A Lithium Vapor-Box Divertor for Tokamak Applications

Abstract

This thesis begins research into a novel “vapor box” design for a tokamak divertor, intended to enable greater heat and particle capture than current solid plate designs. It consists of a box filled with lithium vapor, later adapted to a chain of five vapor-filled boxes with length and width 0.4m connected by slots of width 0.1m. These boxes are situated along a fixed temperature gradient and their walls are covered with capillary-porous material containing liquid lithium. Consider the plasma entering the box as a “sheet” absorbing energy and particles and re-emitting them into the lithium vapor in the hottest box. The slots between the boxes serve as effective vapor pumps from box to box. Calculations of density, vapor temperature, and mass and power flow from box to box are made. It is discovered that the mass and power effluxes back into the main plasma chamber are modest. In addition, these vapor densities appear sufficient to stop particles of up to 20 keV. Theoretical investigation is also in progress with respect to understanding plasma-vapor interactions and plasma dynamics within the sheet itself. Future work includes solutions to the differential equations governing plasma motion in this system and 2D modeling of the vapor box, as well as benchmark physical experiments on an actual vapor box and eventual testing on a tokamak.