Particle in cell simulations of low pressure small radius positive column discharges

Improved positive column simulation techniques are needed because of the non-local nature of typical low-pressure discharges used for lighting. In a local model. the pow,er balance between Joule heating and collisional losses must hold for each volume element of the discharge separately while a non-local model requires only a global power balance. The departure from locality increases as either gas density n(g) or radius R is decreased. Despite this, most current fluorescent lamp software is based on the local concept, We present a non-local kinetic particle-in-cell Monte Carlo collisions (PIC-MCC) code to simulate low-pressure, small-radius. positive column discharges. This code is also compared to a non-local fluid code. a non-local kinetic Monte Carlo code and to experimental data. The PIC-MCC code made the least approximations and assumptions and was accurate and stable over a wider parameter regime than the other codes. Also. 1d3v PIC-MCC simulation speeds are quite competitive even on moderate workstations. Finally, we analyse the PIC-MCC simulation results in detail, especially the power balance and the radial electron kinetic energy flux H-r (r). We found that for low n(g) R < 1 x 10(15) cm(-2), the electron kinetic energy flux is directed radially outward while for higher n(g) R, it is directed radially inward except right near the wall.