Test of divertor materials under simulated ITER plasma disruption conditions at the GOL-3 facility

The GOL-3 facility was used for exploratory plasma stream target experiments under conditions rather typical for the thermal quench phase of ITER tokamak plasma disruptions. The experiments allowed study of the properties of target plasmas formed from vaporized target materials in front of the target and determination of the target material erosion. Within 2 μs after the onset of the plasma stream a cloud of evaporated material is formed. The cloud expands along magnetic force lines with velocities around 106 cm/s. Line radiation is observed from the target plasma corona, continuum radiation from the bulk of the cloud. The temperature in the plasma corona is about 1 eV. The black body temperature of the bulk cloud is below 0.5 eV. The erosion for graphite increases sharply upon reaching a threshold value of 1 MJ/m2 for the energy density of the hot plasma stream and achieves very high values. ((orig.))