3D ELECTROMAGNETIC PLASMA PARTICLE SIMULATIONS ON A MIMD PARALLEL COMPUTER

A three-dimensional electromagnetic PIC code has been developed on the 512 node Intel Touchstone Delta MIMD parallel computer. This code uses a standard relativistic leapfrog scheme to push particles and a local finite-difference time-domain method to update the electromagnetic fields. The code is implemented using the General Concurrent PIC algorithm which uses a domain decomposition to divide the computation among the processors. The 3D simulation domain can be partitioned into 1-, 2-, or 3-dimensional subdomains. Particles must be exchanged between processors as they move among the subdomains, The Intel Delta allows one to use this code for very-large-scale simulations (i.e. over 10(8) particles and 10(6) grid cells). The parallel efficiency of this code is measured, and the overall code performance on the Delta is compared with that on Gray supercomputers. It is shown that our code runs with a high parallel efficiency of greater than or equal to 95% for large size problems. The particle push time achieved is 115 ns/particle/time step for 162 million particles on 512 nodes. Compared with the performance on a single CPU Gray C90, this represents a factor of 58 speedup. It is also shown that the finite-difference method for the field solve is significantly more efficient than transform methods on parallel computers. The field solve time is < 0.7% of total time for problems with 77 particles/cell, and it is < 3% even for problems with 7 particles/cell.