Structure of direct-current microdischarge plasmas in helium

A one-dimensional, self-consistent, continuum model is used to elucidate plasma phenomena in a parallel-plate dc microdischarge with a 250 mum gap at a pressure of 250 Torr. The microdischarge is found to have a bulk plasma region and a cathode sheath region with sizes that are comparable. Depending on the discharge current densities, peak electron densities of order up to 10(14) cm(-3) are predicted. Electron temperature of several eV are predicted within the cathode sheath while temperatures between 2 and 3 eV are observed in the bulk plasma. Gas temperatures of the order of 1000 K are predicted, emphasizing the importance of gas heating phenomena in dc microdischarges. (C) 2003 American Institute of Physics.