The Inverse Smith-Purcell Effect at Submillimeter Wavelengths

本研究计划从实验和理论两方面研究逆Smith-Purcell （ISP）效应，以证实在激光驱动直线加速器中电子加速到数GeV/m的可能性。为了证明输出功率大于几TW的co2激光器在红外波段的ISP效应，对亚毫米波波段的ISP效应的实验结果进行了理论上的详细讨论。在与红外激光相互作用的ISP效应实验中，可以得到每秒1000个电子的输出信号。这表明在10.6 μ m的红外波段观测到这种效应是可能的。在此基础上，设计并制作了一套实验装置。研制了emq开关CO_2激光器作为驱动激光器，用于ISP效应实验。该激光器是一种新型调q脉冲激光器，其输出功率为7OkW，重复频率高达9.2kpps，工作方式为基本高斯模式。利用光学透镜系统将co2激光器发出的红外光束引导到放置在高真空室中的光栅表面。利用硅的反各向异性蚀刻技术制备了硅（Si）光栅，使光栅常数的设计值误差保持在<正负>.1 μ m以内。电子测量系统每秒可检测100个粒子以下的电子。

This research project has been planned to study the inverse Smith-Purcell (ISP) effect experimentally and theoretically in order to confirm a possibility of an electron accelerating to several GeV/m by a laser-driven linacs.In order to demonstrate the ISP effect at infrared wave region in which a C0_2 laser with an output power more than several TW exists, it has been discaussed theoretically in detail for the experimental results on the effect at submillimeter wave region. It has been found that an output signal of 1000 electrons per second can be obtained in the experiment of the ISP effect which are interacted with an infrared laser light. This shows that an observation of the effect at infrared wavelength of 10.6mum is possible. Based on the discussions described above, an experimental apparatus has been designed and fabricated as follows,1. EMQ-switched CO_2 laser has been developed as a driving laser for an experiment of the ISP effect. This laser is new type Q-switched pulse laser with an output power of 7OkW and a repetition rate up to 9.2kpps for a fundamental Gaussian mode of operation.2. Optical lens system is used to guide an infrared light beam from the C0_2 laser to the grating surface placed in a high vacuum chamber.3. Silicon (Si) Gratng has been fabricated by using an antisotropic etching of Si to keep tolerances within <plus-minus>0.1mum for the designed values of the grating constan4. Electron measurement system can detect electrons below 100 particles per second.