Combined neutral beam injection and fast wave heating at thefourth cyclotron harmonic produce an energetic deuterium beam ion tail in theDIII-D tokamak. When the concentration of thermal hydrogen exceeds ∼5%, the beam ion absorption is suppressed in favour of second harmonichydrogen absorption. As theoretically expected, the beam absorption increaseswith beam ion gyro-radius; also, central absorption at thefifth harmonic is weaker than central absorption at the fourth harmonic.For central heating at the fourth harmonic, an energetic, perpendicular,beam population forms inside the q = 1 surface. The beam ion tail transientlystabilizes the sawtooth instability but destabilizes toroidicity induced Alfvén eigenmodes (TAEs). Saturation of the central heating correlates with theonset of the TAEs. Continued expansion of the q = 1 radius eventuallyprecipitates a sawtooth crash; complete magnetic reconnection is observed.
在DIII-D托卡马克中，中性束注入与第四次谐波快波加热相结合，产生了高能氘束离子尾部。当热氢浓度超过约5%时，束离子吸收被抑制，转而支持第二次谐波氢吸收。正如理论预期，束吸收随束离子回旋半径增大而增强；此外，中心区域在第五次谐波处的吸收弱于第四次谐波处。对于第四次谐波的中心加热，在q=1面内形成了高能垂直束离子群。该束离子尾部瞬态稳定了锯齿不稳定性，但 destabilizes 了环形阿尔芬本征模（TAEs）。中心加热的饱和与TAEs的出现相关。q=1半径的持续扩展最终触发了锯齿崩溃；观察到完全磁重联。