Radiative Heat Transport through Vapor Plasma for Fusion Heat Flux Studies and Electrothermal Plasma Sources Applications

Abstract

High heat fluxes of up to 100 GW/m 2 and greater over a discharge period of 100 to 1000 µs can be generated from electrothermal (ET) plasma sources from the confined arc discharge. Sources with input energy of 10 kJ in a miniature capillary (4 mm radius and 9 cm length) are capable of producing 88.33 GW/m 2 heat flux inside the capillary, higher heat fluxes can be generated for higher input energies. Such high heat fluxes are adequate to simulate the energy deposition during hard disruptions in future fusion tokamak reactors, which result in erosion and thermal deformation of the surfaces of the critical internal components of the reactor. Calculation of the eroded mass due to intensive transient radiative heat transport to the surfaces is very critical in terms of the determination of the performance, durability and the life time of these components. Short intense high heat flux causes surface melting and vaporization. The vapor boundary layer absorbs a fraction of the incident heat flux which results in reducing the overall erosion. The transmitted fraction has a strong dependence on the energy input to the electrothermal source, which is used as a simulator for high heat flux deposition of plasma facing materials. The ETFLOW code models the plasma formation and calculates the plasma parameters for corresponding values of the transmission factor. Comparing experimental measurements to the computationally calculated mass erosion of the ET source material has verified the partial deposition of the incident heat flux. The energy transmission factor through the vapor boundary layer is found to be between 20% -60% for discharge current above 30 kA and between 60% -80% for less than 30 kA. The time of peak discharge current is set to be the time at which the transmission factor is evaluated.applications of such sources as mass accelerators, space minithrusters, propulsions and as high heat flux sources [1][2][3][4]. The heat fluxes generated in electrothermal sources can vary from as low as 5 GW/m 2 to as high as 100 GW/m 2 and greater, making such devices excellent simulators to study high heat flux erosion of plasma-facing components in fusion tokamak reactors [4,5].