CIT divertor design approach and preliminary concept

Abstract

The Compact Ignition Tokamak (CIT) project is currently in the preliminary design phase. The compact size and high performance nature of CIT leads to heat fluxes of approximately 40 MW/m/sup 2/ on divertor surfaces. To minimize plasma impurities, CIT has established the objective of maintaining plasma-facing components below 1700 degrees C. Divertor design and analysis efforts to date have focused on establishing a feasible design approach which meets CIT objectives for energy removal and remote maintenance while minimizing the total thickness envelope of the divertor module and support structure. A concept which utilizes 400 passively cooled divertor modules, to form the upper and lower divertor plates was developed. Since the peak surface temperature (which determines the impurity release to the plasma) is a key parameter which directly affects the overall performance and viability of the CIT experiment, thermal performance of the divertor was optimized by providing relatively thick (40-mm), high-conductivity pyrolytic graphite tiles as the plasma-facing material and by determining the separatrix sweeping rate that minimizes the peak surface temperature.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>