Diocotron Modes in Pulsar Magnetospheres: Charge Diffusion and Implications for Radio Emission Variability
Year: 2026
Type: article
Abstract: The diocotron instability is a nonaxisymmetric plasma instability that should occur generically in the differentially rotating equatorial plane of pulsar magnetospheres. We present a series of 3D particle-in-cell (PIC) simulations of the diocotron instability in aligned and oblique pulsars. The instability grows on timescales of the rotation period and develops a strong, stable m = 1 mode, corresponding to a rotating, dipolar charge asymmetry in the equatorial disk. Stochastic fluctuations in the diocotron-mode amplitude and pattern speed drive cross-field diffusion that can rapidly transport charges through the closed zone toward the light cylinder. In the nonlinear stage, the m = 1 mode produces electric field perturbations which can modulate the polar-cap potential drop and the emission-beam angle, with possible connections to pulsar variability such as nulling, periodic amplitude modulation, and drifting subpulses.
Source: The Astrophysical Journal
Authors: Matthew Goodbred, Anatoly Spitkovsky
Institution: Princeton University
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $4,499
OpenAlex ID: W7163325812