Li Y G, Zhou Y, Li Y, Deng Z C, Wang H X, Yi J
Southwestern Institute of Physics, P.O. Box 432, Chengdu 610041, China.
Rev Sci Instrum. 2017 Aug;88(8):083508. doi: 10.1063/1.4997070.
A new four-chord Michelson-type formic acid (HCOOH, λ = 432.5 μm) laser interferometer has been successfully commissioned on the HL-2A tokamak to measure the electron density and density fluctuations. Due to the employment of the two-laser heterodyne technique, the time resolution of the interferometer reached 1.0 microseconds (μs). Four chords of line electron densities with a line-averaged density resolution 2 × 10/m were obtained in a recent HL-2A experimental campaign, and detailed electron density fluctuations, caused by events such as edge localized mode, sawtooth precursor-oscillations, and energetic particle driven instabilities, were distinctly measured. In particular, the high-frequency electron density fluctuations (up to 500 kHz) caused by the reversed shear Alfvénic eigenmode were observed by the internal two interferometry channels, and their fluctuation location could be approximately identified from the spectra characteristics of multi-chord line electron densities.
一种新型的四弦迈克尔逊型甲酸（HCOOH，λ = 432.5μm）激光干涉仪已成功在HL-2A托卡马克装置上投入使用，用于测量电子密度和密度涨落。由于采用了双激光外差技术，干涉仪的时间分辨率达到了1.0微秒（μs）。在最近的一次HL-2A实验中，获得了四条线平均密度分辨率为2×10/m的线电子密度弦，并且清晰地测量到了由诸如边缘局域模、锯齿前驱振荡和高能粒子驱动的不稳定性等事件引起的详细电子密度涨落。特别是，通过内部的两个干涉测量通道观测到了由反向剪切阿尔文本征模引起的高频电子密度涨落（高达500kHz），并且可以从多弦线电子密度的光谱特征大致确定其涨落位置。
