Bécoulet M, Orain F, Huijsmans G T A, Pamela S, Cahyna P, Hoelzl M, Garbet X, Franck E, Sonnendrücker E, Dif-Pradalier G, Passeron C, Latu G, Morales J, Nardon E, Fil A, Nkonga B, Ratnani A, Grandgirard V
CEA, IRFM, 13108 Saint-Paul-Lez-Durance, France.
ITER Organization, Route de Vinon-sur-Verdon, 13067 Saint-Paul-Lez-Durance, France.
Phys Rev Lett. 2014 Sep 12;113(11):115001. doi: 10.1103/PhysRevLett.113.115001. Epub 2014 Sep 8.
A possible mechanism of edge localized modes (ELMs) mitigation by resonant magnetic perturbations (RMPs) is proposed based on the results of nonlinear resistive magnetohydrodynamic modeling using the jorek code, realistic JET-like plasma parameters and an RMP spectrum of JET error-field correction coils (EFCC) with a main toroidal number n=2 were used in the simulations. Without RMPs, a large ELM relaxation is obtained mainly due to the most unstable medium-n ballooning mode. The externally imposed RMP drives nonlinearly the modes coupled to n=2 RMP which produce small multimode relaxations, mitigated ELMs. The modes driven by RMPs exhibit a tearinglike structure and produce additional islands. Mitigated ELMs deposit energy into the divertor mainly in the structures ("footprints") created by n=2 RMPs, however, slightly modulated by other nonlinearly driven even harmonics. The divertor power flux during a ELM phase mitigated by RMPs is reduced almost by a factor of 10. The mechanism of ELM mitigation by RMPs proposed here reproduces generic features of high collisionality RMP experiments, where large ELMs are replaced by small, much more frequent ELMs or magnetic turbulence. Total ELM suppression was also demonstrated in modeling at higher RMP amplitude.
基于使用jorek代码进行的非线性电阻磁流体动力学建模结果，提出了一种通过共振磁扰动（RMP）缓解边缘局域模（ELM）的可能机制。模拟中使用了类似JET的实际等离子体参数以及具有主环向模数n = 2的JET误差场校正线圈（EFCC）的RMP谱。在没有RMP的情况下，主要由于最不稳定的中等模数气球模而获得较大的ELM弛豫。外部施加的RMP非线性驱动与n = 2 RMP耦合的模式，这些模式产生小的多模弛豫，即缓解的ELM。由RMP驱动的模式呈现出撕裂状结构并产生额外的岛状物。缓解的ELM主要在由n = 2 RMP产生的结构（“足迹”）中将能量沉积到偏滤器中，不过会受到其他非线性驱动的偶次谐波的轻微调制。通过RMP缓解的ELM阶段期间的偏滤器功率通量几乎降低了10倍。这里提出的通过RMP缓解ELM的机制再现了高碰撞性RMP实验的一般特征，在这些实验中，大的ELM被小的、频率高得多的ELM或磁湍流所取代。在更高的RMP振幅下进行的建模中也证明了ELM的完全抑制。
