be used to study chemical processes where attosecond-scale electron motion is important. As a future upgrade to this concept, we investigate scaling to shorter soft X-ray...
The Argonne Wakefield Accelerator (AWA) is a beam test facility at Argonne National Laboratory. It consists of a 65 MeV L-band photoinjector beamline, 3 additional independent photoinjector beamlines, and multiple flexible experimental areas. Its program is composed of three research themes: (1) Advanced Accelerator Concepts (AAC), (2) Beam Manipulation, and (3) Beam Production. The AAC...
Traveling-wave electron acceleration (TWEAC) is an advanced laser-plasma accelerator scheme, which is neither limited by dephasing, nor by pump depletion or diffraction. Such accelerators are scalable to energies beyond 10 GeV without the need for staging and are candidates for future compact electron-positron colliders based on existing CPA lasers. TWEAC utilizes two pulse-front tilted laser...
We present the results of the Snowmass Implementation Task Force (ITF) analysis of future collider concepts. We consider both the environmental cost of construction (CO2 footprint per meter of tunnel) and the carbon footprint associated with collider power consumption. We discuss strategies to mitigate the power consumption of future high-energy colliders, such as energy recovery, and we...
We report on the injection of 35MeV electron bunches into a laser-driven plasma wakefield at the CLARA linear accelerator, Daresbury Laboratory, UK. In this initial proof-of-principle experiment, we observed the broadening of the energy spectrum of 6ps electron bunches injected into a plasma, demonstrating successful acceleration/deceleration of electrons within the wakefield. We discuss...
We show that uncontrolled phase fluctuations within an outer annulus of the near-field profile of a laser-wakefield drive pulse are primarily responsible for shot-to-shot fluctuations in the energy, charge, and pointing of wakefield-accelerated electrons. When a mask removes this unstable annulus, RMS fluctuations decrease by more than half without compromising average electron energy...
The ion channel laser (ICL) is an alternative to the free electron laser (FEL) that uses the electric fields in an ion channel rather than the magnetic fields in an undulator to transversely oscillate a relativistic electron beam and produce coherent radiation. The strong focusing force of the ion channel leads to a Pierce parameter more than an order of magnitude larger than the typical...
PIConGPU, like many other codes, is ready for the next Exascale supercomputers. Heterogeneous programming as the main ingredient enables effective use of these machines. Important challenges still ahead are timely analysis of large scale simulation data and complex workflows for multi-physics simulations and machine learning.
As experimental capabilities progress and high-repetition rate...
Next generation particle accelerators based on laser plasma interactions are a promising path towards achieving GeV gradients in small volumes, thus substantially reducing the size of accelerators needed for both frontier science and practical applications from materials science to medicine. These accelerators will require laser drivers with ultrashort pulses, joule energy levels and 10s kHz...
Two-color ionization injection is a promising method for realizing an all-optical, plasma photocathode. In this method, a nonlinear plasma wakefield is driven by a long-wavelength laser, and the ionization injection occurs using a second, high-intensity laser pulse with a short wavelength. Recent upgrades at the Accelerator Test Facility (ATF) of the Brookhaven National Laboratory has provided...
Ultrafast lasers play an increasingly critical role in the generation, manipulation, and acceleration of electron beams. Laser plasma accelerators enable order of magnitude improvements in accelerating gradient and promise compact tunable GeV electron beam sources, while novel photocathode systems permit fundamental advances in electron beam manipulation for accelerator and radiation...
When a high intensity electron beam is passed through a structured nano target, the solid-state density plasma created can support ultra-high accelerating gradients, on the order of 1-10 TeV/m. The similarly strong transverse focusing fields are expected to produce beams with small equilibrium emittance. Driving these extreme wakefields in the self-modulated regime requires high energy and...
We investigate electrostatic traps as a novel source of positron beams for accelerator physics applications. The electrostatic trap is a simple device that accumulates and cools positrons produced by a radioactive source. Using well-established techniques, the positron beam is cooled down to or below room temperature. The thermal beam emittance is an order of magnitude smaller than beams...
Lasers of sufficient intensity passing through a neutral gas will ionize the gas creating a plasma channel in its wake. A shock can propagate from this locally heated region through the created plasma and background gas, however the density of the plasma will determine the dynamics of the plasma. For collisional (high density) plasmas this can be modeled with a fluid code, however a kinetic...
As part of the Argonne 500 MeV short pulse Two Beam Wakefield Acceleration Demonstrator, several single cell X-band dielectric disk loaded accelerators (DDA) have been designed, fabricated, and tested at high power at the Argonne Wakefield Accelerator. The DDA should provide a short pulse (~20 ns) high gradient (>100 MV/m) accelerator while maintaining a reasonable r/Q and high group...
Recent progress of fundamental study on nonlinear inverse Compton scattering (ICS) will be reported. Experiment has been performed in Brookhaven National Laboratory Accelerator Test Facility. Counter collision of TW CO2 laser and 60-70 MeV electron beam having 300 pC of charge per pulse induce clear structure of nonlinear electrodynamics in X-ray radiation characteristics. In addition,...
Structured plasmas present myriad opportunities for acceleration and control of electron and positron beams for advanced concepts accelerators. Modeling these systems is challenging, owing to the orders of magnitude disparities in the spatiotemporal scale lengths between beam or laser and background plasma evolution. We discuss the application of the FLASH code, a publicly available MHD...
Inverse Compton scattering (ICS) from relativistic electron beams colliding with laser pulses can be used for relatively compact and affordable x-ray and gamma sources complementing conventional synchrotron light sources (SLSs). Several proposals have been put forward on converting electron accelerators to Inverse Compton Scattering (ICS) gamma sources. Different types of particle accelerators...
A method of decreasing the required footprint of linear electron accelerators and to improve their energy efficiency is utilizing short RF pulses (~9 ns) with Dielectric Disk Accelerators (DDA). A DDA is an accelerating structure that utilizes dielectric disks in its design to improve the shunt impedance. Two DDA structures have been designed and tested at the Argonne Wakefield Accelerator. ...
Plasma wakefield accelerators (PWFA) have demonstrated acceleration gradients of tens of GeV per meter. For injecting high-quality electron beams, a method called beam-induced ionization injection (B-III) is proposed. In this method, the drive beam field increases as its slice envelope oscillates to its minimum value due to the betatron oscillations and releases impurity plasma electrons that...
In nonlinear Thomson scattering, a relativistic electron reflects and reradiates the photons
of a laser pulse, converting optical light to x rays or beyond. While this extreme frequency
conversion offers a promising source for probing high-energy-density materials and
driving uncharted regimes of nonlinear quantum electrodynamics, conventional nonlinear
Thomson scattering has inherent...
The Hybrid Collaboration, a joint undertaking by HZDR, DESY, University of Strathclyde, LMU, and LOA, performed hybrid LPWFA experiments which utilize electron bunches from a laser wakefield accelerator (LWFA) as drivers of a plasma wakefield stage (PWFA) to demonstrate the feasibility of compact PWFAs serving as a test bed for the efficient investigation and optimization of PWFAs and their...
Plasma photocathodes aim for the tunable production of compact electron beams with normalized emittance and brightness many orders of magnitude better than conventional sources. Experimental realization of such beams would open numerous prospects for transformative plasma wakefield accelerator applications based on ultrahigh-brightness beams. Developing a plasma capable of high-gradient...
In a typical laboratory plasma, there are no native positrons, which complicates attempts to develop a laser-driven positron accelerator. High-power high-intensity lasers provide an attractive opportunity to create positrons directly from light. While most attention has been focused on the multi-photon process, the process that involves two gamma-rays, the linear Breit-Wheeler (BW) process,...
Shunt impedance is one of the most important parameters characterizing particle acceleration efficiency. It is known that RF losses are reduced at cryogenic temperatures. For example, a record high shunt impedance of 350 MΩ/m was demonstrated recently for all metal X-band accelerating structure, which is more than 2 times higher than that at room temperature. Here we present a novel hybrid...
Well known light emitting mechanisms (e.g. betatron radiation and non-linear Thomson scattering) are based on the motion of single-particles. Experiments demonstrated that these mechanisms can lead to the emission of bright radiation bursts, with frequencies extending up to the x-rays and beyond. These sources have intrinsic limitations: the electron velocity is always lower than the speed of...
A barrier to realizing a plasma-based XFEL is the energy chirp of the accelerated electron bunch. If such a chirp is not removed prior to extraction it is difficult to maintain bunch qualities during transport to the undulator stage, and the FEL performance will be degraded or inhibited entirely. The Trojan Horse (TH) injection method uses a plasma photocathode approach to release and trap...
Electron beam generated by an injector is often characterized by a set of parameters such as rms normalized emittance, bunch length, peak current, energy etc.. For different applications, the requirement for the beam parameters can be very different. In addition, some beam applications require finer control of the electron distribution such as specific shapes for its projection along a...
With accelerating gradients of tens of GeV/m, plasma accelerators have a great potential for replacing RF cavities in future colliders and FEL light sources. However, the beams generated by these accelerators need to satisfy stringent quality metrics before they can be considered for the aforementioned applications. One such metric is the relative energy spread ΔE/E, which needs to be at a...
The FACET-II facility at SLAC National Accelerator Laboratory conducts a broad science program based on the interaction of low-emittance high-current 10 GeV electron beams with lasers, plasmas and solids. FACET-II operates as a National User Facility while engaging a broad User community to develop and execute experimental proposals that advance the development of plasma wakefield...
Hosing of particle bunches [1] (or laser pulses) driving or experiencing wakefields in plasma may impose limits on the quality and efficiency [2] of the acceleration process. Understanding and measuring hosing is therefore important and interesting. We present an experimental study of hosing of a long proton bunch in plasma. We induce hosing with the relative misalignment between the...
In recent years Europe had an intense discussion on roadmaps for accelerator R&D and research infrastructures. Several roadmaps were published and prominently include advanced accelerators. Of particular visibility are the 2021 Roadmap Update of the government-led European Strategy Forum for Research Infrastructures (ESFRI) and the 2022 publication of the European Roadmap on Accelerator R&D...
Research of plasma-based accelerators has achieved significant milestones over the last decade. Highlights include achieving nearly 8 GeV electrons in a single-stage source, demonstrating plasma-based FELs, reaching stable proton acceleration of ultra-short, nC-class pulses that enable studies into ultrahigh dose rate radiotherapy. As the exploratory aspect of the field benefits significantly...
High brightness beams for XFELs and UEM essentially imply a high current and a low emittance. To obtain such beams we propose to raise the accelerating voltage in the gun mitigating repealing Coulomb forces. An ultra-high gradient is achieved utilizing a short-pulse technology. A successful experiment with an X-band photoinjector has been recently carried out at Argonne Wakefield Accelerator...
Recent experiments [1] have demonstrated acceleration of electron bunches up to 5 GeV in long (20 cm) low density (~10^17 cm^-3) ionization-injected plasma waveguides [2]. The spectra of the recorded electron bunches showed multiple quasi-monoenergetic peaks with resolution limited energy spreads ~15%. For eventual development of a 10 GeV laser wakefield acceleration (LWFA) module for a staged...
The E300 experiment at FACET-II aims to demonstrate energy doubling of a witness bunch to 20 GeV through beam-driven plasma wakefield acceleration (PWFA) while preserving emittance and narrow energy spread. This talk will describe the status of the experimental setup including the current and expected accelerator parameters, the plasma source and associated differential pumping system, and...
Radiation emission plasmas is often a result of collective effects associated with the dynamics of relativistic charged particles. A common numerical approach to model their motion involves the Particle-In-Cell scheme which solves the full set of Maxwell's equations and the relativistic Lorentz force for the charged particles.
The Radiation Diagnostic for OSIRIS (RaDiO) can retrieve the...
Practical use of laser plasma accelerators will require drivers with high peak power and high repetition rate. Spatially and temporally coherently combined fiber laser arrays offer one of the most promising pathways to such drivers. Temporal combining of ~100 stretched pulses, implemented as a coherent pulse stacking amplification (CPSA) technique [1], enables near-complete extraction of...
It has been recently shown that a high-current ultrarelativistic electron beam can undergo strong self-focusing due to the Near-Field Coherent Transition Radiation (NF-CTR) emitted when interacting with multiple submicrometer-thick conducting foils [A. Sampath et al., Phys. Rev. Lett. 126, 064801 (2021)]. Particle-In-Cell simulations show that this self-focusing phenomenon is accompanied by...
Laser-wakefield plasma accelerators (LWFA) promise compact sources of highly energetic electrons and photons, but for their practical use they need efficient and high repetition rate laser drivers. The current standard is the Ti:sapphire CPA system, which can produce multi-J pulses with bandwidths supporting ~30 fs pulses, but it has low wall plug efficiency (WPE) and ~Hz repetition rates....
The multi-pulse laser wakefield acceleration (MP-LWFA) scheme [1] provides a route for GeV-scale accelerators operating at kilohertz-repetition-rates driven by picosecond-duration laser pulses such as those available from thin-disk lasers. We recently published theoretical work proposing a new scheme of GeV accelerator based on MP-LWFA, which we call the Plasma-Modulated, Plasma Accelerator...
A program to develop a sub-GV/m rf photocathode gun is underway at Argonne Wakefield Accelerator (AWA) facility as a pathway towards producing brighter electron bunches. The X-band rf gun is powered by high-power, short rf pulses (9-ns FWHM), which, in turn, are generated by AWA’s high-current drive beam. In a previous proof-of-principle experiment, an unprecedented gradient of 400 MV/m on the...
A laser-plasma accelerator (LPA) could reach high energies with an accelerating length orders-of-magnitude shorter than in conventional RF accelerators. Compact LPAs will enable high-impact applications in science, medicine, security, and industry. As LPA applications will require new driver lasers with kHz to 10s kHz repetition-rates at high energy and efficiency [1], one promising laser...
The energy required to drive a large-amplitude plasma wave can be delivered over many plasma periods, rather than in a single period, if the driving pulse is modulated. This approach opens up plasma accelerators to novel laser technologies which can provide the required energy at high pulse repetition rates, and with high wall-plug efficiency. We recently proposed [PRL 127, 184801 (2021)] that...
Spatiotemporal control refers to a class of optical techniques for structuring a laser pulse with space-time dependent properties, including moving focal points, dynamic spot sizes, and evolving orbital angular momentum. These structured pulses have the potential to enhance a number of laser-plasma applications, including laser wakefield acceleration (LWFA) [1,2]. Here we introduce the concept...
Laser-plasma accelerators (LPA) can significantly reduce the large sizes of conventional accelerators, showing great potential, but they are challenged by today’s low operation repetition-rates (Hertz class). Achieving kilohertz repetition-rates is necessary to enable high impact applications in science, security, and medicine [DOE Basic Research Needs Workshop report, 2019].
One recognized...
Plasma lenses are of much interest to the plasma-accelerator community as their cylindrically symmetric and large focusing gradients facilitate beam-optics control of the highly divergent beams usually associated with plasma accelerators. However, a fundamental difference between plasma-based and conventional accelerators/focusing devices is that in the former the beams propagate through...
Multipactor discharges in dielectric accelerating structures are a major limitation on the performance of this otherwise very promising technology for future high energy physics machines and other applications. Multipactor occurs when the Secondary Emission Yield (SEY) of the dielectric material used in accelerating structures is significantly higher than 1. In this work, we evaluated the...
Relativistic ion beams have wide applications ranging from proton therapy, neutron beam/warm dense matter generation, and fast ignition of fusion pellets. In particular, generating a monoenergetic high energy flux ion beam is of great interest, since fast-ignition scheme of fusion targets require energy fluxes of ~GJ/cm^2. We show that a foam-based target with parabolically shaped front...
The extremely high electric fields sustainable by a plasma make the Laser Wakefield Acceleration (LWFA) the most compact technique to generate very highly relativistic electron beams up to the GeV regime. The limited repetition rate and low efficiency of this technology has, to date, prevented to unleash its full potential as a unique source for basic research, biomedical applications and high...
Plasma-driven light source development has recently made significant progress with multiple demonstrations of plasma-FEL gain [1-2] and the ongoing work of various facilities dedicated to plasma-FEL development [3]. In this contribution, we report on the status and prospects for one-such plasma-driven light source effort, the Plasma-driven Attosecond X-ray (PAX) experiment at FACET-II [4]....
Detailed thermal modeling of crystal amplifiers is a prerequisite for rapid improvement—higher pulse quality, higher average power at maximum achievable peak intensity, better repeatability, etc.—of high-intensity lasers ($100~\mathrm{TW}$ to multi-PW) with ultra-short pulse lengths ($< 100~\mathrm{fs}$). In recent work [1], we used the open-source, finite-element code FEniCS [2] to solve the...
Longitudinal bunch shaping based on transverse deflecting cavities (TDCs) was first proposed in Tech. Rep. No. LBNL-2670E, 2009 and further elaborated in Phys. Rev. Accel. Beams 23, 072803, 2020. Bunch shaping takes place in a straight beamline configuration of TDCs and a shaping mask. Two potential advantages of TDC-based shaping, over other shaping methods, is that it does not use dipole...
To date only solid-state laser pulses of wavelength 𝜆 ~ 1 micron have been powerful enough to drive laser wakefield accelerators (LWFAs). Chirped-pulse-amplified multi-terawatt, ~1 ps laser pulses of 𝜆 ~ 10 µm are now emerging from mixed-isotope, high-pressure CO$_2$ laser technology [1]. Such pulses open new opportunities to drive large ($R_b \sim 300$ µm) bubbles in low-density ($n_e <...
There is currently a lack of broadly available modeling software that self-consistently captures the required physics of gain, thermal loading and lensing, spectral shaping, and other effects required to simulate and optimize high-intensity lasers (100 TW to multi-PW) with ultra-short pulse lengths (< 100 fs) [1]. In recent work [2], we showed that low-resolution wavefront sensor (WFS) images...
Contact and projection electron radiography using a laser-plasma electron accelerator driven by the OMEGA-EP laser are shown for static targets. Initial electron radiographs of laser-driven foils are shown along with a discussion of future experiments and applications. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award...
RF breakdown and pulse heating are the greatest obstacles to increasing the accelerating gradient. Numerous experiments have shown that the RF breakdown and pulse heating thresholds depend on the exposure time of the structure to the RF fields. The idea described here is to accelerate particles by short (nanosecond or subnanosecond) duration wakefields in a structure assembled of individually...
We present the progress made toward a plasma wakefield accelerator using a laser-ionized, unconfined gas plasma source for the E301 experiment at FACET-II. One advantage of this plasma source is that the density profile can be semi-arbitrarily defined via controlled focusing of a terawatt class laser pulse, allowing for the creation of entrance and exit ramps that can match the beam into and...
Recently, a novel concept of Laser-Ion Lensing and Acceleration (LILA) [1] has been introduced for highly-efficient generation of monoenergetic low-emittance ion beams. The LILA scheme is based on the illumination of a solid-density target with radially-dependent thickness by an intense circularly polarized (CP) laser pulse, resulting in simultaneous acceleration and focusing of proton beams...
We aim to develop a diagnostic capable of high spatio-temporal resolution, specifically to be used in High Energy Density Science (HEDS) experiments. A Self-Modulated laser wakefield acceleration (SM-LWFA) driven broadband X-ray source was observed at the Titan target area, Jupiter Laser Facility. The spectral range was between 10 KeV to > 1 MeV, and took advantage of Betatron, Inverse Compton...
The study of laser wakefield acceleration (LWFA) using long wavelength infrared laser drivers is a promising path for future laser-driven electron accelerators when compared to traditional near-infrared laser drivers operating at $0.8-1$ $\mu\rm{m}$ central wavelength [1,2]. For a fixed laser intensity I, lasers with longer wavelengths $\lambda$ have larger ponderomotive potential ($\propto$...
With the commissioning of the 10 GeV FACET-II accelerator underway, early experimental shifts of the plasma lens have been taken. These shifts use a single electron bunch propagating through a laser-ionized elongated gas jet, with an electron beam imaging spectrometer set up to disperse the beam in energy for one transverse axis and image the beam directly in the other. Currently, a laser...
Laser-plasma accelerators (LPAs) operating in the bubble regime require driver lasers with relativistic intensities and pulse durations that are significantly shorter than the plasma wavelengths. This severely limits the laser technology that can be used to drive LPAs and with that their wide spread and the currently achievable LPA parameters, such as repetition rate. Here, we report a widely...
A laser pulse composed of a fundamental and properly phased second harmonic exhibits an asymmetric electric field that can drive a time-dependent current of photoionized electrons. The current produces a near-single-cycle burst of terahertz (THz) radiation. Experiments using ~1-TW ultrashort laser pulses observe optimal THz energies (~10-uJ) when the “two-color” pulse undergoes filamentary...
Fields arising during the propagation of highly intense electron beams in structured targets of nanometer scale such as carbon-nanotubes can contain accelerating gradients of up to 10 TV/m with similarly strong focusing fields. Studies of beam-nanotarget interaction are therefore of interest as they may lead to an acceleration method with extremely high single-stage energy gains for electron...
The goal of the E-324 experiment ("Optical visualization of e-beam-driven wakes") at SLAC's 2nd-generation Facility for Advanced Accelerator Science and Experimental Tests (FACET-II) is to observe and understand electron- and ion-density structures that arise during, and at delays up to ~ms after, e-beam-driven production of strongly nonlinear plasma wakefields. The current set-up...
We investigate electrostatic traps as a novel source of positron beams for accelerator physics applications. The electrostatic trap is a simple device that accumulates and cools positrons produced by a radioactive source. Using well-established techniques, the positron beam is cooled down to or below room temperature. The thermal beam emittance is an order of magnitude smaller than beams...
The generation and acceleration of an electron beam with a high degree of spin polarization is desirable for future plasma-based high-energy colliders. Our recent theoretical and simulations work [1,2] has shown that spin polarized electrons can be produced from photoionization of 4f14 electrons of Yb III ions by a circularly polarized laser, and then accelerated to multi-GeV energies while...
The discretization of electromagnetic equations of motion can lead to changes in the dispersion relations such that particle velocities can meet or exceed the effective speed of light, even in vacuum. Numerical Cherenkov Radiation results from a resonance response between the electromagnetic potentials and superluminal charge. To assess the effects of numerical Cherenkov radiation on...
Laser plasma accelerators have the ability to produce high-quality electron beams in compact, all-optical-driven configurations, with the electron beams uniquely suited for a wide variety of accelerator-based applications. However, fluctuations and drifts in the laser delivery to the mm-scale plasma target (the electron beam source) will translate into electron beam source variations that can...
Ultrafast high-brightness X-ray pulses have proven invaluable for a broad range of research. Such pulses are typically generated via synchrotron emission from relativistic electron bunches using large-scale facilities. Recently, significantly more compact X-ray sources based on laser-wakefield accelerated (LWFA) electron beams have been demonstrated. In particular, laser-driven betatron...
We present a novel all-optical streak camera (AOSC) based on the Kerr-effect which measures the relative temporal position of a laser pulse and a second short pulse of arbitrary constituents (e.g. electrons, protons, light, or x-rays) in a single shot. Many modern accelerator concepts rely on the coupling of an electron beam with a laser beam, which must overlap with ultra-high temporal...
We introduce a novel method of controlled electron injection for Laser Wakefield Acceleration (LWFA) operating in the high-intensity "bubble" regime. In this scheme, a fraction of a high-intensity "driver" pulse is diverted and compressed into a low power, few-cycle "satellite" pulse co-propagating alongside the driver. This satellite is tightly focused off-axis where it acts to perturb bubble...
We reconstruct the spectral cut-off of bremsstrahlung x-rays generated by GeV laser-wakefield-accelerated electrons with 10% accuracy using a compact, modular x-ray stack calorimeter. Unfolded cut-off energies range from 1GeV to 3GeV and increase in accuracy with increasing energy, opposite to the trend for conventional magnetic spectrometers. Consequently, bremsstrahlung cut-off calorimetry...
The CO$_2$ laser at the Accelerator Test Facility of Brookhaven National Laboratory is a unique source generating 2 ps-long, multi-TW pulses in the mid-IR regime. This rapidly evolving system opens an opportunity for generation of large bubbles in low density plasmas (~10$^{16}$ cm$^{-3}$) that are ideal for acceleration of externally injected electron beams. A new generation of diagnostic...
In the interaction of high-intensity lasers with over-dense plasmas, the hot electron population dictates system dynamics, driving ion acceleration and x-ray generation, and fast ignition, for example. The primary method for modeling these systems are particle-in-cell simulations (PIC), where macroparticles approximate the kinetics of a distribution of particles. A problem shared with...
Coherently combined fiber lasers are considered to be among the most promising pathways towards developing power and energy scalable drivers for laser plasma accelerators (LPA) and other applications of high-intensity laser-matter interactions. Coherent pulse stacking amplification (CPSA) technique is a time-domain coherent combining using Gires-Tournois Interferometers (GTI) of multiple...
Since its installation in 2012, the petawatt (PW) facility at the Berkeley Lab Laser Accelerator (BELLA) Center primarily focused on the optimization of single-stage GeV-energy laser-plasma accelerators (LPAs). Recently, the PW facility completed an upgrade to install a new second beamline (2BL) and experimental target chamber. The installation of the second beamline enables BELLA PW to...
With the availability of petawatt lasers, the space required to generate beams of electrons to GeV-levels by laser-plasma acceleration has reduced to that of the university laboratory [1]. However, measuring these electrons in the relatively compact space of a vacuum chamber that can be supported by the typical university laboratory is challenging, as it typically requires large magnets (peak...
Laser-driven (LD) ion acceleration has been explored in a newly constructed short focal length beamline at the BELLA petawatt facility (interaction point 2, iP2). For applications utilizing such LD ion beams, a beam transport system is required, which for reasons of compactness be ideally contained within 3 m. The large divergence and energy spread of LD ion beams present a unique challenge to...
Future colliders, such as the Electron Ion Collider (EIC) will require injector linacs to accelerate large electron bunches over a wide range of energies. Current designs are typically based around long travelling wave structures, where power is coupled on axis between cavities. We propose the use of a 1 m distributed coupling design as an efficient means of achieving high gradient...
This presentation will showcase the newest work to add to the SwissFEL light generation capabilities. Two sets of modulators within which an overlap between an optical laser and relativistic electron beam are being installed and tested to produce new soft x-ray pulse structures and seeded beams. The results from the installation and commissioning of the first structure, put into operation in...
We study the propagation of an electron bunch travelling within a proton bunch through a plasma density ramp. The proton bunch charge density in the ramp is higher than the plasma density. In this nonlinear regime the bunch generates a high density, on-axis plasma electron filament. The filament is defocusing the externally injected electron witness bunch that can therefore be lost along the...
We explore the possibility of self-guided CO2-laser driven wakefield accelerator with external injection from a linear accelerator. Since long-wavelength CO$_{2}$ laser pulse enables a lower power threshold for self-guiding, nonlinear LWFA at a lower plasma density with larger wakefield size can be achieved, making longer acceleration and external injection easier. We aim to find the optimal...
Measurements of Radio Frequency (RF) emission may be a useful diagnostic for electron dynamics in laser-plasma interactions. Such radiation can also be detrimental as a significant source of noise for other diagnostics. EMP measurements were made during interactions of high-power short-pulse lasers with gaseous density targets at the University of Michigan. In a nitrogen-doped helium target...
We present the latest experimental results using a dual grating dielectric laser accelerator (DLA) to modulate 6 MeV electrons. The structure is composed of two commercially available gratings, mounted independently with variable gap size controlled by 3 piezo motors. A 780 nm laser is used to drive the 800 nm periodic structure with gap size on the order of 1 um. These gratings are 4 mm long,...
Due to the oscillation and subsequent emission of synchrotron radiation of electrons accelerated to GeV-order energies over centimetre scales, laser wakefield accelerators (LWFAs) have produced x-ray beams with a peak spectral flux up to 104 photons/pulse/mrad$^{2}$/0.1% BW. In a recent experiment performed by Wood, J. et al., an f/40 parabolic mirror was used to focus a 100 TW laser pulse...
Laboratory working conditions and unproperly set experimental designs highly impact the instruments’ performance and shortens their life. Several studies have been conducted on the performance of optical components in ultrafast high-power lasers and metrology equipment. The work presented is a study of different types of damages observed on stretcher and compressor diffraction gratings used in...
The stability of the drive electron beam in plasma wakefield acceleration (PWFA) is critical for the realization of many applications. The growing instability of a drive electron beam can couple into the plasma wake and further impact the transverse dynamics of the witness beam, rendering the emittance and energy spread to grow. Applications like positron acceleration in an electron-driven...
X-ray induced Acoustic Computed Tomography (XACT) is an imaging modality that combines the high absorption contrast and penetration depth of x-rays with the 3D propagation advantages provided by high-resolution ultrasound waves. Absorbed x-rays in a sample cause a localized heating ($<$mK) and thermoelastic expansion inducing a detectable ultrasonic emission. Effective generation of sound...
Particle beams with highly asymmetric emittance ratios are employed at accelerator facilities and are expected at the interaction point of high energy colliders. These asymmetric beams can be used to drive wakefields in dielectric structures and can be used to drive high gradient wakefields in plasmas. In plasma, the high aspect ratio of the drive beam can create a transversely elliptical...
Plasma-based acceleration (PBA) is a promising approach for generating high quality ultrarelativistic beams to drive next-generation x-ray light sources and particle collider experiments. Over the years, research has largely focused on injection methods that use a density down ramp or field ionization to generate such beams. Recently, we proposed and demonstrated new methods of controllable...
Positron acceleration in plasma is a topic of interest for future applications of plasma-based linear colliders. At FACET, we investigated the acceleration of positrons in plasma under a variety of regimes including linear, non-linear, and hollow channel configurations. Over the course of these experiments, we observed the acceleration of plasma electrons captured in a positron beam-driven...
This presentation will report results of high gradient testing of two C-band accelerating cavities fabricated at Los Alamos National Laboratory (LANL). LANL has successfully commissioned a C-band Engineering Research Facility of New Mexico (CERF-NM) which now serves for testing accelerating cavities at C-band. The test stand is powered by a 50 MW, 5.712 GHz Canon klystron and offers a unique...
Potential applications for laser-driven x-ray sources benefit from operation at high repetition-rate. Here, 15 mJ CPA pulses are generated at 480 Hz repetition-rate and tightly focused onto a gas target for the generation of K$_\alpha$ x-rays from a number of noble gases. The continuously-flowing nature of the gas jet meant that the target density was below the threshold for clustering and...
We aim to develop a diagnostic capable of high spatio-temporal resolution, specifically to be used in High Energy Density Science (HEDS) experiments. A Self-Modulated laser wakefield acceleration (SM-LWFA) driven broadband X-ray source was observed at the Titan target area, Jupiter Laser Facility. The spectral range was between 10 KeV to > 1 MeV, and took advantage of Betatron, Inverse Compton...
Laser plasma accelerators can generate acceleration gradients of 10~100 GeV/m and have delivered multi-GeV electron beams. In a recent experiment, we demonstrated electron acceleration up to 5 GeV in a 20-cm plasma waveguide, formed via self-waveguiding pulses in a low density hydrogen gas jet [1,2]. The long optical guiding of multi-100 TW pulses causes complex evolution of the laser driver...
There is increasing interest in developing accelerator technologies for space missions, particularly for fundamental science. In order to meet these mission needs, key accelerator technologies must be redesigned to be able to function in a remote and harsh environment. In this work we focus on a modest electron injector system, specifically the traditional thermionic cathode. Typically such...
Plasma wakefield accelerators (PWFA) have demonstrated acceleration gradients of tens of GeV per meter. For injecting high-quality electron beams, a method called beam-induced ionization injection (B-III) is proposed. In this method, the drive beam field increases as its slice envelope oscillates to its minimum value due to the betatron oscillation and releases impurity plasma electrons that...
THz-frequency accelerating structures could provide the accelerating gradients needed for next generation particle accelerators with compact, GV/m-scale devices. Current THz accelerators are limited by significant losses during transport of THz radiation from the THz source to the acceleration structure. In addition, the broadband spectral properties of high-field laser-driven THz sources make...
A moderately high plasma density (>$10^{20}$ m$^{-3}$) with very high axial uniformity is needed to achieve wakefield acceleration of electrons in the GV/m range in AWAKE plasmas. While helicon plasmas are capable of reaching sufficient densities at the beginning of a 5 ms pulse, it is not known if they meet the strict uniformity requirement of 0.25% for use in AWAKE. Laser induced...
Meter scale plasma channels are a crucial component of plasma wakefield accelerators. Creating a meter-scale plasma requires distributing the energy of the laser over that length while maintaining a high local intensity along the channel. One method for generating such a channel is by using a method known as the “flying focus”. Flying focus uses a diffractive optic on a chirped laser pulse, so...
Measuring the amplitude of plasma wakefields is challenging. It is however essential for AWAKE [1], since the proposed self-modulation mechanism suggested to drive large amplitude wakefields [2] with a long particle bunch must be seeded to be reproducible in phase [3,4] and in amplitude. Also, the amplitude of the wakefields evolves significantly during the growth of the self-modulation...
The ongoing Plasma-driven Attosecond X-ray source experiment (PAX) at FACET-II aims to produce coherent soft x-ray pulses of attosecond duration using a Plasma Wakefield Accelerator [1]. These kinds of X-ray pulses can be used to study chemical processes where attosecond-scale electron motion is important. As a future upgrade to this concept, we investigate scaling to shorter soft X-ray...
The measurement and recording of terahertz (THz) electric fields is of special interest to beam physics, as the electric fields of temporally short relativistic electron bunches have frequency components that extend into the THz range. These frequency components are challenging to measure using conventional methods, as this range of frequencies are too high for electronic systems, and are too...
We present different possible ionization volumes/shapes inside a Plasma Wakefield to realize the Trojan Horse Injection method. Our all-optical setup uses tailoring of the laser near field to produce an adjusted laser focus profile and therefore an optimized ionization volume and state. Different initial beam profiles show different behaviors in our simulations hence we showcase various...
One of the Grand Challenges identified by the Office of High Energy Physic relates to the use of virtual particle accelerators for beam prediction and optimization. Useful virtual accelerators rely on efficient and effective methodologies grounded in theory, simulation, and experiment. Typically, virtual accelerators are created using either computationally expensive simulations or black box...
An intense laser pulse propagating inside a plasma can generate a plasma bubble that can trap, accelerate, and focus electrons. These plasma bubbles undulate transversely according to its Carrier-Envelope-Phase (CEP) when (1) it is a near-single-cycle (NSC) pulse or (2) it undergoes steepening and forms a shock-like front. We demonstrate how this effect can be harnessed to control injection...
We investigate the photoelectron spin characteristics when hydrogenic ions are centro-symmetrically irradiated with converging vector waves — a non-paraxial form of structured light. A photon with given total angular momentum $j$ and azimuthal mode number $m$ generates photoelectrons with both helicities, in contrast to the fixed helicity produced by left- or right circularly polarized light....
High-power long-wavelength infrared lasers (e.g. CO$_{2}$ laser) are of great interest for acceleration of electrons and ions. For LWFA, pulses as short as 300-500fs are required to drive relativistic plasma wakes at 10$^{16}$-10$^{17}$ cm$^{-3}$ densities. The shortest pulse length demonstrated so far in CO$_{2}$ lasers is 2ps; these multiterawatt pulses are generated using a multistage MOPA...
In a laser wakefield accelerator, the ponderomotive force of an intense laser pulse propagating through a plasma excites a large amplitude plasma wakefield that can trap and accelerate electrons to relativistic energies. To prevent the electrons from outrunning the accelerating phase of the wakefield, spatiotemporal pulse shaping can be used to propagate the laser intensity at the vacuum speed...
We present on the fabrication and testing of a 16-cell distributed coupling accelerator operating at 95 GHz. The π-mode standing wave cavities are designed with a side-coupled aperture that enables flexible optimization of the beampipe iris between cells. Simulations of the optimized cavity geometry predict a room temperature shunt impedance exceeding 400 MOhm/m. We also discuss techniques for...
High fidelity modeling of plasma based accelerators (PBA) requires the use of 3D, fully nonlinear, and kinetic descriptions based on particle-in-cell (PIC) method. Compared to the computationally intensive full 3D explicit PIC code, the quasi-static PIC codes are able to speed up the simulations by orders of magnitude, which allows for modeling the physical problems requiring massive computing...
The ongoing Plasma-driven Attosecond X-ray source experiment (PAX) at FACET-II aims to produce soft x-ray pulses of attosecond duration with TW peak power using a Plasma Wakefield Accelerator [1]. These X-ray pulses can be used to study chemical processes where attosecond-scale electron motion is very important.
For this first stage of the experiment, PAX plans to demonstrate that sub 100 nm...
Introducing a minimal numerical framework capable of simulating intense laser-plasma kinetic interactions. The Vlasov-Maxwell Hamiltonian system is naturally constrained to simulate driving-laser ponderomotive effects on electron and ion kinetics along the direction of laser propagation, without discarding the impact of the relativistic transverse momentum on longitudinal dynamics. Structural...
Recent experiments [1] have demonstrated laser wakefield acceleration (LWFA) of quasi-monoenergetic electron bunches with energy up to 5 GeV, bunch charge up to tens of picocoulombs, and beam divergence down to milliradians using 20 cm long, low density ionization-injected plasma waveguides [2] using 240 TW peak power laser drive pulses. We present 3D particle-in-cell simulation results that...
A method of decreasing the required footprint of linear electron accelerators and to improve their energy efficiency is utilizing short RF pulses (~9 ns) with Dielectric Disk Accelerators (DDA). A DDA is an accelerating structure that utilizes dielectric disks in its design to improve the shunt impedance. Two DDA structures have been designed and tested at the Argonne Wakefield Accelerator. ...
The optimal performance of XFEL photoinjectors requires laser pulses, typically in the ultraviolet (UV), with non-Gaussian temporal intensity profiles and durations on the order of 10s of ps at photon energies higher than common ultrafast laser systems[1]. Achieving temporal shaping at these durations is non-trivial due to the limited spectral content for transform-limited (TL) pulses and a...
Spatio-temporally synchronized light sources form the backbone of various laser plasma acceleration (LPA) experimental diagnostic tools including transverse shadowgraphy, schlieren imaging and interferometry. In common practice, electronic pulse picking or physical beam splitting are used to derive sources of synchronized ultrashort probe light from the high-power drive laser. Practical cavity...
High-impact laser plasma accelerators (LPA) applications such as scientific discovery, medical radiation therapy, industrial and security screening require LPAs operating at kilohertz repetition rates or higher while today’s LPAs are limited to a few Hertz repetition rates. We propose coherently combining short pulse fibers to achieve highly stabilized high energy ultrashort pulses at high...
Direct laser acceleration (DLA) is capable of generating super-ponderomotive energy electrons to hundreds of MeV, as well as secondary particles and radiation from high-intensity picosecond laser pulses interacting with underdense plasma. The dynamic and complex process of DLA is strongly dependent on a combination of plasma and laser parameters. Experiments performed on the OMEGA EP facility...
The ion channel laser (ICL) is an alternative to the free electron laser (FEL) that uses the electric fields in an ion channel rather than the magnetic fields in an undulator to transversely oscillate a relativistic electron beam and produce coherent radiation. The strong focusing force of the ion channel leads to a Pierce parameter more than an order of magnitude larger than the typical...
Smith-Purcell Radiation (SPR) is a special case of diffraction radiation produced when a charged particle passes just over the top of a grating surface. The wavelength of emitted radiation is dispersed as a function of angle and order. Laser Wakefield Accelerators (LWFAs) produce highly-energetic, temporally-short electron bunches that could provide an unusually strong, coherent, superradiant...
In previous work [1] we found that circularly polarized few-cycle pulses were more effective at accelerating low divergence, quasi-monoenergetic electron beams than their linearly polarized counterparts. These pulses were generated by sending initially elliptically polarized pulses which evolve to circular after propagation through a hollow core fiber differentially pumped with Helium and...
The application of ultrafast, high-peak power lasers for laser-driven plasma acceleration (LPA) can lead to more compact accelerators reaching sufficiently high-acceleration gradients and high particle beam energies. However, such accelerators often require tremendous electrical resources and modern commercial lasers often operate on wall-plug efficiencies less-than-30%. Coherently combined...
A barrier to realizing a plasma-based XFEL is the energy chirp of the accelerated electron bunch. If such a chirp is not removed prior to extraction it is difficult to maintain bunch qualities during transport to the undulator stage, and the FEL performance will be degraded or inhibited entirely. The Trojan Horse (TH) injection method uses a plasma photocathode approach to release and trap...
Brookhaven Laboratory Accelerator Test Facility has a long history as a training site for graduate and undergraduate students. Young professionals are working on experiment setup during the active phases of the user program and assist engineers in design, build and repair of equipment during shutdowns.
Stony Brook University Center for Accelerator Science and Education and City University of...
With the commissioning of the 10 GeV FACET-II accelerator underway, early experimental shifts of the plasma lens have been taken. These shifts use a single electron bunch propagating through a laser-ionized elongated gas jet, with an electron beam imaging spectrometer set up to disperse the beam in energy for one transverse axis and image the beam directly in the other. Currently, a laser...
Snowmass is the name for a decadal planning exercise by the US high particle physics community. It provides an opportunity for the entire particle physics community to come together to identify and document a scientific vision for the future of particle physics in the U.S. and its international partners. The Snowmass exercise takes roughly a year (2 years including the impact of Covid) and...
Snowmass Accelerator Frontier topical group # 6, Advanced Accelerator Concepts (https://doi.org/10.48550/arXiv.2208.13279), covered new R\&D concepts for particle acceleration, generation, and focusing at ultra high acceleration gradients (GeV/m and beyond). Leveraging these to efficiently harness the interaction of charged particles with extremely high electromagnetic fields at very high...
Discussion of the AAC Vision and Future
Panel: Tor Raubenheimer, Vladimir Shiltsev, Cameron Geddes, Pietro Musumeci, Mark Hogan, and LK Len
The advanced accelerator community is well familiar with high-risk initiatives, which has led to multi-decade development programs before concepts are realized. What is less obvious is that building an accelerator company requires continuous development on a similar time scale, and is not entirely dissimilar in nature. RadiaBeam was spun off in 2004 from UCLA's advanced accelerator laboratory,...
Most of the ion acceleration experiments have been carried out with multi-cycle, Joule-class lasers in the TNSA and RPA regime. The recent developments of few-cycle laser systems with 100 W average power created the technological basis for the generation of ion current of tens of microA consisting of ultrashort particle bunches– something that many applications dream of. Here we present an...
The presentation will discuss advancements and new concepts on the topic of THz generation by 3-d printed structures in relativistic electron beams. A new concept has been developed that would greatly increase the efficiency of THz light generation, as well as allow for greater possibilities for control of the properties of the so generated Thz light. Wavelength, collimation and possibly pulse...
The upgraded Facility for Advanced Accelerator Experimental Tests (FACET-II) at SLAC has started delivering the first electron beams for the initial phase of several experimental campaigns hosted at the facility. During these first runs, the users have been able to test and commission different elements of their set-up, but also to obtain preliminary data to characterise the experimental...
The newly commissioned short focal length, high intensity beamline, named iP2, at the BELLA Center enables frontier experiments in high energy density science. This 1 Hz system provides a focused beam profile of <3 micron in FWHM, resulting in an on-target peak intensity greater than 5e21 W/cm^2 , and a pointing fluctuation on the order of 1 micron. A temporal contrast ratio of <1e-14 on the...
We report on experiments investigating the influence of spatio-temporal couplings (STCs) in the laser focus on stimulated Raman Side Scattering. We find a discrepancy between measured scattered angles and classical theory. At the same time, the angle changes with propagation of the driving laser pulse. This mismatch can be resolved if the pulse front tilt (PFT) of the laser pulse is taken into...
ARES is a linear particle accelerator at Deutsches Elektronen-Synchrotron DESY capable of producing high-quality, low-emittance electron beams dedicated to accelerator research and development. As an introduction we will present the achieved and projected performance of the ARES linac. An overview of the research activities on ultra-short electron bunch diagnostic methods, electron imaging and...
Characterizing the phase space distribution of particle beams in accelerators is a central part of accelerator understanding and performance optimization. However, conventional reconstruction-based techniques either use simplifying assumptions or require specialized diagnostics to infer high-dimensional (> 2D) beam properties. In this work, we introduce a general-purpose algorithm that...
After a decade-long successful operations [1] and producing new results in the field of Laser Plasma Acceleration (LPA) research [2-4] by the Berkeley Lab Laser Accelerator (BELLA), the PW laser system’s recent upgrades were completed in 2022. The first is the “Second Beamline” (PW-2BL), where the fully amplified, stretched pulses are split before compression, enabling two independently...
We present the latest experimental results using a dual grating dielectric laser accelerator (DLA) to modulate 6 MeV electrons. The structure is composed of two commercially available gratings, mounted independently with variable gap size controlled by 3 piezo motors. A 780 nm laser is used to drive the 800 nm periodic structure with gap size on the order of 1 um. These gratings are 4 mm long,...
The Near-Field Coherent Transition Radiation (NF-CTR) generated in the passage of an intense, highly compressed electron beam through a foil produces surface fields that can provide a strong self-focusing force back on the beam itself, and the intense emission of gamma-rays by the beam. This self-focusing effect can be enhanced by passing the beam through multiple foils of order micrometer...
High-brightness electron photoinjectors and electron linacs are fundamental to many advanced accelerator concepts and associated applications (see e.g., Ref. [1] and references therein). The industrial, medical and homeland security markets for low-to-moderate energy electron linacs are growing rapidly. To meet the design challenges for these divergent applications, with modest software...
The petawatt (PW) facility at Berkeley Lab Laser Accelerator (BELLA Center) has successfully performed several experiments since its installation in 2012 [1], primarily focusing on optimization of single stage, high energy gain laser-plasma accelerators (LPAs) [2,3]. Recently, the facility has undergone two significant upgrades: i) a new second beamline (2BL) delivered into the existing...
Many potential applications of plasma accelerators - such as light sources and future particle colliders - require the stable generation of multi-GeV electron bunches at high (>kHz) repetition rate. A consequent goal for current research into laser-driven plasma accelerators involves the development of waveguides capable of operating at densities of ~1017 cm-3, over...
PV/m plasmonics model pioneers extreme plasmons where the free electron Fermi gas constituted by the conduction band electrons in condensed matter is excited to its ultimate limits. Here we discuss novel physical mechanisms that begin to dominate the physics of extreme plasmons. For instance, relativistically induced ballistic electron transport helps explain earlier beam-metal interaction...
This talk will report on the status C-band high gradient research program at Los Alamos National Laboratory (LANL). The program is being built around two test facilities: C-band Engineering Research Facility in New Mexico (CERF-NM), and Cathodes And Radio-frequency Interactions in Extremes (CARIE). Modern applications such as X-ray sources require accelerators with optimized cost of...
Relativistic beam-plasma instabilities play a crucial role in high-energy astrophysical sources, such as gamma-ray bursts or blazars, in particular to create the electromagnetic turbulence responsible for the synchrotron emission of accelerated particles in these sources. These instabilities are also important in certain experimental concepts of particle accelerators or ultra-intense photonic...
For the creation of matter-antimatter pairs from the quantum vacuum via the Breit-Wheeler effect, an intense laser and energetic γ-rays need to interact with each other. At the Stanford Linear Accelerator Center the Breit-Wheeler experiment in the perturbative regime has been accomplished in 1997 but was not yet implemented in the non-perturbative regime, where the laser strength parameter...
Several new, high efficiency, RF sources are available or in development at frequencies from 325 MHz to 1.3 GHz and higher. If successfully developed, these new devices will represent lower cost alternatives to conventional RF sources. The primary focus is RF power production at higher efficiency and lower cost than currently available from conventional vacuum electron devices and solid-state...
The goals of plasma-based acceleration (PBA) are high gradient, high efficient acceleration and high quality beam generation. Various synchronized injection schemes utilizing PBA have been proposed and investigated to generate beams capable of driving a compact x-ray free electron laser (XFEL). In each of these ideas, the main challenge is how to maximize the energy transfer to the injected...
Hydrodynamic [1,2] and conditioned hydrodynamic [3,4] optical-field-ionised plasma channels are promising candidates to support low-density, high repetition-rate multi-GeV laser wakefield accelerator (LWFA) stages. They are generated by focusing an ultrashort pulse into neutral gas, forming a hot column of plasma via optical field ionization, which expands hydrodynamically to form a plasma...
Recent commissioning of the second laser pulse transport line at the BELLA PW facility enables strong-field quantum electrodynamics (SF-QED) experiments where an intense laser pulse collides with a GeV-class laser-wakefield-accelerated electron beam. An overview of the upgraded BELLA PW facility with a SF-QED experimental layout is presented. According to the simulation results these...
The future of high energy colliders beyond the high luminosity upgrade to the LHC is presently unclear. Physics and economics arguments are being made for hadrons vs. leptons and circular vs. linear machines. A muon collider is now being considered in Europe as a potential Future Circular Collider at CERN. Among the technological challenges inherent to a muon accelerator are beam cooling...
We study the generation of spatiotemporal optical vortices (STOVs) from self-focusing processes in plasma and their role in mediating intrapulse energy transport in intense, self-guided laser pulses using fully three-dimensional, particle-in-cell simulations.
In previous work, STOVs were observed both in experiment and in simulation to emerge from self-focusing collapse arrest from...
Beam driven plasma wakefield acceleration (PWFA) has shown the ability to accelerate electron beams with high acceleration gradients ~50 GeV/m, high efficiency, and low energy spread. This has inspired future linear collider (LC) designs where witness beams are accelerated over a series of plasma stages. In the LC regime, the witness beam emittance is ~100 nm and the charge is ~1 nC. With...
The petawatt-class multi-Hz Ti:Sa laser ALEPH developed at Colorado State University has recently enable major advances in laser wakefield acceleration [1]. However, progress on laser driven-particle accelerators for applications depends on the development of compact, more efficient lasers capable of producing of high energy ultrashort laser pulses at greatly increased high repetition rate. A...
Preserving the emittance of an electron bunch as it is accelerated by a plasma wakefield accelerator is one of the major challenges that needs to be overcome for these accelerators to replace conventional techniques. Energy spread in the bunch primarily drives the emittance growth through the process of chromatic phase spreading. The chromatic effects are complicated by the acceleration...
Increasing the proton beam energy from the present 800 MeV to 3 GeV will improve the resolution of the Proton Radiography Facility at the Los Alamos Neutron Science Center (LANSCE) by a factor of 10. It will bridge the gap between the existing facilities, which covers large length scales for thick objects, and future high-brightness light sources, which can provide the finest resolution....
Exascale computing is close to becoming a reality. As technology progresses, it has become clear that heterogeneous computing is going to stay and adapting to new hardware is an ongoing challenge. Since 2015 PIConGPU has paved the way to accelerating plasma simulations across compute platforms using the Alpaka framework. This has enabled early adaption to new compute hardware and readiness for...
The phase and growth rate of the self-modulation of a long proton bunch in over-dense plasma can be controlled by a preceding charged particle bunch. In order to selectively seed the growth of the proton bunch self-field, the dominance of seed over any undesired imperfections of the proton bunch is important. In this work, we investigate analytically and numerically the phase and growth rate...
Modeling plasma wakefield accelerators is computationally challenging. Using the quasi-static approximation allows for efficient modeling of demanding plasma wakefield accelerator scenarios. Here, the latest highlights of the performance-portable, 3D quasi-static particle-in-cell (PIC) code HiPACE++ are presented. HiPACE++ demonstrates orders of magnitude speed-up on modern GPU-equipped...
Stochastic Cooling is a feedback system for cooling particle beams in storage rings which uses radiation produced by the beam to correct the average deviation of temporal slices with a duration inversely proportional to the bandwidth. Optical Stochastic Cooling (OSC) uses optical wavelengths which decreases the duration of each slice and, therefore, reduces the incoherent noise each individual...
High peak power laser systems with architectures that are scalable in average power are essential to drive the next generation of advanced, compact electron accelerators. For this purpose, the Big Aperture Thulium (BAT) laser concept is designed to simultaneously operate at PW-class peak powers and multi-100kW average powers through the use of an energy extraction regime that scales in...
Several setups have recently been proposed to generate ultra-short laser pulses in the 10-100 as range with high energies (0.1-10 J) and a wavelength in the EUV-X range (1-100 nm), either by broadening the spectrum of near-infrared laser pulses to obtain single-cycle pulses that can be converted to single cycle attosecond pulses by a plasma mirror, or by directly using Doppler-boosted...
The Trojan Horse experiment has recently demonstrated the plasma photocathode concept at SLAC FACET, with a two-gas mixture where on species is ionized for wakefield generation and the other for precision witness beam generation within the plasma bubble. In an experimentally similar approach called the 'Dielectric Trojan Horse', the plasma accelerator component is replaced with a solid-state...
Increasing energy of proton beam at the Los Alamos Neutron Science Center (LANSCE) from 800 MeV to 3 GeV will improve radiography resolution ~10 times. This energy boost can be achieved with a compact cost-effective linac based on normal conducting high-gradient (HG) RF accelerating structures. Such an unusual proton booster is feasible for proton radiography (pRad), which operates with short...
The electromagnetic Particle-In-Cell (PIC) code WarpX has been developed within the the U.S. Department of Energy’s Exascale Computing Project toward the modeling of plasma accelerators for future high-energy physics colliders on Exascale Supercomputers. We will present the latest multi-GPU capable physics features, such as a Coulomb collision module and a QED module. We will also report on...
The long wavelength of long-wave infrared (LWIR) lasers suit them to applications relying on ponderomotive interactions, such as laser wakefield acceleration and high harmonic generation. The workhorse source of such wavelengths is the CO2 amplifier, providing the ability to reach TW peak powers and sub-ps pulse lengths. Two pathways to improve the performance of these amplifiers are to...
A new paradigm of extreme plasmonics unearthed by our work opens the unprecedented possibility of PetaVolts per meter fields that make it possible to access 1,000,000 times the acceleration gradient in RF accelerators. Plasmonic accelerators and light-sources put forth in our work rely on these extreme plasmons over timescales where the ionic-lattice remains largely unperturbed. A specific...
Adopting a recently developed simplified model of the impact of a very short and intense laser pulse onto an inhomogeneous diluted plasma, we analitycally derive preliminary conditions on the input data (initial plasma density $\widetilde{n_0}$ and pulse profile) allowing to control the wave-breaking of the laser-driven plasma wakefield and to maximize the energy transfer to small bunches of...
Laser plasma accelerators (LPAs) are capable of producing electron bunches as short as a few femtoseconds at percent-level energy spread. However, measuring the bunch length is not straightforward, let alone unraveling source correlations between the longitudinal position and momentum distribution. Here we present the theoretical framework and preliminary experimental demonstration of a...
The possibility of exciting wakefields in a semi-conducting structure is discussed. The fundamental limitation of short mean free paths of electrons in the semi-conductor can be overcome above a threshold beam or laser driver intensity when the electrons are driven to sufficient velocities that their Coulomb collision cross-section drops precipitously. The wakes differ from those in either a...
Multiple advanced accelerator concepts such as electron and ion acceleration from plasmas, inverse FEL’s, and Compton sources would benefit from the development of high-repetition-rate and short-pulse but high-energy mid-IR lasers. However, this intense-field mid-IR is still extremely difficult to access, since solid-state laser sources in this spectral region are limited in power. CO2 lasers...
The stability of the drive electron beam in plasma wakefield acceleration (PWFA) is critical for the realization of many applications. The growing instability of a drive electron beam can couple into the plasma wake and further impact the transverse dynamics of the witness beam, rendering the emittance and energy spread to grow. Applications like positron acceleration in an electron-driven...
An Eulerian finite-difference method solving the Vlasov equation is developed with a static, non-uniform momentum grid. The computational cost of this transformation differs negligibly from the uniform case with the same number of grid points. A general grid parametrization is tested against classic instabilities and driven cases and is found to provide significant efficiencies over the...
A new concept for a high-power L-band RF amplifier is described, namely a Two-Stage Multi Beam Klystron (TS-MBK) operating with 12 hollow beamlets. This configuration allows for a remarkably high RF electronic efficiency of up to 90%, with a compact electro-mechanical layout. We present a conceptual design for a 1.0 GHz, 20 MW peak-power TS-MBK; its predicted performance was determined using...
Reliable and versatile diagnostic methods are essential for modern accelerator facilities to successfully experiment with energetic particle bunches. Conventionally, an expansive network of tools is implemented in and around interaction points for optimization of experimental conditions; this is true for plasma-based accelerator experiments, with added restrictions to intercepting diagnostics...
We report on a single-shot longitudinal phase-space reconstruction diagnostic for an electron beam in a laser wakefield accelerator via the experimental observation of distinct periodic modulations in the angularly resolved spectrum. Such modulated angular spectra arise as a result of the direct interaction between the ultra-relativistic electron beam and the laser driver in the presence of...
Numerical modeling of electromagnetic waves is a critical component of particle-in-cell simulation of laser–plasma interactions. Traditionally, laser pulses have been either launched from simulated antennas or initialized in their entirety in the computational domain. Relying on the electromagnetic field update to advance the laser pulse, however, imposes needless computational expense and...
Laser Wakefield Acceleration (LWFA) is a process by which high gradient plasma waves are excited by a laser leading to the acceleration of electrons. The process is highly nonlinear leading to difficulties in developing 3 dimensional models for a priori, and/or ab initio prediction.
Recent experiments at the Rutherford Appleton Laboratory’s (RAL) Central Laser Facility (CLF) in the United...
Solutions of the single-particle equations of motion for electrons in the fields of an idealized TE111 microwave cavity in an external magnetic field near cyclotron resonance show acceleration rates that substantially exceed the limits for the CARA interaction. We have dubbed this new accelerator “eCRA.” Here, results are presented for realistic TE111 eCRA cavity geometry and finite...
A method to reconstruct the transverse self-wakefields acting on a beam, based only on screen images, is introduced. By employing derivative-free optimization, the relatively high-dimensional parameter space can be efficiently explored to determine the multipole components up to the desired order. This technique complements simulations, which are able to directly infer the wakefield...
By using the spinor representation of four-vectors, it is possible to write a simple expression for the momentum change of a charged particle in an arbitrary crossed field. It can be evaluated exactly if transcendental function evaluations are tolerable, or in an invariant-preserving expansion otherwise. We discuss progress in incorporating this approach into a particle-in-cell framework.
Particle beams with highly asymmetric emittance ratios are employed at accelerator facilities and are expected at the interaction point of high energy colliders. These asymmetric beams can be used to drive wakefields in dielectric structures and can be used to drive high gradient wakefields in plasmas. In plasma, the high aspect ratio of the drive beam can create a transversely elliptical...
The ATF's long-wave infrared (LWIR) laser produces optical pulses that enable substantially different acceleration regimes compared to near-infrared lasers. A 2 ps pulse duration and 5 TW peak power at 9.2 μm are presently the best demonstrated performance of this laser. This is achieved via chirped-pulse amplification of a microjoule seed pulse in a series of two high-pressure, mixed-isotope...
We have conducted experiments at the JeTi-200 laser facility ($\lambda_0=800nm$, spotsize $w_0=22\mu m$, pulse length $\tau=23 fs$, $a_0 = 2.4$) to investigate the contribution of laser polarization and carrier envelop phase (CEP) -fluctuations on the electron beam pointing jitter in laser wakefield accelerators(LWFAs). Furthermore, we developed a theory describing the transverse dynamics of...
An efficient numerical algorithm for multi-level ionization of high-atomic-number gases has been developed. It is based on analytical solutions to the system of differential equations describing evolution of ionization states. The algorithm fully resolves multiple time scales associated with ionization processes coupled to electromagnetic processes of laser-plasma interaction. The effects of...
Plasma wakefields produced by high-charge electron bunches are attractive for lepton colliders because they combine high-gradient acceleration and, in the regime of full electron blowout, emittance preserving linear focusing of the accelerated electrons by the remaining positively charged ions. Achieving the same for positrons is more challenging because it requires producing a uniform...
We present EZ, a novel Current Deposition algorithm for particle-in-cell simulations, which calculates the current density on the grid due to macro-particle motion within a time step by solving the electrodynamic continuity equation. Being a charge conserving hybridization of Esirkepov’s method and ZigZag, we refer to it as “EZ” as shorthand for “Esirkepov meets ZigZag”.
The talk will detail...
Colliding pulse injection of electron beams into a laser plasma accelerator (LPA), thus producing compact, stable, and monoenergetic electron beams, has important applications for narrow bandwidth Thomson gamma ray sources and novel x-ray free-electron lasers. The colliding laser pulses are independently optimized in terms of energy, beam size, and pulse compression. The spatiotemporal...
C3 – the Cool Copper Collider – is a concept for a e+e− Higgs factory at 250 GeV center of mass, with a potential upgrade to 550 GeV in the same footprint. C3 leverages novel advancements in high-gradient cryogenic copper accelerator structures which operate with high rf to beam efficiency. The C3 main linac requires significant R&D effort for the rf and cryogenic systems, beam delivery, and...
Attosecond science has emerged as a major research direction in X-ray free-electron laser science. X-ray free-electron lasers can routinely generate attosecond pulses with a peak power in the tens to hundreds of GW and are employed for time-resolved experiments with sub-fs resolution.
Plasma-based injectors have the potential revolutionize ultrafast science thanks to their ability to...
Laser-Plasma Wakefield Acceleration
Computation for Accelerator Physics
Laser and High-Gradient Structure-Based Acceleration
Beam Sources, Monitoring, and Control
Laser-Plasma Acceleration of Ions
Radiation Generation and Advanced Concepts
Advanced Laser and Beam Technology and Facilities
