A comparison of the influence of plasmoid-drift mechanisms on plasma fuelling by cryogenic pellets in ITER and Wendelstein 7-X

Nuclear Fushion

article

A. Matsuyama¹  K.J. McCarthy²  B. Pégourié³  Y. Turkin⁴  N. Panadero²  F. Koechl⁵  A.R. Polevoi⁶  J. Baldzuhn⁴  C.D. Beidler⁴  P.T. Lang⁴  A. Loarte⁶ 

[1] Rokkasho Fusion Institute, National Institutes for Quantum and Radiological Science and Technology;Laboratorio Nacional de Fusión;CEA;Max-Planck-Institut für Plasmaphysik;Culham Centre for Fusion Energy, Culham Science Centre;ITER Organization

关键词: pellet;    plasmoid;    drift;    stellarator;    tokamak;    pellet fuelling;   

DOI  :  10.1088/1741-4326/acbc34

来源: Institute of Physics Publishing Ltd.

【 摘 要 】

Pellet injection is the most promising technique to achieve efficient plasma core fuelling, key for attaining stationary scenarios in large magnetic confinement fusion devices. In this paper, the injection of pellets with different volumes and speeds into standard plasma scenarios in ITER (tokamak) and Wendelstein 7-X (stellarator) is studied by modeling the pellet ablation and particle deposition, focusing on the evaluation of the expected differences in pellet plasmoid drifts in tokamaks and stellarators. Since the efficiency of the damping-drift mechanisms is predicted to depend on the magnetic configuration, device-specific characteristics are expected for the temporal evolution of the plasmoid drift acceleration. For instance, plasmoid-internal Pfirsch–Schlüter currents dominate the drift damping process for stellarators, while plasmoid-external currents are more relevant for tokamaks. Also, relatively larger drifts are in principle expected for W7-X due to higher field gradients in relation to machine dimensions. However, shorter plasmoid-internal charge reconnection lengths result in the drift damping due to internal Pfirsch–Schlüter currents being more effective than in a tokamak. Therefore, the average relative drift displacement during the whole plasmoid homogenization maya prioribe comparable in both magnetic configurations. Moreover, High Field Side (HFS) injection is expected to be highly advantageous to maximize pellet particle deposition in ITER, whereas it may only be beneficial in medium to highβenvironments in W7-X. Finally, there may be means for the optimization of pellet injection configurations in both ITER and W7-X for the considered plasma scenarios despite the sizeable differences in the relative importance of the mechanisms of plasmoid drift acceleration and deceleration in play.

【 授权许可】

Unknown