Numerical Study of Instabilities Driven by Energetic Neutral Beam Ions in NSTX

Belova, E. V. ; Gorelenkov, N. N. ; Cheng, C. Z. ; Fredrickson, E. D.

Princeton University. Plasma Physics Laboratory.

关键词: Numerical Simulation;    Cyclotron Resonance;    70 Plasma Physics And Fusion Technology;    43 Particle Accelerators;    Anisotropy;   

DOI  :  10.2172/814697
RP-ID  :  PPPL-3832
RP-ID  :  AC02-76CH03073
RP-ID  :  814697

美国|英语

来源: UNT Digital Library

【 摘 要 】

Recent experimental observations from NSTX [National Spherical Torus Experiment] suggest that many modes in a subcyclotron frequency range are excited during neutral-beam injection (NBI). These modes have been identified as Compressional Alfven Eigenmodes (CAEs) and Global Alfven Eigenmodes (GAEs), which are driven unstable through the Doppler-shifted cyclotron resonance with the beam ions. The injection velocities of the NBI ions in NSTX are large compared to Alfven velocity, V(sub)0 > 3V(sub)A, and a strong anisotropy in the fast-ion pitch-angle distribution provides the energy source for the instabilities. Recent interest in the excitation of Alfven Eigenmodes in the frequency range omega less than or approximately equal to omega(sub)ci, where omega(sub)ci is the ion cyclotron frequency, is related to the possibility that these modes can provide a mechanism for direct energy transfer from super-Alfvenic beam ions to thermal ions. Numerical simulations are required in order to find a self-consistent mode structure, and to include the effects of finite-Larmor radius (FLR), the nonlinear effects, and the thermal plasma kinetic effects.