Particle-In-Cell Simulations of Pulsar Magnetospheres using WarpX

The plasma composition and structure of pulsar magnetospheres and the physical processes that drive particle acceleration are not well understood. Global pulsar magnetosphere simulations are required to answer these questions. However, resolving the current sheet skin-depth which is O(~10⁶) smaller than the pulsar radius for realistic systems, is intractable even on large supercomputers. Thus, the magnetic field strength in global PIC simulations is typically scaled-down restricting the maximum energy of the charged particles. We will present the effect of scaling down the magnetic field on particle acceleration, energy dissipation, and Poynting flux. We use WarpX, a highly scalable, electromagnetic PIC code with advanced algorithms to mitigate numerical artifacts in mesh-refinement simulations. We will also present 3D simulations to study the effect of pulsar obliquity and plasma injection rate on the plasma structure and Poynting flux. Additionally, we explore the use of ultra high-order spectral methods (PSATD) to perform pulsar magnetosphere simulations and compare its accuracy and performance with traditional finite-difference methods.