DENSITY PROFILE CONTROL IN A FUSION-REACTOR USING PELLET INJECTION

The relationships between plasma parameters that are dependent on the density profile (fusion rate, core and edge densities and temperatures , density and temperature profile peaking), fuel particle pumping in t he divertor (expressed as particle throughput) and pellet injection pa rameters (size, velocity and injection frequency) are examined for tok amak reactor plasmas. These relationships are illustrated with the res ults of transport simulations of steady state conditions for a nominal set of reactor parameters representative of the International Thermon uclear Experimental Reactor (ITER) using pellet parameters characteris tic of both present and advanced injectors. The radial separation betw een the pellet source and the pumping in the divertor region, even wit h very modest pellet velocities, allows for the possibility of density profile control in the plasma edge. When matching both fusion power a nd edge density constraints, fuel particle throughput decreases with i ncreasing pellet penetration. The sensitivity of the results to the de tails of the transport model and to the limit on the edge density is a lso examined.