Prediction of Nonlinear Evolution Character of Energetic-Particle-Driven   Instabilities
  A general criterion is proposed and found to successfully predict the emergence of chirping oscillations of unstable Alfv\'enic eigenmodes in tokamak plasma experiments. The model includes realistic eigenfunction structure, detailed phase-space dependences of the instability drive, stochastic scattering and the Coulomb drag. The stochastic scattering combines the effects of collisional pitch angle scattering and micro-turbulence spatial diffusion. The latter mechanism is essential to accurately identify the transition between the fixed-frequency mode behavior and rapid chirping in tokamaks and to resolve the disparity with respect to chirping observation in spherical and conventional tokamaks. 
Vinicius Duarte, Herbert Berk, Nikolai Gorelenkov, William Heidbrink,   Gerrit Kramer, Raffi Nazikian, David Pace, Mario Pod...
physics.plasm-ph