Nonlinear interactions between high heat flux plasma and electron-emissive hot material surface

Nonlinear dynamic behaviors are investigated for a system composed of high heat flux plasma and electron-emissive hot material surface. Phase transitions due to bifurcation have been observed in the experiments and analyzed numerically by using a series of simple equations describing energy balance as well as sheath formation, including a new Child–Langmuir expression for an electron emission from the material surface into the plasma. It is found that the thermal insulation between these two constituent parts depends not only on plasma parameters but also strongly on electron-emission characteristics of the material surface in a nonlinear way. The electron emission leads to a strong reduction of sheath voltage and a large enhancement of heat flux density on the material surface. The plasma is cooled when it is in contact with a strongly electron-emissive material surface.