Plasma Diagnostics Using Millimeter-and Submillimeter-Wave Two-Dimensional Imaging Array

1)在本课题的研究过程中，研制了频率为70 GHz的新型相位成像干涉仪。该系统由以下部分组成：i)新研制的二维探测器阵列。该探测器具有4x4个通道，由束引线GaAs肖特基势垒二极管粘结到在熔融石英衬底上单片制作的蝶形天线上。ii)干涉仪由一个准光传输系统和一个外差接收器组成，外差接收器有两个独立的振荡器。振荡器之间的拍频通过使用锁相环电路来稳定。一个双下变频系统(频率跟踪接收器)使我们能够使用中心频率为455kHz的鉴相器。2)相位成像干涉仪已经连接到Gamma 10串行镜的插头单元。干涉仪的空间分辨率由天线阵的口径和光学系统的放大倍数决定。垂直分辨率是在…估计的平均直径2.7 cm，水平直径2.5 cm，用介电靶定标。位相分辨率小于1/200条纹，相当于2.5×10~(-1)cm~(-2)的线密度。3)该成像系统还作为外差接收器应用于电子回旋加速器发射的测量。从光学细小的常模和非常模发射信号的比值，我们确定了塞室等离子体热电子温度的径向和轴向分布。通过对两个电磁场信号的相关性研究，研究了温度波动的原因。4)对该探测器进行了90 GHz高频段的测试。其灵敏度与70 GHz频率下的灵敏度相近。研究了以天线和砷化镓肖特基二极管为衬底的单片成像阵列在毫米波到亚毫米波的应用。较少

1)During the period of this research project, a new phase imaging interferometer with frequency of 70 GHz has been developed. The system consists of the following components.i)Two-dimensional detector array was newly developed. The detector has 4x4 channels consisting of beam-lead GaAs Schottky barrier diodes bonded to bow-tie antennas monolithically fabricated on a fused-quartz substrate.ii)The interferometer consists of a quasi-optical transmission system and a heterodyne receiver with two separate oscillators. The beat frequency between the oscillators is stabilized by using a phase-lock-loop circuit. A double down-converted system(frequency tracking receiver)enabled us to use phase detectors with center frequency of 455kHz.2)The phase imaging interferometer has been to the plug cell of the GAMMA 10 tandem mirror. The spatial resolution of the interferometer is given by the aperture of the antenna array and the magnification of the optical system. The vertical resolution was estimat … More ed to be 2.7cm and horizontal one was 2.5cm, which were calibrated with a dielectric target. The phase resolution was less than 1/200 fringe, which equals to the line density of 2.5x10^<11>cm^<-2>. The system was successfully applied to the measurement of the line density profile during the operation of plug-potential formation.3)The imaging system has also been applied to the measurement of electron cyslotron emission(ECE)as a heterodyne receiver. From the ratio of the optically thin ordinary and extraordinary mode emission signals, we have determined the radial as well as axial profile of the warm and hot electron temperature of the plug-cell plasma. The temperature fluctuation were investigated from correlation study of two ECE signals. This was the first application to ECE imaging measurement.4)The detector was tested at the higher frequency of 90 GHz region. The sensitivity was similar to that at the frequency of 70 GHz. The monolithic imaging array with antennas and GaAs Schottky diodes completed on a substrate has been investigated for the application to millimeter to submillimeter wave. Less