Neutral beam injection into a plasma with negative central shear produces a rich spectrum of toroidicity-induced and reversed-shear Alfvén eigenmodes in the DIII-D tokamak. The application of fast-ion Dα (FIDA) spectroscopy shows that the central fast-ion profile is flattened in the inner half of the discharge. Neutron and equilibrium measurements corroborate the FIDA data. The temporal evolution of the current profile is also strongly modified. Studies in similar discharges show that flattening of the profile correlates with the mode amplitude and that both types of Alfvén modes correlate with fast-ion transport. Calculations by the ORBIT code do not explain the observed fast-ion transport for the measured mode amplitudes, however. Possible explanations for the discrepancy are considered.
中性束注入到具有负中心剪切的等离子体中，在DIII-D托卡马克中产生了丰富的环向性诱导和反剪切阿尔芬本征模谱。快离子Dα（FIDA）光谱的应用表明，中心快离子分布在放电内部一半区域被展平。中子和平衡测量 corroborate FIDA数据。电流分布的时间演化也受到强烈修正。在类似放电中的研究表明，分布展平与模振幅相关，且两类阿尔芬模均与快离子输运相关。然而，ORBIT代码的计算并不能解释所测模振幅下的快离子输运。对此差异的可能解释进行了探讨。