Fast-ion losses induced by ELMs and externally applied magnetic perturbations in the ASDEX Upgrade tokamak
Fast-ion losses induced by ELMs and externally applied magnetic perturbations in the ASDEX Upgrade tokamak
复制标题
DOI：
10.1088/0741-3335/55/12/124014
复制
发表时间：
2013-12
影响因子：
2.2
通讯作者：
M. Garcia-Muñoz;S. Äkäslompolo;P. Marné;M. Dunne;R. Dux;T. Evans;N. Ferraro;S. Fietz;C. Fuchs-C.
中科院分区：
文献类型：
--
作者：
M. Garcia-Muñoz;S. Äkäslompolo;P. Marné;M. Dunne;R. Dux;T. Evans;N. Ferraro;S. Fietz;C. Fuchs-C.
在ASDEX升级托卡马克装置上，利用多个快离子损失探测器（FILD）对边缘局域模（ELMs）和ELM抑制线圈引起的快离子损失进行了相空间时间分辨测量。在ELM期间，通过几个FILD在不同的环形和极向位置测量快离子损失的丝状突发。外部施加的磁扰动（MP）对等离子体轮廓，包括快离子，在高碰撞等离子体与减轻ELMs的影响很小。然而，在低密度/碰撞性和q95等离子体与外部施加MP的强烈影响，观察到等离子体密度，旋转和快离子。在缓解/抑制I型ELMs的外部施加的MP，在ELMs过程中观察到的大的快离子脉冲串被替换为稳定的快离子损失与宽带频率和幅度高达一个数量级高于中性束注入（NBI）提示损失信号没有MP。在不同位置处的多个FILD测量表明，由于静态3D场导致的快离子损失被定位在第一壁的某些部分上，而不是环形地/极面地均匀分布。测得的快离子损失显示出广泛的能量和俯仰角范围，通常在探索整个基座/刮除层（SOL）的香蕉轨道上。测量被用来估计与MP引起的快离子损失的热负荷。FILD探测器头和周围墙壁上的热负荷与MP相比可以高达六倍。当施加3D场并观察到密度泵出时，通常通过快离子D-α（FIDA）光谱测量等离子体中快离子含量的增强。MP阶段期间的较低密度也导致更深的束沉积，其中在束发射的最大值中向内的径向位移为0.2cm。轨道模拟用于测试三维场平衡重建的不同模型，包括真空表示，自由边界NEMEC代码和双流体M3 D-C1代码，占等离子体响应。引导中心模拟预测的最大水平的损失，10.22.6%，与NEMEC三维平衡。全轨道模拟高估了3D真空场中的损失水平，损失了15%的NBI离子。
Phase-space time-resolved measurements of fast-ion losses induced by edge localized modes (ELMs) and ELM mitigation coils have been obtained in the ASDEX Upgrade tokamak by means of multiple fast-ion loss detectors (FILDs). Filament-like bursts of fast-ion losses are measured during ELMs by several FILDs at different toroidal and poloidal positions. Externally applied magnetic perturbations (MPs) have little effect on plasma profiles, including fast-ions, in high collisionality plasmas with mitigated ELMs. A strong impact on plasma density, rotation and fast-ions is observed, however, in low density/collisionality and q95 plasmas with externally applied MPs. During the mitigation/suppression of type-I ELMs by externally applied MPs, the large fast-ion bursts observed during ELMs are replaced by a steady loss of fast-ions with a broad-band frequency and an amplitude of up to an order of magnitude higher than the neutral beam injection (NBI) prompt loss signal without MPs. Multiple FILD measurements at different positions, indicate that the fast-ion losses due to static 3D fields are localized on certain parts of the first wall rather than being toroidally/poloidally homogeneously distributed. Measured fast-ion losses show a broad energy and pitch-angle range and are typically on banana orbits that explore the entire pedestal/scrape-off-layer (SOL). Infra-red measurements are used to estimate the heat load associated with the MP-induced fast-ion losses. The heat load on the FILD detector head and surrounding wall can be up to six times higher with MPs than without 3D fields. When 3D fields are applied and density pump-out is observed, an enhancement of the fast-ion content in the plasma is typically measured by fast-ion D-alpha (FIDA) spectroscopy. The lower density during the MP phase also leads to a deeper beam deposition with an inward radial displacement of ≈2 cm in the maximum of the beam emission. Orbit simulations are used to test different models for 3D field equilibrium reconstruction including vacuum representation, the free boundary NEMEC code and the two-fluid M3D-C1 code which account for the plasma response. Guiding center simulations predict the maximum level of losses, ≈2.6%, with NEMEC 3D equilibrium. Full orbit simulations overestimate the level of losses in 3D vacuum fields with ≈15% of lost NBI ions.