SIMULATION OF NEUTRAL ATOMS AND MOLECULES IN AN INTERNATIONAL THERMONUCLEAR EXPERIMENTAL REACTOR HIGH-PRESSURE (1-TORR) ULTRAHIGH RECYCLINGDIVERTOR

The Monte Carlo code DEGAS was used to investigate the neutral atom an d molecular interactions for a high-pressure (similar to 1-Torr) gaseo us divertor in the International Thermonuclear Experimental Reactor (I TER). Energy is removed from the plasma by radiation while the plasma pressure is balanced predominantly by a high neutral pressure at the e nd of the divertor Plasma parameters were taken from the two-dimension al fluid code PLANET Neutral sources from both ions recycling off the walls and recombination were included. The neutral density peak calcul ated with DEGAS of 3.43 +/- 0.01 x 10(22) m(-3) occurred 4.5 cm from t he divertor channel end, The ion and neutral atom energy fluxes were c alculated to determine the hear load onto the divertor walls. A code w as written to calculate the radiation distribution onto the side walls , not including any radiative absorption or reemission. The total ener gy flux peak (including ions, neutrals, and radiation) was 4.28 +/- 0. 30 MW/m(2). This falls below the design criteria of 5 MW/m(2). These r esults may help determine the wall material, heat removal, and the vac uum pumping requirements for the ITER divertor design and show the imp ortance of a full treatment of neutral atoms and molecules in these re gimes.