The application of stable, high power, twin frequency, optically pumped far-infrared lasers to fusion plasma diagnostics

Summary form only given, as follows. There is presently considerable worldwide interest in the study of high temperature plasmas. Much of this interest is driven by the goal of achieving controlled thermonuclear fusion, which involves the release of net nuclear energy from the fusion of light nuclei such as deuteneum and mtuim. In order to understand many of the issues and problems relating to the physics of magnetically confined plasmas, there is a need for accurate, high resolution and flexible diagnostic systems. The far-infrared spectral region (100-1OOO pm) is ideally suited to a number of fusion plasma diagnostic techniques such as collective Thomson scattering, multichannel interferometry and polarimetry. The only practical radiation source currently available is *e optically pumped far-infrared (FIR) laser. This paper describes the development of a high power, stable, twin frequency FIR laser for diagnosis of fusion plasmas. The use of buffer gases, temperature optimization and operation of the laser in both ring and linear cavities will be described. In addition, diagnostic measurements on the TEXT device will be presented to demonsuate the flexibility and importance of FIR diagnostics in the fusion program.