Combined sheath and thermal analysis of overheated surfaces in fusion devices

摘要: Abstract The phenomenon of runaway surfaces overheating in fusion experiments due to plasma-sheath/surface-emission coupling has been analyzed. A semi-analytic model used as well the BPHI-3D kinetic sheath code (J.N. Brooks, D. Naujoks, Phys. Plasmas 7 (2000) 2565) coupled with THERM which solves non-stationary heat conduction equation also 3D geometry. Runaway heating initial and subsequent breakdown superheat analyzed for two materials – lithium carbon. For typical liquid divertor conditions critical exposure time thermal is order 10 ms generally greater than plasma transient periods (e.g., ELMS) or flowing times. Critical times carbon are much longer (∼1–2 s), expected property differences, this may explain various `hot spot' formations systems. It shown that, especially materials, effects such flake formation deterioration conductivity can play a crucial role.