Verification of Multistage Particle Acceleration by Laser Beat-waves

本项目的目的是验证利用超短脉冲激光对被激光拍波加速后的MeV电子进行后级加速的可行性。因此，在过去的两年里，我们主要建立了一个超短脉冲高强度激光系统。在第一年(1995年)，我们展示了伴随着CO_2激光的几百keV的电子加速和背向拉曼散射。因此，加速的高能电子是注入激光加速器的种子电子，可以是拍波电子，也可以是尾波电子。利用激光汤姆逊散射测量了拍波激励相对论等离子体波的时间分辨谱和空间分辨谱。我们已经开始建造用于电子后加速的短脉冲玻璃激光系统，并在第二年(1996年)将Gekko Mii玻璃激光系统改装为短脉冲激光系统。我们将前端改为钛宝石振荡器和再生放大器组合系统。在最终的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的功率下产生25J的能量。现在我们正在进行固体靶照明，在那里可以探测到高能离子和中子。不久，我们将进行气体喷射实验，在这个实验中，尾波场将被激发，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.