Modelling of the vapor shield mechanism during high heat flux ablation of surfaces

Summary form only given, as follows. The ablation process occurring at material surfaces in electromagnetic launchers, electrothermal guns, etc., which has a profound impact on device performance in the areas of projectile drag, conversion efficiency, and component lifetime, has been studied. The vapor shield mechanism that develops to form the ablation plasma boundary layer under these conditions has been modeled. Of critical importance is the fraction f of energy transmitted through the vapor shield during the exposure time. One-dimensional, time-dependent, MHD calculations (MAGFIRE code) have been performed in conjunction with the photon radiation transport to predict f. A global, time-dependent code ZEUS then solved particle and energy balance equations for the purpose of comparison with actual ablation measurements. The ZEUS code simulates the plasma conditions in the electrothermal gun breech region. A formal solution for the radiative transfer equation has been derived, and the results have been compared with the results using the diffusion approximation.<>