Experimental studies of instabilities and confinement of energetic particles on JET and MAST
Experimental studies of instabilities and confinement of energetic particles on JET and MAST
复制标题
JET 和 MAST 上高能粒子不稳定性和约束的实验研究
DOI：
10.1088/0029-5515/45/9/017
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发表时间：
2005
期刊：
影响因子：
3.3
通讯作者：
F. Zonca
中科院分区：
文献类型：
--
作者：
S. Sharapov;B. Alper;F. Andersson;Y. Baranov;H. Berk;L. Bertalot;D. Borba;C. Boswell;B. Breizman;R. Buttery;C. Challis;M. D. de Baar;P. D. de Vries;L. Eriksson;A. Fasoli;R. Galvão;V. Goloborod’ko;M. Gryaznevich;R. Hastie;N. Hawkes;P. Helander;V. Kiptily;G. Kramer;P. Lomas;J. Mailloux;M. Mantsinen;R. Martín;F. Nabais;M. Nave;R. Nazikian;J. Noterdaeme;M. Pekker;S. Pinches;T. Pinfold;S. Popovichev;P. Sandquist;D. Stork;D. Testa;A. Tuccillo;I. Voitsekhovich;V. Yavorskij;N. P. Young;F. Zonca
为了准备下一步燃烧等离子体装置，如 ITER，在欧洲联合环面 (JET) 和兆安培球形托卡马克 (MAST) 上，采用创新的诊断技术，在传统和剪切反转等离子体中对高能离子的不稳定性和限制进行了实验研究，探索了高能离子的广泛影响。本文介绍了当前燃烧等离子体相关研究设施的最新结果测试能力。使用 4He 束离子的三次谐波离子回旋共振加热 (ICRH) 产生“阿尔法尾”，已在 JET 上用于研究“无中子”环境中兆电子伏能量范围的 4He。根据快离子与 Be 和 C 杂质碰撞产生的核伽马射线发射，评估了 E ⩾ 1.7 MeV 的 4He 和 E ⩾ 500 keV 的 D 的 ICRH 加速离子的演化。首次在正向和强反向磁剪切放电中同时测量与 ITER 相关的快 4He 和快 D 离子的空间分布。 ICRH 加速的 3He 和 H 少数离子的时间分辨伽马射线诊断允许在不稳定的环形阿尔文本征模 (TAE) 和锯齿存在的情况下评估快离子分布函数的变化。在“龙卷风”模式下，检测到 E⩾ 5 MeV 质子的伽马射线强度显着降低。这被解释为“龙卷风”引起的快离子损失，其漂移轨道宽度 Δf 与托卡马克的小半径 a 相当。在相反的情况下进行的实验，Δf/a < 1，对于 E ⩾ 500 keV 的 ICRH 加速 3He 离子，显示了许多阿尔文本征模的激发，而快离子限制没有显着退化。实验发现，快速粒子对“怪物”锯齿的稳定作用在高功率离子回旋共振频率（ICRF）加热的低密度等离子体中失效。使用不同的 ICRF 相位研究了从“怪物”锯齿到短周期“草状”锯齿的转变，这些相位控制了 ICRF 加速离子的收缩效应和径向分布。在球形托卡马克 MAST 上研究了超阿尔芬束离子激发的不稳定性。由于 MAST 上的 β 值比 JET 上的更高，并且快离子的比例更高，因此观察到了更广泛的阿尔文不稳定性模式和非线性区域，包括导致快离子分布函数上形成空穴簇对的爆炸性 TAE 区域。 MAST 和 START 数据表明，随着 β 的增加，TAE 和线性调频模式的模式幅度和不稳定模式的数量都会减少。
In preparation for next step burning plasma devices such as ITER, experimental studies of instabilities and confinement of energetic ions were performed on Joint European Torus (JET) and on Mega-Amper Spherical Tokamak (MAST) with innovative diagnostic techniques, in conventional and shear-reversed plasmas, exploring a wide range of effects for energetic ions. A compendium of recent results testing capabilities of the present-day facilities for burning plasma relevant study is presented in this paper. ‘Alpha tail’ production using 3rd harmonic ion-cyclotron resonance heating (ICRH) of 4He beam ions has been employed on JET for studying 4He of the megaelectronvolt energy range in a ‘neutron-free’ environment. The evolution of ICRH-accelerated ions of 4He with E ⩾ 1.7 MeV and D with E ⩾ 500 keV was assessed from nuclear gamma-ray emission born by the fast ions colliding with Be and C impurities. A simultaneous measurement of spatial profiles of fast 4He and fast D ions relevant to ITER was performed for the first time in positive and strongly reversed magnetic shear discharges. Time-resolved gamma-ray diagnostics for ICRH-accelerated 3He and H minority ions allowed changes in the fast ion distribution function to be assessed in the presence of unstable toroidal Alfvén eigenmodes (TAEs) and sawteeth. A significant decrease of gamma-ray intensity from protons with E ⩾ 5 MeV was detected during the ‘tornado’ modes. This was interpreted as ‘tornado’-induced loss of fast ions with the drift orbit width, Δf, comparable to the minor radius of tokamak a. Experiments performed in the opposite case, Δf/a ≪ 1, for ICRH-accelerated 3He ions with E ⩾ 500 keV, have shown excitation of numerous Alfvén eigenmodes without a significant degradation of the fast ion confinement. The stabilizing effect of fast particles on ‘monster’ sawteeth was experimentally found to fail in low-density plasmas with high power ion cyclotron resonance frequency (ICRF)-heating. The transition from the ‘monster’ to short-period ‘grassy’ sawteeth was investigated with different ICRF phasing, which controls the pinch-effect and radial distribution of ICRF-accelerated ions. Instabilities excited by super-Alfvénic beam ions were investigated on the spherical tokamak MAST. Due to higher values of β and a higher proportion of fast ions on MAST than on JET, a wider variety of modes and nonlinear regimes for the Alfvén instabilities were observed, including the explosive TAE-regimes leading to the formation of hole-clump pairs on the fast ion distribution function. The MAST and START data showed that TAE and chirping modes decrease both in their mode amplitudes and in the number of unstable modes with increasing β.
影响因子：
3.3
作者：
Shimada, M.;Campbell, D. J.;Sipps, A. C. C.
通讯作者：
Sipps, A. C. C.