Robust dynamic mitigation of instabilities

TL;DR

This paper demonstrates that a dynamic instability mitigation mechanism in plasma physics is robust against variations in perturbation parameters, and can effectively control instability growth when the phase of perturbations is known.

Contribution

The paper extends previous work by analyzing the robustness of the dynamic mitigation mechanism against changes in phase, amplitude, and wavelength of wobbling perturbations.

Findings

Mitigation mechanism is robust to phase, amplitude, and wavelength variations.

Controlling perturbation phase allows effective instability suppression.

Superposition of perturbations can mitigate growth when phase is known.

Abstract

A dynamic mitigation mechanism for instability growth was proposed and discussed in the paper [Phys. Plasmas 19, 024503 (2012)]. In the present paper the robustness of the dynamic instability mitigation mechanism is discussed further. The results presented here show that the mechanism of the dynamic instability mitigation is rather robust against changes in the phase, the amplitude and the wavelength of the wobbling perturbation applied. Generally instability would emerge from the perturbation of the physical quantity. Normally the perturbation phase is unknown so that the instability growth rate is discussed. However, if the perturbation phase is known, the instability growth can be controlled by a superposition of perturbations imposed actively: if the perturbation is induced by, for example, a driving beam axis oscillation or wobbling, the perturbation phase could be controlled and the instability growth is mitigated by the superposition of the growing perturbations.