Simulation of a positive column discharge with a one-dimensional radial radiation transport coupled particle-in-cell model

A one-dimensional radial slice of an Ar positive column discharge is simula ted with a radiation transport coupled particle-in-cell model. The discharg e is maintained by an axial current in the positive column which induces a self-consistent axial electric field. Power balance and radiation efficienc y are investigated for variations of axial driving current I-z, gas pressur e p, and radius R. The parameter regimes are from 0.1 to 1 cm for radius, 1 mTorr to 20 Torr for gas pressure, from 4 to 14 eV for electron temperatur e, from 10(15) to 10(17) m(-3) for peak plasma density, and from 0.15 to 50 mA for axial current. The radiation efficiency is related to the product o f the pressure and the radius, pR; it is restricted by the large wall loss for small pR and by the collisional quenching of the radiative state for la rge pR. The optimal value is about pR=1 Torr cm for this parameter regime. (C) 2001 American Institute of Physics.