De Bock M F M, Conway N J, Walsh M J, Carolan P G, Hawkes N C
EURATOM/UKAEA Fusion Association, Culham Science Centre, Abingdon OX14 3DB, United Kingdom.
Rev Sci Instrum. 2008 Oct;79(10):10F524. doi: 10.1063/1.2966459.
A multichord motional Stark effect (MSE) system has recently been built on the MAST tokamak. In MAST the pi and sigma lines of the MSE spectrum overlap due to the low magnetic field typical for present day spherical tokamaks. Also, the field curvature results in a large change in the pitch angle over the observation volume. The measured polarization angle does not relate to one local pitch angle but to an integration over all pitch angles in the observation volume. The velocity distribution of the neutral beam further complicates the measurement. To take into account volume effects and velocity distribution, an ab initio code was written that simulates the MSE spectrum on MAST. The code is modular and can easily be adjusted for other tokamaks. The code returns the intensity, polarized fraction, and polarization angle as a function of wavelength. Results of the code are presented, showing the effect on depolarization and wavelength dependence of the polarization angle. The code is used to optimize the design and calibration of the MSE diagnostic.
最近在MAST托卡马克装置上构建了一个多弦运动斯塔克效应（MSE）系统。在MAST装置中，由于当今球形托卡马克典型的低磁场，MSE光谱的π线和σ线相互重叠。此外，场曲率导致观测体积内的俯仰角发生很大变化。测得的极化角并不与一个局部俯仰角相关，而是与观测体积内所有俯仰角的积分相关。中性束的速度分布进一步使测量变得复杂。为了考虑体积效应和速度分布，编写了一个从头算代码，用于模拟MAST上的MSE光谱。该代码是模块化的，可以很容易地针对其他托卡马克进行调整。该代码返回强度、极化分数和极化角作为波长的函数。给出了代码的结果，显示了对去极化的影响以及极化角的波长依赖性。该代码用于优化MSE诊断的设计和校准。
