Ko J
National Fusion Research Institute, Daejeon 34133, South Korea.
Rev Sci Instrum. 2016 Nov;87(11):11E541. doi: 10.1063/1.4962058.
The sensitivity of the pitch angle profiles measured by the motional Stark effect (MSE) diagnostic to the evolution of the safety factor, q, profiles during the tokamak sawtooth events has been investigated for Korea Superconducting Tokamak Advanced Research (KSTAR). An analytic relation between the tokamak pitch angle, γ, and q estimates that Δγ ∼ 0.1° is required for detecting Δq ∼ 0.05 near the magnetic axis (not at the magnetic axis, though). The pitch angle becomes less sensitive to the same Δq for the middle and outer regions of the plasma (Δγ ∼ 0.5°). At the magnetic axis, it is not straightforward to directly relate the γ sensitivity to Δq since the gradient of γ(R), where R is the major radius of the tokamak, is involved. Many of the MSE data obtained from the 2015 KSTAR campaign, when calibrated carefully, can meet these requirements with the time integration down to 10 ms. The analysis with the measured data shows that the pitch angle profiles and their gradients near the magnetic axis can resolve the change of the q profiles including the central safety factor, q, during the sawtooth events.
针对韩国超导托卡马克先进研究装置（KSTAR），研究了通过运动斯塔克效应（MSE）诊断测量的俯仰角分布对托卡马克锯齿事件期间安全因子q分布演变的灵敏度。托卡马克俯仰角γ与q之间的解析关系估计，在磁轴附近（不过不是在磁轴处）检测到Δq ∼ 0.05需要Δγ ∼ 0.1°。对于等离子体的中部和外部区域，俯仰角对相同的Δq变得不太敏感（Δγ ∼ 0.5°）。在磁轴处，由于涉及γ(R)的梯度（其中R是托卡马克的大半径），将γ灵敏度直接与Δq相关联并不简单。从2015年KSTAR实验中获得的许多MSE数据，经过仔细校准后，在时间积分低至10 ms时可以满足这些要求。对测量数据的分析表明，磁轴附近的俯仰角分布及其梯度可以分辨锯齿事件期间包括中心安全因子q在内的q分布的变化。
