Neutral Beam Line Improvements Resulting from a Reduction of Gas Flow

A D+ ion source with a gas utilization efficiency of 85% or greater is feasible and leads to dramatic performance improvements and simplifications of a high energy neutral beam line for fusion reactors. The source should be long compared to present sources and have magnetic multipole boundaries sufficiently intense to be highly reflecting for both ions and electrons. The benefits to be anticipated include the elimination of power dissipation at the acceleration electrodes, removal of the source from direct neutron bombardment, a great reduction in required pumping, and the elimination of reionization losses.