This paper presents the penetration of n = 2 magnetic field perturbations, where n is the toroidal mode number. The n = 2 intrinsic error field (IEF) is measured in an ohmic heating plasma using the compass scan method, i.e. the toroidal asymmetry in the threshold current for the penetration of n = 2 resonant magnetic perturbations (RMPs). Its amplitude is 55.5A in equivalent coil current or B _r,3/2 = 0.1G and the toroidal phase of the IEF is around 170.6 (129). Phasing scans (scans of the phase difference between the upper and lower coil currents) of the n = 2 RMPs are carried out to obtain the effects of the n = 2 spectrum on field penetration. The observed dependence of the field penetration on the spectrum is consistent with those of simulations using the MARS-F code. One of the interesting phenomena is that the n = 2 mode often stimulates an n = 1 mode. The dominant poloidal harmonic of the n = 1 mode is m = 2, and the dominant poloidal harmonic of the n = 2 mode is m = 3. The evolution of the n = 1 mode has two stages, i.e., an initial small island growth stage, and a later saturation stage. In the initial stage, the amplitude of the n = 1 magnetic island grows, while the phase remains fixed. When the amplitude of the magnetic island exceeds a certain threshold, it enters the second stage, in which the magnetic island is locked into another phase and its amplitude starts to saturate. The phase in the initial small island stage depends linearly on the phase of the applied n = 2 RMP, which suggests that the n = 2 mode is directly driven by the coupling between the n = 1 and n = 2 modes. The phase in the second stage is either locked to the phase close to the previously measured n = 1 IEF, or is locked to the phase close to the n = 2 response field. This suggests that the final phase of the n = 1 mode depends on competition between the locking effect induced by the n = 1 IEF and the nonlinear coupling effect between the two modes. This might be an issue in the MHD control application using high-n RMPs in the future ITER device.

本文介绍了n = 2 磁场扰动的穿透，其中n是环形模式数。所述Ñ = 2固有误差字段（IEF）是使用罗盘扫描方法中的欧姆加热血浆中测得的，即在对渗透阈值电流在环形不对称Ñ = 2层谐振磁场扰动（的RMP）。在等效线圈电流或B _r,3/2 = 0.1G 时，其振幅为 55.5A，IEF 的环形相位约为 170.6 (129)。逐步扫描中的（上和下线圈电流之间的相位差的扫描）ñ = 2个的RMP被执行，以获得Ë所述的ffects Ñ= 2 场穿透光谱。观察到的场穿透对光谱的依赖性与使用 MARS-F 代码的模拟一致。有趣的现象之一是n = 2 模式通常会激发n = 1 模式。n = 1模式的主导极向谐波为m = 2，n = 2模式的主导极向谐波为m = 3。n = 1模式的演变有两个阶段，即初始小岛增长阶段，以及后期的饱和阶段。在初始阶段，n的幅值= 1 磁岛增长，而相位保持固定。当磁岛的振幅超过一定阈值时，进入第二阶段，磁岛被锁定到另一个相位，其振幅开始饱和。初始小岛阶段的相位与施加的n = 2 RMP的相位线性相关，这表明n = 2 模式直接由n = 1 和n = 2 模式之间的耦合驱动。第二级中的相位要么锁定到接近先前测量的n = 1 IEF 的相位，要么锁定到接近n = 2 响应场的相位。这表明n的最后阶段= 1 模式取决于n = 1 IEF引起的锁定效应与两种模式之间的非线性耦合效应之间的竞争。这可能是未来 ITER 设备中使用高n RMP的 MHD 控制应用程序中的一个问题。