Mechanism of the active divertor flux control by the supersonic-molecular-beam-injection with lower hybrid wave-induced magnetic perturbations on the EAST tokamak

Abstract

The redistribution of the divertor flux caused by the synergy of the supersonic-molecularbeam-injection (SMBI) and the magnetic perturbations induced by lower hybrid waves (LHWs), has been observed on the Experimental Advanced Superconducting Tokamak (EAST) (Li et al 2013 Nature Phys. 9 817). To reveal the physical mechanism, simulations with good agreements to the experimental findings are first performed by utilizing a self-consistent fluid 3D edge plasma Monte-Carlo code coupled to a kinetic neutral particle transport code. The ions and electrons originating from the ionization of injected neutral particles in the plasma edge flow along the magnetic flux tube towards to the divertor, thus directly increasing the divertor flux on the split strike lines in the footprint. Combining this with the multi-lobe structure of the edge magnetic topology, actively controlling the divertor flux can be realized by adjusting the SMBI position or the phase of the magnetic perturbations.

Integrated ELM and divertor power flux control using RMPs with low input torque in EAST in support of the ITER research plan

“…With the RMP application, the 3D magnetic topology change will introduce magnetic footprint splitting which can be observed as multiple spiral strike lines in divertor particle or heat fluxes [17][18][19][20][21] due to the intersection of lobes formed by the perturbed invariant manifolds with the divertor [20,22,23]. Initial experiments and simple modelling for EAST [24,25] and recent advanced modelling for ITER [26] indicate that control of divertor power fluxes near the separatrix strike point and in the off-separatrix strike point lobes by access to high recycling or radiative conditions can be impacted by the 3D edge magnetic field structure. Due to the 3D field effect, high recycling and radiative divertor conditions can be readily established near the separatrix strike point while secondary off-separatrix lobes remain in lower recycling conditions even when the divertor plasma at the separatrix is strongly detached [26].…”

Effects of a coherent mode on the redistribution of divertor particle flux in HL-2A H-mode plasmas

“…(LHWs) [6,7]. Supersonic molecular beam injection (SMBI) [8,9] and pellet injection [10,11] are also attractive ways to reduce the heat load, as reported in previous research.…”

Influence of the X-point location on edge plasma transport in the J-TEXT tokamak with a high-field-side single-null divertor

“…The EMC3 code applies an advanced Monte Carlo algorithm to solve the fluid equations. The code has been widely used in multiple devices, including stellarators and tokamaks such as W7-X [27], LHD [28][29][30][31][32], TEXTOR-DED [33], DIII-D [34], ASDEX-U [35], JET [36], TCV [37] and EAST [38][39][40][41][42][43][44]. In this work, the grid generator of EMC3-EIRENE is adapted to the J-TEXT axisymmetric HFS divertor configurations.…”