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

目的：高质量、强流亚毫米波光束的产生及其在等离子体散射测量中的应用，目的是提高测量性能（信噪比、空间分辨率和波数分辨率）。亚毫米波强流源高频回旋管的研制设计并制造了一台17 T超导磁体的亚毫米波高频回旋管。实验结果表明，从158至443 GHz的基波和从336至838 GHz的二次谐波的操作。亚毫米波回旋管通过调整工作参数，也能在长脉冲（P=110 W，功率起伏<8%，f=354 GHz，τ = 0.6s）下获得稳定的输出.一种用于高质量束流产生的准光传输线的研制设计了一种用于将回旋管输出转换为高质量束流的新型传输线。这包括一个准光学天线，镜子和偏振器。使用惠更斯方程的分析支持该系统可以产生高质量的光束。该系统的旁瓣不超过-30 dB，镜像源的大部分功率（83%）都传输到波束中心.用亚毫米波回旋管作电源的等离子体散射测量为了观测紧凑螺旋系统（CompactHelicalSystem，CHS）等离子体中的低频密度起伏，在ICRF加热等离子体中，用亚毫米波回旋管作电源进行了等离子体散射测量。结果与频率为39 GHz的反射率测量结果一致。最终的目标是应用一个高品质，高强度的光束在亚毫米波范围内的散射测量，目的是提高测量的性能（S/N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).