Conversion of Submillimeter Wave Gyrotrn Output into a high Quality Beam and its Application to Plasme Scattering Measurement

目的：制备高质量、强亚毫米波光束并将其应用于等离子体散射测量，以提高测量性能（信噪比、空间分辨率和波数分辨率）。采用17t超导磁体，设计并制造了亚毫米波波长范围的高频回旋管。实验结果表明，该系统在基频工作范围为158 ~ 443 GHz，次谐波工作范围为336 ~ 838 GHz。亚毫米波回旋管也可以在长脉冲（P=110 W，功率波动水平<8%,f= 354ghz, τ -0.6s）下通过密切调节工作参数产生稳定输出。高质量光束准光传输线的研制设计了一种将回旋管输出转换成高质量光束的新型传输线。它由准光学天线、反射镜和偏振器组成。利用惠更斯方程分析表明，该系统可以产生高质量的光束。没有超过30db的旁瓣。像源的大部分功率（83%）被转移到光束中心。利用亚毫米波回旋管作为电源的等离子体散射测量为了观测CHS（紧凑螺旋系统）等离子体中的低频密度波动，在ICRF加热等离子体中使用亚毫米波回旋管作为电源进行了等离子体散射测量。结果与频率为39ghz的反射测量结果一致。最终目标是在亚毫米波范围内应用高质量，高强度的光束进行散射测量，以提高测量性能（信噪比，空间和波数分辨率）。

Objectives : Production of high quality, intense submillimeter wave beam and its application to plasma scattering measurement with the aim of improving performance of the measurement (S/N ratio, spatial and wave number resolutions)The results :1. Development of a high frequency gyrotron as intense power source in submillimeter wave rangeA high frequency gyrotron in the submillimeter wavelength range using 17 T superconducting magnet has been designed and constructed. Experimental results have demonstrated operation from 158 to 443 GHz at the fundamental and from 336 to 838 GHz at the second harmonic. A submillimeter wave gyrotron can also produce steady outputs in a long pulse (P=110 W,power fluctuation level<8%, f=354 GHz, tau-0.6s) by closely adjusting the operation parameters.2. Development of quasi-optical transmission line for producing a high quality beamA new transmission line is designed for converting gyrotron output into a high quality beam. This consists of a quasi-optical antenna, mirrors and polarizer. Analysis using the Huygens equation supports that this system can produce a high quality beam. There is no sidelobe of more than-30 dB.Most of the power (83%) of the image source is transferred to beam center.3. Plasma scattering measurement using a submillimeter wave gyotron as a power sourceIn order to obseve low frequency density fluctuations in the CHS (Compact Helical System) plasma, a plasma scattering measurement using a submillimeter wave gyrotron as a power source is carried out in ICRF heated plasmas. The results correspond to those of reflectmetry with frequency of 39 GHz. The final goal is to apply a high quality, high intensity beam in the submillimeter wave range to scattering measurements with the aim of improving performance of the measurement (S/N ratio, spatial and wave number resolutions).