Verification of Multistage Particle Acceleration by Laser Beat-waves

本计画的目的是验证利用超短脉冲激光对MeV电子进行多级激光加速的可行性，即利用激光拍频波对MeV电子进行后加速。因此，在过去的两年中，我们主要建立了一个超短脉冲高强度激光系统，第一年（1995年），我们演示了几百keV的电子加速和CO_2激光后向拉曼散射。因此，被加速的高能电子是将被注入到激光加速器中的种子电子，无论是拍频波还是韦克菲尔德激光加速器。利用YAG激光汤姆逊散射，测量了拍波激发的相对论等离子体波的时间和空间分辨谱。我们已经开始建立一个短脉冲玻璃激光系统，用于电子的后加速，第二年（1996年），我们将Gekko MII玻璃激光系统改造成短脉冲激光。我们已经改变了前端钛：蓝宝石振荡器和再生放大器组合系统。在最后一个空间滤波器的输出端，我们放置了一个脉冲压缩光栅对。完成的系统在0.7ps或35TW产生了25J的能量。现在我们正在进行固体靶照射，在那里探测高能离子和中子。不久我们将做气体喷射实验，在这个实验中，韦克菲尔德将被激发，电子将被加速。

The purpose of this project is to verify multistage laser acceleration feasibility using an ultra short pulse laser, which is to after-accelerate MeV electrons once accelerated by the laser-beat-wave. Soin the past two years, we have mainly constructed an ultra-short pulse high intensity laser system.In the first year (1995), we have demonstrated electron accelerations of a few hundred keV accompanied with a CO_2 laser backward Raman scattering. Thus accelerated high energy electrons are the seed electrons to be injected into the laser accelerator, either beat-wave or wakefield one. By YAG laser Thomson scattering, we have measured both temporally and spatially resolved spectrum of beat-wave excited relativistic plasma waves. We have started to construct a short pulse glass laser system for after-acceleration of electrons.In the second year (1996), we have modified the Gekko MII glass laser system to short pulse laser. We have changed the front end to Ti : Sapphire oscillator and regenerative amplifier combination system. At the output of the final spatial filter we put a pulse compression grating pair. The completed system produces 25J in 0.7ps or 35TW.Now we are doing a solid target illumination, where high enegy ion and neutron are detected. Soon we will do gas-jet experiment, in which the wakefield will be excited and electrons will be accelerated.