Real-time measurements of quartz erosion in experiments modeling heat loads on divertor plates during disruption in tokamaks

Time-resolved measurements of quartz erosion are carried out to determine t he density of the energy flux incident onto the sample surface. These data are needed to create a reliable code describing the interaction of a thermo nuclear plasma with a solid surface. Experiments were performed in the 2MK- 200 facility under the program of modeling heat loads on divertor plates du ring disruptions in tokamaks. A 10-mm-thick plate of fused quartz was expos ed to a high-temperature deuterium-plasma stream with the temperature T-i T-e less than or equal to 1 keV, density (5-10) x 10(15) cm(-3), beta = 0. 25, energy density up to 200 J/cm(2), and power density similar to 10 MW/cm (2). It is shown that the quartz erosion begins almost immediately after th e stream reaches the surface. The eroded material shields the quartz surfac e from further destruction. Under the given experimental conditions, the in tegral shielding factor (the ratio of the stream energy to the energy reach ing the surface) was rather high (about seventeen). As a result, at a strea m energy density of similar to 150 J/cm(2), the total erosion depth was abo ut 0.75 mum over 35 mus. Based on the measured time dependence of the erosi on depth and the reference data on the thennal conductivity of the fused qu artz, the power density incident onto the quartz sample was numerically cal culated. (C) 2001 MAIK " Nauka/Interperiodica ".