Frequency Sweeping in Plasmas due to Phase‐Space Structures

Abstract

This review examines the nonlinear dynamics of a plasma near marginal stability where there is a balance between the destabilizing resonant kinetic drive and the stabilizing dissipation in the background plasma. Depending on the degree of extrinsic stochasticity of the resonant particles, different saturated states are analytically described. At low enough stochasticity, an explosive self‐similar solution is predicted. Numerical simulation shows this explosive behavior is a precursor to the formation of phase space structures in the form of holes and clumps, which cause up an down shifted frequency sweeping due to plasma dissipation. Experimental evidence for the predicted behavior is discussed.

Keywords:

• Frequency sweeping
• holes and clumps
• instability threshold
• saturated states

Acknowledgments

I am strongly indebted to my collaborators over the past decade for the development of this problem; especially to Dr. B. N. Breizman with whom collaboration was particularly close.