Thick Liquid-Walled Spheromak Magnetic Fusion Power Plant

Abstract

We assume a spheromak configuration can be made and sustained by a steady plasma gun current, which injects particles, current and magnetic field, i.e., helicity injection. The magnetic configuration is evaluated with an axisymmetric free-boundary equilibrium code, where the current profile is tailored to support an average beta of 10%. An injection current of 100 kA (125 MW of gun power) sustains the toroidal current of 40 MA. The flux linking the gun is 1/1000th of the flux in the spheromak. The geometry allows a flow of liquid, either molten salt (flibe-Li{sub 2}BeF{sub 4} or flinabe-LiNaBeF{sub 4}) or liquid metal, such as SnLi, which protects most of the walls and structures from neutron damage. The free surface between the liquid and the burning plasma is heated by bremsstrahlung and optical radiation and neutrons from the plasma. The temperature of the free surface of the liquid is calculated and then the evaporation rate is estimated. The impurity concentration in the burning plasma is estimated and limited to a 20% reduction in the fusion power ({approx}0.8% fluorine impurity). The divertor power density of 620 MW/m{sup 2} is handled by high-speed (100 m/s) liquid jets. Calculations show that the tritium breeding is adequate with enriched {sup 6}Li and appropriate design of the walls not covered by flowing liquid (15% of the total). A number of problem areas need further study to make the design self consistent and workable, including lowering the divertor power density by expanding the flux tube size.