Abstract: A CO₂ laser coherent scattering diagnostic system was successfully developed on the HL-2A tokamak. The tangential optical path layout which can improve the spatial resolution of the system and a dual-channel homodyne detection design were adopted. The two channels can simultaneously measure the small-scale turbulent changes of the plasma core (ρ≈0.28) with wavenumber in the range of 10~45cm⁻¹. The wave number resolution is ±3cm⁻¹ and the time resolution is 0.5μs. The system can provide important data for the study of plasma core transport. In addition, the main beam and the local oscillator beam of the diagnostic system pass through the plasma at the same time, which can also detect various large-scale plasma fluctuations in the core. The analysis of the diagnostic signals indicates that the system can accurately respond to the evolution of the small-scale turbulence in the plasma core, and also provide useful information for studying the macro-instability in the core area of plasma.

Key words: Laser collective scattering, Density fluctuation, Short-scale turbulence

摘要： 在HL-2A装置上成功研制了一套CO₂激光相干散射诊断系统，采用了能提高系统空间分辨的切向布局以及双通道的零差式探测设计。两个通道能够同时测量等离子体芯部(ρ≈0.28)波数在10~45cm⁻¹范围中小尺度的湍流变化，其波数分辨率为±3cm⁻¹，时间分辨率为0.5 QUOTE  μs，能够为等离子体芯部输运研究提供重要数据。此外，由于本诊断系统采用的是主光束与本振光束同时穿过等离子体的光路设计，它还能够探测到等离子体芯部的大尺度宏观等离子体扰动。诊断信号的分析结果显示该系统可以准确地响应等离子体芯部小尺度湍流的变化，同时也能够为芯部宏观不稳定研究提供诊断数据。

关键词: 激光相干散射, 密度扰动, 小尺度湍流