Development of the New Double-Path Interferometer for the Measurements of Electron Density and Conductivity in the MHD Plasma

在大尺度MHD通道中，获取电子密度和电导率的涨落及其相互关系的信息将变得非常重要。远红外(FIR)激光为这一目的提供了强大的诊断工具，通过这项研究建立了能够同时测量电子密度和电导率的方法。在本研究项目中，提出了一种新的干涉仪，它可以测量电子密度和电导率的大波动，具有很高的时间和空间分辨率。该干涉仪在传统的迈克尔逊干涉仪的基础上增加了另一条干涉路径，能够测量条纹漂移超过2pi的大起伏。该系统是在煤油燃烧的实验磁流体通道上搭建和测试的。研究结果总结如下：1.研究成果。为了建立稳定的远红外干涉仪，设计并制作了新型氢化氢激光器。实验证明，该激光器工作稳定，可用于干涉仪系统。设计并制作了基于全新概念的干涉仪。这比传统的迈克尔逊干涉仪多了一条干涉仪路径。同时，利用肖特基势垒二极管进行了起伏检测。编制了考虑多路干涉光路影响的软件。结果表明，该系统能够以较高的时间和空间分辨率测量电子密度和电导率的起伏。

In a large scale MHD channel, it will become important to get information on the fluctuations of the electron density and electrical conductivity, and on the correlation between them. The far-infrared (FIR) laser has offered a powerful diagnostic tool for this purpose, and the method was establish by this research that enabled the simultaneous measurements of electron density and conductivity. In the present research project, the new interferometer is proposed that could measure the large fluctuation of the electron density and conductivity with high temporal and spacial resolution. This interferometer adds another interferometric path to the conventional Michelson interferometer, and is capable of measuring the large fluctuation with the fringe shifts over 2pi. This system was constructed and tested with the experimental MHD channel operated by the combustion of kerosene. The results are summarized as follows.1. To establish the stable FIR interferometer, the new HCN laser was designed and made. This laser was proved to operate successfully and shown to be used in the interferometer system.2. The interferometer based on the entirely new concept was designed and made. This has one more interferometer path in the conventional Michelson interferometer. Also, the Schottky-barrier-diode was used to detect the fluctuation. The software that took into account the multiple interferometer path was made. It was shown that the present new system could successfully measure the fluctuations of the electron density and conductivity with high temporal and spatial resolution.