GLOWCODE: a one-dimensional code for the simulation of plasma afterglows

GLOWCODE is a one-dimensional cylindrical code which simulates the decay of a hydrogen plasma in which the dominant loss mechanism is three body collisional-radiative recombination. In addition the processes of ionization, radiation, diffusion, heat conduction and equipartition are described. Optically thin conditions are assumed; the limiting case of complete opacity can be studied with the appropriate choice of atomic coefficients. The afterglow is described by the variables, the electron density, the ion density, the atom density, electron temperature, ion temperature and atom temperature. The cylindrical volume is divided into a system of concentric shells and the computation proceeds by solving the various collisional-radiative processes taking place within each shell, and by computing the energy transfer across each shell to its neighbour. At each stage of the calculation pressure balance is re-established by adjusting the cylindrical shells, changing the plasma parameters adiabatically, until the pressure gradient is zero across the plasma radius. Implicit numerical schemes are used for the solution of the conduction and diffusion equations so that there is no stability restriction on the time step for the spatially dependent equations. (Auth.)