Core Concepts
This research paper investigates the collisionless tearing instability in relativistic pair plasmas using 2D particle-in-cell (PIC) simulations, confirming and extending existing theoretical models for a wide range of temperatures and drift velocities.
Stats
For a/ρL,C = 2.5, the simulations used 1024 particles-per-cell, Ly/a = 20.5, Lx = Ly/2, and a resolution of 18.6 grid cells per a.
For a/ρL,C = 5, the simulations used 4096 particles-per-cell to mitigate numerical heating, maintaining the same system size, resolution, and time step.
The dominant mode in the linear stage was observed at ka ≈ 0.6, consistent with the theoretical prediction of ka = 1/√3 ≈ 0.58.
In the case with a/ρL,C = 5 and T/mec2 = 0.005, increasing the simulation box length to Lx = Ly resulted in a fast-growing nonlinear stage, while the growth saturated early for Lx = Ly/2.
Introducing a background density of nb/n0 = 0.1 in the simulation with a/ρL,C = 5, T/mec2 = 0.005, and Lx = Ly led to a slower nonlinear growth rate, as predicted.
Quotes
"A quite general theoretical model for this instability that is relevant for all the assumptions that we are considering was derived in Zelenyi & Krasnosel’skikh (1979)."
"In this paper, we show using PIC simulations that Zelenyi’s model, including Hoshino’s extension, gives quite accurate results for a wide range of parameters."
"While in the classical regime, a wider ρL,C/a can occur if either T/mec2 or ud/c change, in the relativistic regime, a wider ρL,R/a implies a faster ud/c."