Siegfried Glenzer, Postdoctoral Faculty Sponsor
Enhancement of the Nonresonant Streaming Instability by Particle Collisions
PHYSICAL REVIEW LETTERS
2022; 128 (11): 115101
Streaming cosmic rays can power the exponential growth of a seed magnetic field by exciting a nonresonant instability that feeds on their bulk kinetic energy. By generating the necessary turbulent magnetic field, it is thought to play a key role in the confinement and acceleration of cosmic rays at shocks. In this Letter we present hybrid-particle-in-cell simulations of the nonresonant mode including Monte Carlo collisions, and investigate the interplay between the pressure anisotropies produced by the instability and particle collisions in the background plasma. Simulations of poorly ionized plasmas confirm the rapid damping of the instability by proton-neutral collisions predicted by linear fluid theory calculations. In contrast we find that Coulomb collisions in fully ionized plasmas do not oppose the growth of the magnetic field, but under certain conditions suppress the pressure anisotropies and actually enhance the magnetic field amplification.
View details for DOI 10.1103/PhysRevLett.128.115101
View details for Web of Science ID 000782905600004
View details for PubMedID 35363004