Edge localized mode control using n  =  1 resonant magnetic perturbation in the EAST tokamak

Abstract

A set of in-vessel resonant magnetic perturbation (RMP) coil has been recently installed in EAST. It can generate a range of spectrum, and there is a relatively large window for edge localized mode (ELM) control according to the vacuum field modeling of the edge magnetic island overlapping area. Observation of mitigation and suppression of ELM in slow rotating plasmas during the application of an n = 1 RMP is presented in this paper. Strong ELM mitigation effect is observed in neutral beam injection heating plasmas. The ELM frequency increases by a factor of 5, and the crash amplitude and the particle flux are effectively reduced by a similar factor. Clear density pump-out and magnetic braking effects are observed during the application of RMP. Footprint splitting is observed during ELM mitigation and agrees well with vacuum field modelling. Strong ELM mitigation happens after a second sudden drop of plasma density, which indicates the possible effect due to field penetration of the resonant harmonics near the pedestal top, where the electron perpendicular rotation becomes flat and close to zero after the application of RMP. ELM suppression is achieved in a resonant window during the scan of the n = 1 RMP spectrum in radio-frequency (RF) dominant heating plasmas. The best spectrum for ELM suppression is consistent with the resonant peak of RMP by taking into account of linear magnetohydrodynamics plasma response. There is no mode locking during the application of n = 1 RMP in ELMy H-mode plasmas, although the maximal coil current is applied.

Recent advances in EAST physics experiments in support of steady-state operation for ITER and CFETR

“…This covers a q95 window from 3. The maximal resonance in plasma response field modelled by linear MHD code MARS-F agrees with the optimal phasing for ELM control during the scan the phasing (the phase difference between the upper and lower coil current) [8]. Recently, a multi-modal plasma response to applied non-axisymmetric fields has been found in EAST tokamak plasmas.…”

Recent progress in Chinese fusion research based on superconducting tokamak configuration

“…Uncontrolled type I ELM can cause significant damage to the materials of ITER PFCs in H-mode plasmas. 41 Therefore, ELM control is an important issue in tokamak fusion research.…”

Plasma response to resonant magnetic perturbations near rotation zero-crossing in low torque plasmas

“…EAST, as a superconducting tokamak, possesses the features such as low torque and ITER-like divertors [36,37]. An example plasma equilibrium of EAST discharge 52340 at 3150 ms are reconstructed with K-EFIT [13] is used as a reference. Figure 1 shows the radial profiles of plasma density (N e , dotted line), temperature of ion (T i , dashed-dotted line) and electron (T e , dashed line), toroidal rotation (ω φ , solid line) and safety factor (q, triangle line).…”

“…ELM suppression by resonant magnetic perturbation (RMP) has been obtained widely in DIII-D [3], KSTAR [4], EAST [5] and AUG [6], besides mitigation obtained in JET [7] and MAST [8]. Linear models revealed the optimal spectrum of RMP for ELM control of which the figure of merit is edge resonant component of plasma response or plasma surface displacement near the X-points [9,10,11,12,13,14]. Using the experiments in high n RMP and high q 95 , a better criterion is found, i.e.…”