EFFECTS OF VAPOR SHIELD EXPANSION ON VAPOR SHIELD EFFECTIVENESS AND PLASMA GUN EFFICIENCY

The vapor shield outward expansion rate can be shown to affect energy transport through the vapor shield, thereby influencing the vapor shie ld effectiveness. To more accurately determine the divertor plate eros ion depth from a tokamak fusion reactor disruption or plasma gun sourc es, it is then necessary to include source plasma (beam) momentum tran sfer and beam mass deposition to the expanding vapor shield. Other fac tors such as incident heat flux and target Z value are shown to influe nce the vapor shield expansion rate as well. Code calculations show th at increasing heat fluxes can increase the fraction of vapor shield ki netic energy and lower the fraction f of incident energy transported t o the solid Low-Z materials give higher kinetic energies as well but r esult in a higher f due to a lower specific hear. These results can al so be applied to plasma gun technology to help increase its efficiency . fn an electrothermal gun, the plasma expansion rate (rate at which v aporized material travels out of the gun) can cause differing plasma r esidence times and differing plasma temperatures as well. Determining the mechanisms that influence the vapor shield expansion rate and show ing its sensitivity on f can give us a qualitative way of determining how changing parameters can influence plasma gun efficiency. Low-energ y (<200 eV) disruption plasmas add much mass as well as momentum to a vapor shield, Mass addition can cause the vapor shield temperature and f to differ for a given incident heat flux and change the vapor shiel d expansion rate as well. Also we find that deuterium's shielding effe ctiveness differs from carbon.