Destabilizing Effect of Dynamical Friction on Fast-Particle-Driven Waves in a Near-Threshold Nonlinear Regime
- Physics Department, Imperial College, London, SW7 2AZ (United Kingdom)
The nonlinear evolution of waves excited by the resonant interaction with energetic particles, just above the instability threshold, is shown to depend on the type of relaxation process that restores the unstable distribution function. When dynamical friction dominates over diffusion in the phase space region surrounding the wave-particle resonance, an explosive evolution of the wave is found to be the only solution. This is in contrast with the case of dominant diffusion when the wave may exhibit steady-state, amplitude modulation, chaotic and explosive regimes near marginal stability. The experimentally observed differences between Alfvenic instabilities driven by neutral beam injection and those driven by ion-cyclotron resonance heating are interpreted.
- OSTI ID:
- 21316714
- Journal Information:
- Physical Review Letters, Vol. 102, Issue 19; Other Information: DOI: 10.1103/PhysRevLett.102.195003; (c) 2009 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 0031-9007
- Country of Publication:
- United States
- Language:
- English
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