TPX divertor design: neutral atom behavior and optimization for pumping

The particle throughput of TPX must be greater than 85 Torr-l/s to ensure the capability of steady-state operation. This throughput must be maintained by active pumping and clever design of the divertor components. In this paper seven geometrical variations of the divertor structures are modeled using the B2 edge-plasma fluid code and DEGAS Monte-Carlo neutral transport code. Results show that eliminating the gap between the inner divertor plate and the baffle, and reducing the gap between the outer divertor plate and the baffle by two-thirds will improve the particle throughput over the reference design by a factor of four. The resulting throughput from this new geometry is 91.8/spl plusmn/10.9 Torr-l/s.