Dynamical feedback of the curvature drift instability on its saturation process

TL;DR

This paper analyzes how plasma dynamics influence the saturation of the curvature drift instability in pulsar magnetospheres, revealing a process where magnetic field twisting leads to force-free plasma configurations.

Contribution

It provides an analytical study of the plasma-driven saturation mechanism of the curvature drift instability near the pulsar light cylinder.

Findings

Parametric excitation of drift modes by rotational energy.

Generation of a toroidal magnetic field component.

Saturation occurs when plasma particles experience no net forces.

Abstract

We investigate the reconstruction of pulsar magnetospheres close to the light cylinder surface to study the curvature drift instability (CDI) responsible for the twisting of magnetic field lines in the mentioned zone. The influence of plasma dynamics on the saturation process of the CDI is studied. On the basis of the Euler, continuity, and induction equations, we derive the increment of the CDI and analyze parametrically excited drift modes. The dynamics of the reconstruction of the pulsar magnetosphere is studied analytically. We show that there is a possibility of a parametrically excited rotational-energy pumping-process in the drift modes. It is indicated by the generation of a toroidal component of the magnetic field that transforms the field lines into such a configuration, in which plasma particles do not experience any forces. At this stage, the instability process saturates and the further amplification of the toroidal component to the magnetic field lines is suspended.