Onset, growth, and saturation of the current-driven ion cyclotron instability

Abstract

The temporal evolution of the current-driven electrostatic ion cyclotron instability was investigated experimentally. The critical destabilizing electron drift velocity for different values of mode phase velocity was measured. The phase velocity was changed by varying the effective plasma column length and hence the parallel wavelength. Ion cyclotron damping was observed to dominate over electron Landau damping at low phase velocities. The temporal growth rate was experimentally determined for several values of electron drift and found to agree very well with linear theory. The observed saturated mode amplitudes compare favorably with the saturation levels predicted by a theory of nonlinear stabilization due to wave induced collisions.

Nonlinear wave effects in laboratory plasmas: A comparison between theory and experiment

“…In particular, the experiments of Jensen et al (1969), which we discussed earlier in connection with echoes, gave evidence of diffusion of particle orbits due to the presence of turbulence. Further evidence of resonance broadening and its saturating effect upon instabilities (or its reduction of their growth rates) was obtairied recently by Correll et al (1975), Slusher et al (1976), Benford and Correll (1977, and Hershcovitch (1977). In the experiments of Slusher et al (1976) the saturation of the current-driven ion acoustic instability was studied.…”

Current Jumps and Hysteresis in a Single‐ended Q‐Machine in Connection with the Electrostatic Ion‐Cyclotron Instability

“…Generally, however, in earlier works the EICI amplitude was reported to grow gradually with Vc from the noise, i.e., the instability showed a "soft" onset (see e.g. [31], cf. also the references in [2]).…”

Asymmetric spectral broadening of modulated electrostatic ion‐cyclotron waves

“…Waves CDEIC waves grow exponentially from negligible amplitude by inverse electron Landau damping, described by linear theory [Drummond and Rosenbluth, 1962], that occurs when the electron distribution is displaced in velocity relative to the ion distribution. At sufficiently large wave amplitudes, nonlinear damping from an effective diffusion process (wave-induced collisions) broadens the wave-particle resonance [Correll et al, 1975;Durn and Dupree, 1970]. The magnitude of this damping is an increasing function of wave amplitude and so eventually the damping balances the growth at a steady-state amplitude.…”