High-quality electron beams generation in a linear upramp density target

¹ Applied Ion Beam Physics Laboratory, Key Laboratory of the Ministry of Education, Institute of Modern Physics, Fudan University - Shanghai 200433, PRC
² Institute of Physics of the ASCR, ELI-Beamlines project - Na Slovance 2, 18221 Prague, Czech Republic
³ Department of Advanced Interdisciplinary Sciences, Utsunomiya University - Yohtoh 7-1-2, Utsunomiya 321-8585, Japan

^(a) qkong@fudan.edu.cn (corresponding author)

Received: 8 December 2014
Accepted: 30 April 2015

Abstract

A key issue of laser-plasma accelerator is to improve the accelerated electrons qualities. Here, we present a regime based on controlling bubble velocity, which allows us to obtain a high-quality electron bunch having both a high energy (multi-GeV) and an ultra-low energy spread (0.3%), while retaining an ultra-low emittance and an high charge at the same time. As an electron bubble propagating in inhomogenous plasma, its velocity will change with the local plasma density. The achievement of this scheme is ascribed to the bubble velocity first above, then below the light speed by tailoring longitudinal plasma density to be a linear upramp. We also specify the range of the parameters in which the regime can be realized in a linear density upramp.