Speaker
Description
Generation of high-quality electron beams in plasma-based acceleration is a critical and active topic in the past decade. By conducting full-scale particle-in-cell simulations, we have shown that electron beams with ultra-high brightness (10^20 ~10^21 A/m^2/rad^2) and 0.1~1 MeV energy spread can be produced in density downramp injection in the three-dimensional blowout regime of plasma-based acceleration. Two underlying physical mechanisms that lead to the generation of high-quality electrons are uncovered: transverse deceleration and longitudinal mapping. Recently, we pointed out the injection in a slowly expanding bubble caused by the evolution of a laser pulse driver or an electron beam driver in a uniform plasma shares the same dynamics as downramp injection, thus can indeed produce high quality self-injected electron beams. Furthermore, we proposed to generate a high-quality electron beam with nanometer-scale current modulation in a density modulated downramp. These high-quality beams have many potential applications in X-ray free-electron lasers, such as drive a fully coherent XFEL in a short undulator.