Budker Institute of Nuclear Physics, 630090 Novosibirsk, Russia.
Novosibirsk State University, 630090 Novosibirsk, Russia.
Rev Sci Instrum. 2023 Mar 1;94(3):033509. doi: 10.1063/5.0123329.
The incoherent Thomson scattering diagnostic with multiple lines of sight is installed at the gas dynamic trap (GDT) for measurements of radial profiles of the plasma electron temperature and density. The diagnostic is built on the Nd:YAG laser operating at 1064 nm. The laser input beamline is provided with an automatic system for alignment status monitoring and correction. The collecting lens uses ∼90° scattering geometry having 11 lines of sight in total. Presently, six of them (covering the full plasma radius from the axis to the limiter) are equipped with high etendue (f/2.4) interference filter spectrometers. The design of the spectrometer's data acquisition system based on the "time stretch" principle allowed for the 12 bits vertical resolution with a sampling rate of 5 GSample/s and a maximum sustainable measurement repetition frequency of 40 kHz. The repetition frequency is the crucial parameter for the study of plasma dynamics with a new pulse burst laser to be started in early 2023. Results of the diagnostic operation in several GDT campaigns show that radial profiles are routinely delivered with the typical observation error of 2%-3% for T ⩾ 20 eV in a single pulse. After Raman scattering calibration, the diagnostic is capable to measure the electron density profile with the resolution n ≃4⋅10m and error bars of 5%.
多视线非相干汤姆逊散射诊断仪安装在气体动力学阱（GDT）上，用于测量等离子体电子温度和密度的径向分布。该诊断仪建在 Nd：YAG 激光上，工作波长为 1064nm。激光输入光路配备了自动对准状态监测和校正系统。收集透镜采用约 90°散射几何结构，总共有 11 条视线。目前，其中 6 条（覆盖从轴到限制器的整个等离子体半径）配备了具有高孔径（f/2.4）的干涉滤光片光谱仪。基于“时间拉伸”原理设计的光谱仪数据采集系统允许 12 位垂直分辨率、5GSample/s 的采样率和最大可持续测量重复频率为 40kHz。重复频率是研究 2023 年初即将启动的新脉冲激光束等离子体动力学的关键参数。在几次 GDT 运行中的诊断运行结果表明，在单个脉冲中，对于 T ⩾ 20eV，通常可以以 2%-3%的典型观测误差提供径向分布。经过喇曼散射校准后，该诊断仪能够以 n ≃4⋅10m 的分辨率和 5%的误差条测量电子密度分布。
