Development of an axisymmetric mirror-based neutron source using recent advances in technology*

We report an overview of work at the University of Wisconsin leading to a fusion neutron source based on axisymmetric mirrors, following along the Gas Dynamic Trap line of development.  The design considers several recent physics and technological advances and uses off-the-shelf MRI magnets for an inexpensive central cell, state-of-the-art planar high field REBCO magnets and gyrotrons to allow high density operation.  Improved performance is realized from sloshing ions (to localize neutron yield away from high field magnets), rf heating at the fast-ion turning points to enhance neutron yield, and a liquid lithium expanding diverter for heat removal, electron thermal barrier and MHD stability. Equilibrium, stability, and plasma heating scenarios have been modeled using a Grad-Shafranov solver for the mirror including fast ion pressure coupled to the CQL3D/Genray suite of codes. We have been considering both paraxial and short-fat MHD optimizations of coil design. MHD stability is assessed using both energy principle calculations and ballooning mode eigenmode analysis. Initial results are very promising, with strong DD neutron yields (~10¹⁵/s) with reasonable input power (40 MW).