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The inverse Smith-Purcell effect in the subillimeter region

亚毫米区域的逆史密斯-珀塞尔效应

基本信息

批准号：
61460140
负责人：
MIZUNO Koji
金额：
$ 4.48万
依托单位：
TOHOKU UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1986
资助国家：
日本
起止时间：
1986 至 1987
项目状态：
已结题

项目摘要

The inverse Smith-Purcell (ISP) effect is one of the candidates for laser-driven linacs with a metallic grating as an interaction circuit to produce acceleration gradient of a few GeV/m. The purposes of the project are to demonstrate experimentally the ISP effect by using a submillimeter wave (SMM) laser and confirm validity of theoretical predictions on the effect.We performed the theoretical analyses of the ISP effect in the SMM region in order to design the experimental equipents necessary to demonstrate it. The optimum groove dimensions of the grating with rectangular profile were determined for various SMM laser lines by analyzing the electric field distribution just in front of the grating surface. Also with computer simulations, it has been found that a laser power of lW can produce [[30eV increase in the electron energy spectrum.We have constructed the experimental system based upon the theoretically analyzed results. The system consists of an optically pumped SMM laser and the electron beam system which includes the metallic grating fabricated on a milling machine according to the theoretical design. The SMM CH_3F molecular laser with the wavelength of 496<mu>m was pumped by an EQ- switched CO_2 laser newly developed for this project. The CH_3F laser had the maximum peak power of 46W, the repetition rate of up to 9.2kHz, and regular output pulse shape under the fundamental transverse mode of operation.In early 1987, we have successfully observed the ISP effect for the first time. The experimental results showed that lW laser power produces an increase of approximately 18eV in the full width for the energy spectrum of electrons. Furthermore. we measured electron energy change as a function of the laser power and of the initial electron energy. These experimental results gave good agreement with the theoretical perdictions.

逆Smith-Purcell（ISP）效应是激光直线加速器的候选效应之一，它以金属光栅作为相互作用电路，产生几GeV/m的加速梯度。本计画的目的是利用次毫米波（SMM）来实验验证ISP效应为了设计实验装置，我们对SMM区的ISP效应进行了理论分析。通过分析确定了不同SMM激光线的矩形光栅的最佳槽形尺寸，并对实验结果进行了分析。结果表明，在不同的SMM激光线上，矩形光栅的槽形尺寸是最佳的光栅表面正前方的电场分布。通过计算机模拟，发现1 W的激光功率可以使电子能谱增加[30 eV]，并根据理论分析结果建立了实验系统。该系统由光泵SMM激光器和电子束系统组成，电子束系统包括根据理论设计在铣床上加工的金属光栅。采用<mu>本课题新研制的EQ开关CO_2激光器作为抽运源，实现了波长为496 m的单模CH_3F分子激光器。CH_3F激光器的最大峰值功率为46 W，重复频率高达9.2kHz，在基横模工作下，输出脉冲形状规则，1987年初，我们首次成功地观察到ISP效应。实验结果表明，1 W激光功率使电子能谱全宽增加约18 eV。此外。我们测量了作为激光功率和初始电子能量的函数的电子能量变化。实验结果与理论预测吻合较好。