Objective: The purpose of this project is to develop plasma simulation codes on parallel computers. The codes are useful for investigating kinetic plasma processes associated with global space plasma phenomena. The specific applications include magnetic reconnection processes responsible for magnetic substorms in the Earth's magnetosphere. Due to limitations in computer capabilities, particle modeling of magnetic reconnection phenomena has not been conducted.
Approach: The particle-in-cell (PIC) codes are developed by solving Maxwell equations together with particles to represent the charge and current carriers. The particles are advanced in time using the particle equations of motion with the self-consistently calculated electric and magnetic fields. We will use the hybrid PIC approach, in which electrons are considered as fluid and ions are treated as particles. Using this approach, effects that are outside of the scope of the fluid description and essential to many space plasma physics problems can be calculated.
A key element of developing PIC codes on parallel computers is the gather-scatter scheme. The gather-scatter scheme is used to communicate between particle quantities (like charge and current densities) and the grid quantities (like electric and magnetic fields).
To understand simulation results of magnetic reconnection in the Earth's magnetosphere, we rely on diagnostic tools. One useful diagnostic tool is to follow particle trajectories in the simulation of magnetic reconnections. The particle trajectory modeling can be used to study particle acceleration processes and examine the transport of particles.
Accomplishments: We have developed a PIC code and a particle trajectory code on Thinking Machines Corp. CM-2 with 32,768 processors. The parallel particle codes have been used to study particle entry into the magnetosphere through the magnetic reconnection region in the polar cusp.
Significance: The developed parallel hybrid PIC codes on massively parallel computers will allow space scientists to model large-scale space phenomena efficiently within a reasonable time. The developed codes will be used to investigate important energy dissipation processes due to ion dynamics during magnetic reconnection.
Status/Plans: Currently, we are developing a 2D hybrid PIC model on the IBM SP-2 computer (160 nodes) at NASA/Ames Research Center. Because the model on the SP-2 will be based on message passing routines, it will differ from the parallel PIC codes on the CM-2. We plan to demonstrate that plasma simulation modeling on massively parallel computers is feasible for performing large-scale calculations for space physics.
Point of Contact:
Dr. Chin S. Lin
Aurora Science Inc.
210-735-7640