HEAT FLOWS THROUGH PLASMA SHEATHS

Plasma heat flow to material surfaces through sheaths is studied, taki ng several key physics factors into account. Electron emission from th e surface, which breaks a thermal insulation of the sheath, is studied in both thermoelectron emission (TEE) and secondary electron emission (SEE), in which a correct expression under space charge limited condi tion is given for arbitrary sheath voltages. Nonlinear thermal bifurca tion induced by electron emission is analyzed in the experiment and th e theory. The local heat flow was found to be enhanced by a thermal co ntraction induced by cross-field potential variation In a plasma. An e nhancement of SEE of hydrogen-absorbed graphite, and a suppression of SEE by the gyromotion of emitted electrons in obliquely incident magne tic field are identified. The effects of ion reflection on the surface and ponderomotive force are also discussed in terms of energy transmi ssion factor delta. An anomaly of delta in detached recombining plasma s is discussed. (C) 1998 American Institute of Physics.