At anticipated high electron temperatures in ITER, the effects of electron thermal motion on phase measurements made by the toroidal interferometer/polarimeter (TIP) and poloidal polarimeter (PoPola) diagnostics will be significant and must be precisely treated or the measurement accuracy will fail to meet the specified requirements for ITER operation. We calculate electron thermal corrections to the interferometric phase and polarization state of an electromagnetic wave propagating along tangential and poloidal chords (Faraday and Cotton–Mouton polarimetry) and incorporate them into the Stokes vector equation for evolution of polarization. Although these corrections are small at electron temperatures Te ≃ 1 keV, they become sizable at Te ⩾ 10 keV. The precision of the previous lowest order linear in the τ = Te/mec2 model may be insufficient; we present a more precise model with τ2-order corrections to satisfy the high accuracy required for ITER TIP and PoPola diagnostics. Proper treatment of temperature effects will ensure more accurate interpretation of interferometric and polarimetric measurements in fusion devices like ITER and DEMO. The use of precise analytic expressions is especially important for burning plasmas where various interferometric techniques will be used for direct real time feedback control of device operations with time resolution ∼1 ms to regulate the rate of the thermonuclear burn and monitor/control the safety factor profile.
在ITER中预期的高电子温度条件下，电子热运动对环向干涉仪/偏振仪（TIP）和极向偏振仪（PoPola）诊断所进行的相位测量的影响将十分显著，必须予以精确处理，否则测量精度将无法满足ITER运行所规定的指标要求。我们计算了沿切向和弦向路径传播的电磁波在干涉相位和偏振态方面所受的电子热修正，并将其纳入描述偏振态演化的斯托克斯矢量方程中。尽管在电子温度Te ≃ 1 keV时这些修正量较小，但在Te ⩾ 10 keV时已变得相当可观。此前仅考虑τ = Te/mec2一阶线性项的模型其精度可能不足；我们提出了包含τ2阶修正的更为精确的模型，以满足ITER中TIP和PoPola诊断所需的高精度要求。对温度效应的恰当处理将确保在ITER及DEMO等聚变装置中，对干涉测量和偏振测量结果进行更为准确的解读。对于燃烧等离子体而言，采用精确的解析表达式尤为重要，因为在此类装置中将利用多种干涉测量技术实现时间分辨率约为1 ms的实时反馈控制，以调节热核燃烧速率并监测/控制安全因子剖面。