TEMHDDriven Liquid Lithium for Neutron Generator Targets

Plasma facing components have significant challenges for fusion reactors and commercial uses of fusion energy, e.g. compact neutron generators. Economical systems have very high power densities with enormous particle flux loadings that exceed capabilities for conventional static materials, e.g. W, Mo, Cu and stainless steels. The proposed solution uses flowing liquid metal layers to transport heat and/or ash away for even higher attainable power densities in these machines. The critical missing piece is obtaining high flow speeds with stability and control in a compact, lightweight form factor. The thermos electric magneto hydrodynamic (TEMHD) effect is an intrinsic property of selfpumping and flow from a J x B force. Beam or plasma loading on one surface will generate a thermal gradient that produces net electron flow in the material that in the presence of a magnetic field will cause bulk motion. The TEMHD effect has been demonstrated using liquid lithium on a largescale experiment at low flow velocities. The objective of this SBIR/STTR program was to investigate the technical feasibility to increase TEMHD velocity to handle higher heat fluxes and particle loadings. Faster material transport will minimize evaporation or contamination on surfaces relevant for fusion. Using an innovative technique, a means to handle higher heat loads in a small form factor could lead to developing alternative technologies to replace radioactive materials used in open industrial use. Size reduction, portability and integrated operation were secondary objectives. All of the Phase I objectives were achieved and technical feasibility was demonstrated in both simulation and experiment. The demonstrated portability of the test fixture (13MeV generated without using tritium with advanced DLi fusion reactions. Very high ion beam currents are needed for intense irradiation in a novel generator setup. A liquid lithium solution that can handle the thermal and particle loading is needed. The demonstrated TEMHD effect offers a potential solution for this need. Commercial Applications and Other Benefits The technology has immediate application for radiochemical replacement. Other benefits are potential for sensor systems for gammaray inspection for explosives, carbon heating value measurement and oxygen ratio estimation. Security inspection and industrial clients in raw materials processing will greatly benefit from the highenergy neutron capability with lower cost and improved safety. A high power version could be used for fusion materials irradiation testing.