Hollow cathode glow discharge in long tubes

An analysis is made of some burning characteristics of a hollow-cathode glo w discharge with a long tube (L much greater than D) used as the cathode. I t is shown that, as in the case L similar to D, the main factor imposing a lower limit on the range of operating voltages is the drift of fast electro ns through the aperture in the cavity. Assuming that the electrons move alo ng the cavity as a result of diffusion, it was possible to calculate the cr itical pressure at which the discharge can no longer burn and to determine the optimum ratio L/D for which the discharge can be sustained at the lowes t voltage. The calculations showed satisfactory agreement with the experime nt. (C) 1999 American Institute of Physics. [S1063-7842(99)00606-6].