Development of Plasma Diagnostics for the FIRST - III

Yen-Lin Chen⁴, Wei Huang⁴, Yolanda (Yu-Wei) Su¹, Ting-Yuan Li¹, Yu-Wei Ko¹, Wen-Yu Yang¹, Robert (Shu-I) Hu¹, Tzu-Hsiang Lin², Ming-Wei Lin^2*, Chia-Hao Chang³, Keh-Chyang Leou⁴

¹Department of Electrical Engineering, National Yang Ming Chiao Tung University, Hsinchu, Taiwan
²Institute of Nuclear Engineering and Science, National Tsing Hua University, Hsinchu, Taiwan
³Mechnical and System Research Laboratories, Industrial Technology Research Institute, Hsinchu, Taiwan
⁴Department of Engineering and System Science, National Tsing Hua University, Hsinchu, Taiwan

* Presenter:Ming-Wei Lin, email:mwlin@mx.nthu.edu.tw

Here we will give an overview of the third part of the development of plasma diagnstics for the FIRST, with collaborations and integrated efforts from three institutes, i.e., NTHU, NYCU, and ITRI. The diagnostic menthods cover a wide range of techniques, ranging from electrostatic, microwaves, to radiations, including visible to soft X-ray wavelengths. A three electrode Langmuir probe, or triple probe, has been developed for measurements of basic plasma parameters, such as plasma density and electron temperature, near plasma edge region in the FIRST. The triple probe system will be also integrated into the EBE (electron Bersnstein imaging) system for measurement of plasma density gradient. We have also developed a basic Ka-band reflectometer for measurement of plasma density fluctuations during plasma heating or current drive. This reflectometer is also being upgrated to a FMCW and an AM reflectormeter for measurement of plasma density gradient or profile in the FIRST. In addition, collaboration with the MMWPDG (Millimeter Wave Plasma Diagnostics Group) of UC-Davis has been established recently for the develpment of rf-IC based modules for advanced millimeter wave diagnostics system for ITER/DEMO, as well as milliter-wave optics for the FIRST. The optical image of plasma discharges in the FIRST will be acquired by a high speed camera installed on a view port on the FIRST chamber to record spatial temporal profile of discharge optical emissions. The transient behavior of Hα and Hβ emissions from the hydrogen plasma discharges in the FIRST will be obtained by using two modules consisting of bandpass filters and high speed detctors. Furthermore, a soft X-ray diagnostic system—comprising a silicon drift detector (SDD) and Absolute eXtreme Ultra-Violet (AXUV) photodiodes—will be developed to measure electron temperature and impurity composition in hot plasma. These plasma diagnostics tools have been either tested or calibrated by using existing plasma or radiation sources, or home-made test bench. A brief introduction of the principles of these diagnostics methodes and their initial test/calibration results will be presented, along with the integration of a digitizer to organize signals from all X-ray detectors .

Keywords: plasma diagnostics, Langmuir probe, millimeter wave reflectometer, soft X-ray diagnostics