The York Research Database

The rates of atomic processes in cold, dense plasmas are governed strongly
by effects of quantum degeneracy. The electrons follow Fermi-Dirac statis-
tics and their high density limits the number of quantum states available
for occupation after a collision. These factors preclude a direct solution to
the usual rate coefficient integrals. We summarise the formulation of this
problem and present a simple, but efficient method of evaluating collisional
rate coefficients via direct numerical integration. Numerical quadrature has
an intrinsically high level of parallelism, ideally suited for graphics processor
units. GPUs are particularly suited to this problem because of the large
number of integrals which must be carried out simultaneously for a given
atomic model. A CUDA code to calculate the rates of signicant atomic
processes as part of a collisional-radiative model is presented and discussed.
This approach may be readily extended to other applications where rapid
and repeated evaluation of many integrals is required.