Dr
Mark Palmer
(Cornell University)
10/8/10, 9:30 AM
Dr
Katherine Harkay
(Argonne National Laboratory)
10/8/10, 9:35 AM
Oral Sessions
Dr
Miguel Furman
(Lawrence Berkeley National Laboratory)
10/8/10, 11:15 AM
Prof.
Gerald Dugan
(Cornell University)
10/8/10, 2:15 PM
Dr
Mauro Pivi
(SLAC National Accelerator Laboratory)
10/8/10, 4:00 PM
Prof.
Maury Tigner
(Director, Cornell Laboratory for Accelerator-based Sciences and Education)
10/9/10, 9:10 AM
Dr
Robert Macek
(LANL and TechSource, Inc.)
10/9/10, 9:30 AM
Oral Sessions
Recent beam studies have focused on two aspects of the observed e-p instability at the Los Alamos Proton Storage Ring (PSR). 1) Most recently it has been observed that a stable beam with the standard production bunch width (290 ns injected beam bunch width) will become e-p unstable when the bunch width is shortened to 200 ns or less. This was not the case years earlier. Experimental...
Dr
Robert Zwaska
(Fermilab)
10/9/10, 10:00 AM
Oral Sessions
Using the new measurement station in the Main Injector, we have made a series of ECloud measurements in 2009 and 2010. The installation included Titanium-Nitride (TiN) and amorphous carbon coated beam pipes; these materials were directly compared to an adjacent stainless chamber through measurement with Retarding Field Analyzers (RFAs). Over the long period of running we were able to observe...
Christina Yin Vallgren
(CERN)
10/9/10, 11:00 AM
Oral Sessions
Amorphous carbon (a-C) thin films, produced in different coating configurations by using d.c magnetron sputtering, have been investigated in laboratory for low secondary electron yield (SEY) applications. After the coatings had shown a reliable low initial SEY, the a-C thin films have been applied in the SPS and tested with LHC type beams. Currently, we have used a-C thin film coated in...
Dr
Sara Casalbuoni
(Karlsruhe Institute of Technology)
10/9/10, 11:30 AM
Oral Sessions
Preliminary studies performed with the cold bore superconducting undulator installed in the ANKA (Angstrom source Karlsruhe) storage ring suggest that the beam heat load is mainly due to the electron wall bombardment. Electron bombardment can both heat the cold vacuum chamber and induce an increase in the pressure because of gas desorption. In this contribution we compare the measurements of...
Theo Demma
(INFN LNF)
10/9/10, 12:00 PM
Oral Sessions
A strong horizontal instability limiting the positron current has been observed at DAFNE since the installation of the FINUDA detector in 2003. Experiments and simulations seem to provide an evidence that the electron cloud build-up in the wigglers and bending magnets of the DAFNE positron ring induces a coupled bunch instability with features compatible with observations . To better...
Joseph Calvey
(LEPP, Cornell University)
10/9/10, 4:30 PM
Over the course of the CesrTA program at Cornell, over 30 Retarding Field Analyzers (RFAs) have been installed in the CESR storage ring. These devices, which measure the local electron cloud density and energy distribution, have been deployed in drift, dipole, quadrupole, and wiggler field regions. They can be used to evaluate the efficacy of cloud mitigation techniques in each magnetic...
Dr
Ady Hershcovitch
(Brookhaven National Laboratory)
10/9/10, 5:00 PM
Dr
Roberto Cimino
(LNF-INFN)
10/9/10, 5:30 PM
A common effort in most of the accelerator centers is to develop new technologies to produce and test beam pipe inner walls of particle accelerators with an as low as possible Secondary Electron Yield (SEY). This item, in fact, is crucial in controlling Electron Cloud formation and in reducing its effects, that are well known to be a potential bottle-neck to the performances obtainable...
Dr
Claudio Rivetta
(SLAC National Accelerator Laboratory)
10/10/10, 9:30 AM
Oral Sessions
Electron cloud driven instability can impose limitations on the maximum stored beam current in present and future accelerators. It drives inter-bunch and intra-bunch instabilities. Feedback control techniques have been proposed to mitigate transverse instabilities within a bunch as an extension of techniques used to control inter-bunch (coupled-bunch) instabilities.
The US LHC Accelerator...
Jean-Luc Vay
(LBNL)
10/10/10, 10:00 AM
Oral Sessions
Electron clouds impose limitations on current accelerators that may be more severe for future machines, unless adequate measures of mitigation are taken. Recently, it has been proposed to use feedback systems operating at high frequency (in the GHz range) to damp single-bunch transverse coherent oscillations that may otherwise be amplified during the interaction of the beam with ambient...
RAFFAELLO SECONDO
(LBNL)
10/10/10, 10:30 AM
Oral Sessions
The performance of High Energy proton machines like the SPS at CERN is affected by transverse single-bunch instabilities due to the Electron Cloud effect. In a first step to model a Feedback control system to stabilize the bunch dynamics, we use a Finite Impulse Response filter to represent the processing channel. The effect of this simplified processing channel in the bunch dynamics is...
Gerry Dugan
(Cornell University)
10/10/10, 11:30 AM
Oral Sessions
This talk will review recent data and simulation results related to electron-cloud induced beam dynamics studies at Cesr-TA.
Dr
John Flanagan
(KEK)
10/10/10, 12:00 PM
Oral Sessions
Measurements have been made of the bunch size and position along the train in electron cloud conditions at CesrTA. Preliminary results show a bunch size blow-up starting partway down the train, with the threshold bunch position moving forward at higher bunch currents, as would be expected for electron-cloud blow-up. The bunch-by-bunch beam profile and position data, and their Fourier power...
Dr
kazuhito ohmi
(kek)
10/10/10, 12:30 PM
Oral Sessions
We discuss single bunch instability in low emittance rings, especially focus
side band appearance.
Multi-bunch instability due to electron cloud in bending field is discussed.
Mr
Michael Billing
(CLASSE)
10/10/10, 3:30 PM
Poster
During the last several years CESR has been studying the effects of electron clouds on stored beams in order to understand their impact on future linear-collider damping ring designs. One of the important issues is the way that the electron cloud alters the dynamics of bunches within the train. Techniques for observing the dynamical effects of beams interacting with the electron clouds have...
Mr
Nathan Rider
(Cornell)
10/10/10, 3:30 PM
Poster
The research focus of the CESR Test Accelerator program requires new instrumentation hardware, software and techniques in order to accurately investigate beam dynamics in the presence of electron cloud effects. These new instruments are also required to develop low emittance beam conditions which are key to the success of the damping ring design for the International Linear Collider. This...
Mr
David Rubin
(Cornell University)
10/10/10, 3:30 PM
Poster
Low emittance tuning and characterization of electron cloud phenomena are central to the CesrTA R&D program. A small vertical emittance is required in order to be sensitive to the emittance diluting effects of the electron cloud. We have developed techniques to systematically and efficiently eliminate optical and alignment errors that are the sources of vertical emittance. Beam based...
Marco Venturini
(LBNL)
10/10/10, 3:30 PM
Poster
One of the options considered for a future aupgrade of the LHC injection
complex entails the replacement of PS with PS2, a larger
circumference and higher-energy synchrotron. Electron cloud has been identified
as a potential limitation to the machine performance. We review
studies of e-cloud build-up and present recent results of simulations of short-term
e-cloud effects on the...
Jim Crittenden
(Cornell University)
10/10/10, 3:30 PM
Poster
The Cornell Electron Storage Ring Test Accelerator (CesrTA) program includes
investigations into electron cloud buildup, applying various mitigation
techniques in custom vacuum chambers.
Among these are two 1.1-m-long sections located
symmetrically in the east and west arc regions. These chambers
are equipped with pickup detectors shielded against
the direct beam-induced signal. They...
Dr
Yulin Li
(CLASSE, Cornell University)
10/10/10, 3:30 PM
Poster
The vacuum system of Cornell Electron Storage Ring (CESR) was successfully reconfigured to support CesrTA physics programs, including electron cloud (EC) build-up and suppression studies. One of key features of the reconfigured CESR vacuum system is the flexibility for exchange of various vacuum chambers with minimized impact to the accelerator operations. This is achieved by creation of...
Mr
Jin-Sung Kim
(Cornell University)
10/10/10, 3:30 PM
Poster
Measuring secondary electron yields (SEYs) on technical surfaces in accelerator vacuum systems provides essential information for many accelerator R&D projects, such as the ILC Damping Rings, regarding to electron cloud growth and suppression. As a part of CesrTA research program, we developed and deployed SEY in-situ measurement systems. Two such SEY systems were installed to expose samples...
Joseph Calvey
(LEPP, Cornell University)
10/10/10, 3:30 PM
Poster
A great deal of Retarding Field Analyzer (RFA) data has been taken as part of the CesrTA program at Cornell. Obtaining a quantitative understanding of this data requires use of cloud simulation programs, as well as a detailed model of the RFA itself. In some cases the RFA can be modeled by postprocessing the output of a simulation codes, and one can obtain “best fit” values for important...
Kiran Sonnad
(Cornell University)
10/10/10, 3:30 PM
Poster
In this presentation, we will report the progress made in the past few years
on simulations to study the electron cloud effects on the dynamics of beams
in cicular accelerators. Results associated with various acclerators such as
the Fermilab Main Injector, SPS, LHC, ILC damping rings will be shown.
Comparisions between the results obtained from three codes, namely Warp, HeadTail
and...
Kiran Sonnad
(Cornell University)
10/10/10, 3:30 PM
Poster
The simulation code VORPAL has been used as a tool to study charecteristics of
TE wave transmission in the presence of electron clouds for CesrTA. We look at
how the electron cloud induced phase shift is influenced by (1) reflections of the
wave, caused by possible protrusions in the beam pipe and (2)effect of nonuniformities
of the cloud density distribution in the transverse plane. ...
Gerry Dugan
(Cornell University)
10/10/10, 3:30 PM
Poster
As part of the Bmad software library, a program called Synrad3d has been written to track synchrotron radiation photons generated in storage rings. The purpose of the program is primarily to estimate the intensity and distribution of photon absorption sites, which are critical inputs to codes which model the growth of electron clouds. Synrad3d includes scattering from the vacuum chamber walls...
Mr
John Sikora Sikora
(CLASSE, Ithaca, NY)
10/10/10, 3:30 PM
Poster
TE Wave measurement systems have been installed in the L0 and L3 regions of CesrTA. L0 is the location of 6 superconducting wiggler magnets; L3 has round beampipe through a chicane magnet (PEPII) and a NEG coated chamber. At both locations, rf relays are used to multiplex signals from a signal generator output, through the beampipe, and to the input of a spectrum analyzer. Software monitors...
Dr
David Kreinick
(Cornell University)
10/10/10, 3:30 PM
Poster
One technique used at CesrTA for studying the effects of electron clouds
on beam dynamics is to measure electron and positron bunch tunes under
a wide variety of beam energies, bunch charge, and bunch train
configurations. Comparing the observed tunes with the predictions of
various simulation programs allows the evaluation of important
parameters in the cloud formation models. These...
Katherine Harkay
(Argonne National Laboratory)
10/11/10, 9:00 AM
Oral Sessions
The APS Upgrade calls for the development and commissioning of a superconducting undulator (SCU) at the Advanced Photon Source (APS), a 7-GeV electron synchrotron. Operation of an SCU at ANKA, also an electron ring, suggests that electron multipacting may in part be responsible for the observed heat load and pressure rise, but this effect is not predicted by an electron cloud generation code....
Ms
Laura Boon
(Purdue University)
10/11/10, 9:30 AM
Oral Sessions
Electron cloud data from electron rings suggest that the photoelectron model in electron cloud generation codes is incomplete. The photoelectron model will be important in modeling the cloud generation on components downstream of wigglers, which can produce a very high photon flux on the wall in a local region. The code SYNRAD3D has been developed in the context of the Bmad accelerator physics...
Ms
Christine Celata
(LBNL / Cornell University)
10/11/10, 10:00 AM
Oral Sessions
Simulations of electron cloud buildup in the CESR-TA wigglers have been performed using the 3D code WARP-POSINST. The beam field is modeled using the Bassetti-Erskine electric field and does not evolve in time. The electron cloud distribution during the passage of a 45-bunch train has been examined with particular attention to the difference in dynamics at the z locations of the maximum and...
Dr
Theo Demma
(INFN)
10/11/10, 11:00 AM
Paul L. G. Lebrun
(Fermilab)
10/11/10, 11:30 AM
Oral Sessions
We present results from a precision simulation of the electron cloud (EC) problem in the Fermilab Main Injector using the code VORPAL. Fully3d and self consistent that include both distributions of electrons in6D phase-space and E.M. field maps. Various configurations of themagnetic fields found around the machine have been studied. Plasma waves associated to the fluctuation density of the...
Dr
Seth Veitzer
(Tech-X Corporation)
10/11/10, 12:00 PM
Oral Sessions
We present an overview of recent electron cloud modeling results using the multi-dimensional, parallel, plasma simulation code VORPAL. We have used VORPAL to model cloud buildup in dipole, quadrupole, and field-free magnetic field configurations, in both circular and elliptical cross section pipes relevant to microwave diagnostics at the PEP-II experiment at SLAC, and ongoing experiments in...
Lanfa Wang
(SLAC)
10/11/10, 12:30 PM
Oral Sessions
This talk will discuss the electron trapping mechanism in quadrupole and sextupole magnets. We will present the results in CESRTA and ILC quadrupole and sextupole magnets.
Dr
jayakar thangaraj
(Fermilab)
10/11/10, 2:30 PM
Oral Sessions
In this paper, we present recent results from our measurement at the Fermilab Main Injector through microwave transmission in a beam pipe. We present three types of measurement techniques. In the first technique, we use time-resolved direct phase shift measurement to measure the e-cloud density. In the second and third techniques, we look for side bands in the frequency spectrum with or...
Dr
Stefano De Santis
(LBNL)
10/11/10, 3:00 PM
Oral Sessions
TE wave transmission is currently used as a diagnostic tool for measurements of the electron cloud density in several regions of the Cesr-TA ring.
While the method is conceptually well established, a number of effects contribute to making a quantitative estimate of the density not straightforward.
We report on the measurements currently performed during Cesr-TA experimental runs, describe...
Dr
Cheng-Yang Tan
(Fermilab)
10/11/10, 3:30 PM
Oral Sessions
An ecloud measurement setup was installed in a straight section of the Main Injector in 2009. The goal of the setup was to compare the characteristics of different beam pipe coatings when subjected to proton beam. The setup consists of one coated and one uncoated beam pipe with the same physical dimensions installed at the same location. Four RFAs (retarding field analysers) and two BPMs (used...
Ken-ichi Kanazawa
(KEK)
10/11/10, 4:30 PM
Oral Sessions
In a positron ring such as KEKB LER, clouding electrons receive an almost instantaneous kick from circulating bunches. Therefore, high energy electrons in the cloud are produced just after the interaction with the bunch locally around the beam. The authors gave an estimation of their density using a high energy electron current measured with RFA and a calculated volume neglecting their initial...
Mr
Stefan Gerstl
(Karlsruhe Institute of Technology (KIT))
10/11/10, 5:00 PM
Oral Sessions
One of the still open issues for the development of superconducting insertion devices is the understanding of the heat load induced by the beam passage. With the aim of measuring the beam heat load to a cold bore and in order to gain a deeper understanding in the beam heat load mechanisms, a cold vacuum chamber for diagnostics is under construction. We plan to have access with the same set-up...
Dr
Robert Macek
(LANL and TechSource, Inc.)
10/11/10, 5:30 PM
Oral Sessions
Since the ECLOUD’07 workshop, our electron cloud studies have focused on understanding the main sources and locations of electron clouds (EC), which drive the observed e-p instability. Significant EC signals are observed in drift spaces and quadrupole magnets at PSR which together cover ~65% of the ring circumference. Measurements using the EC diagnostic in a quadrupole have also shown...
Mr
Miguel Furman
(LBNL and Cornell Univ.)
10/12/10, 9:00 AM
Oral Sessions
We review the simulation results for the electron cloud build-up for the ILC Damping Rings, for both lattice options considered (6 km and 3 km), in a field-free region and in a bending dipole magnet. While the 6 km lattice is slightly more forgiving than the 3-km lattice vis-a-vis the electron cloud effects, we conclude that, in general, the existence of an antechamber helps to dramatically...
Dr
Mark Palmer
(Cornell University)
10/12/10, 9:30 AM
Oral Sessions
The first phase of the CesrTA experimental program is now complete. Electron cloud research over the course of the last 2.5 years has focused on two principle topics. The first is the characterization of methods to mitigate the electron cloud build-up in each of the magnetic field regions of concern for damping ring design. The second is the characterization of the cloud's impact on...
Dr
Mauro Pivi
(SLAC)
10/12/10, 10:30 AM
Oral Sessions
As part of the international Linear Collider (ILC) collaboration, we have compared the electron cloud (EC) effect for different Damping Ring (DR) designs respectively with 6.4 km and 3.2 km circumference and investigated the feasibility of the shorter damping ring with respect to the electron cloud build-up and related beam instabilities. The studies for a 3.2 km ring were carried out with...
Dr
Suetsugu Yusuke
(KEK)
10/12/10, 11:00 AM
Oral Sessions
The upgrade of KEKB to Super KEKB has just started. Now the design work of the positron ring is underway. The present mitigation plan of the electron cloud effect will be reported.
Prof.
Don Hartill, Dr
Yusuke Suetsugu
(KEK)
10/12/10, 1:30 PM
Kiran Sonnad
(Cornell University), Dr
Robert Zwaska
(Fermilab)
10/12/10, 1:45 PM
Mr
David Rubin
(Cornell University),
Mauro Pivi
(SLAC National Accelerator Laboratory)
10/12/10, 2:00 PM
Gerry Dugan
(Cornell University), Mr
Roberto Cimino
(Istituto Nazionale di Fisica Nucleare (INFN/LNF) Laboratori Nazionali di Frascati)
10/12/10, 2:15 PM
Dr
John Flanagan
(KEK), Mr
Michael Billing
(CLASSE)
10/12/10, 2:30 PM
Dr
James Crittenden
(Cornell University), Dr
Marc Ross
(FNAL)
10/12/10, 2:45 PM
Mr
Miguel Furman
(LBNL and Cornell Univ.)
Oral Sessions
We will provide an introductory overview of the ingredients that make up the physical model used for the simulation of the electron-cloud build-up and decay in the presence of a given, prescribed, beam. The three primary electron generation mechanisms (photoemission, ionization of residual gas, and electron generation from beam stray particles striking the chamber walls) will be presented,...
