Schroeder C B, Lee P B, Wurtele J S, Esarey E, Leemans W P
Department of Physics, University of California at Berkeley, Berkeley, California 94720, USA.
Phys Rev E Stat Phys Plasmas Fluids Relat Interdiscip Topics. 1999 May;59(5 Pt B):6037-47. doi: 10.1103/physreve.59.6037.
A proposed laser-plasma-based relativistic electron source [E. Esarey et al., Phys. Rev. Lett. 79, 2682 (1997)] using laser-triggered injection of electrons is investigated. The source generates ultrashort electron bunches by dephasing and trapping background plasma electrons undergoing fluid oscillations in an excited plasma wake. The plasma electrons are dephased by colliding two counterpropagating laser pulses which generate a slow phase velocity beat wave. Laser pulse intensity thresholds for trapping and the optimal wake phase for injection are calculated. Numerical simulations of test particles, with prescribed plasma and laser fields, are used to verify analytic predictions and to study the longitudinal and transverse dynamics of the trapped plasma electrons. Simulations indicate that the colliding laser pulse injection scheme has the capability to produce relativistic femtosecond electron bunches with fractional energy spread of order a few percent and normalized transverse emittance less than 1 mm mrad using 1 TW injection laser pulses.
对一种基于激光等离子体的相对论电子源[E. 埃萨雷等人，《物理评论快报》79, 2682 (1997)]进行了研究，该源采用激光触发电子注入。该源通过使在激发的等离子体尾波中经历流体振荡的背景等离子体电子发生相位失配并俘获它们，来产生超短电子束团。通过使两个反向传播的激光脉冲碰撞，产生一个慢相速度拍频波，从而使等离子体电子发生相位失配。计算了俘获的激光脉冲强度阈值以及注入的最佳尾波相位。利用规定的等离子体和激光场对测试粒子进行数值模拟，以验证解析预测，并研究被俘获的等离子体电子的纵向和横向动力学。模拟表明，使用1太瓦的注入激光脉冲，碰撞激光脉冲注入方案有能力产生分数能量展宽为百分之几量级且归一化横向发射度小于1毫米毫弧度的相对论飞秒电子束团。
