Numerical Simulation of the Neutralized α Particle Transport near the Divertor Plate Region

The statistical random sample technique has been utilized to develop a new Monte-Carlo algorithm MCHET code recently. A large amount of comparative simulation calculation work relating to the neutralized alpha-particle transport has been performed. As a result, we have found the beneficial optimizing divertor region plasma density and temperature profiles, with the great resulting improvement of helium ash removal efficiency by the simultaneously externally applied proper RF ponderomotive force potential energy in the vicinity of the divertor plate region. In this work the dominant atomic processes of electron impact ionization and elastic scattering by plasma ions are included. The thermal and streaming motion of the ions along the magnetic field is taken into consideration. Important conclusions are obtained that the probability of neutral helium turning back to the target plate will increase at least by 50% for the optimized combination of the beneficial density, temperature profiles and proper RF perpendicular electric field. For FEB (Fusion Experimental Breeder)reactor design parameters, the RF poderomotive potential enhancement from 0.5 to 0.9 of ash removal efficiency can be obviously obtained. In the meantime, the tritium inventory may also be reduced to some extent.