Incorporating line radiation effects into edge plasma codes

Strong hydrogen line radiation can significantly affect the ionization and energy balance in high-density, low-temperature edge plasmas. A fully self-consistent one-dimensional simulation code integrating line radiation with edge plasma transport has recently been demonstrated. This code allows us to evaluate the use of approximate treatments of radiation effects that could potentially be incorporated into existing two-dimensional edge plasma codes. For a given approximation, we tabulate effective ionization, recombination and energy loss rates for hydrogen plasmas in a one-dimensional geometry as a function of electron density, temperature and position. The position is a simple parameterization corresponding to optical depth, with the correspondence dependent on plasma properties, including magnetic field. The parameterized values can differ by more than an order of magnitude from the optically thin values. We present one-dimensional edge plasma simulations using the parameterized tables and compare them to self-consistent simulations to investigate the validity of this approach, the effectiveness of the parameterization and the accuracy of the approximations used. We also present results using parameterized tables in a two-dimensional code and discuss the validity of applying them in this manner.