Mixed Deuterium-Tritium Neutral Beam Injection: An Alternative Heating Method for Fusion Reactors

An alternative mixed beam neutral beam injector (MNBI) for fusion reactors is proposed that eliminates the conventional isotope separation system (ISS) in the fuel cycle. The principal advantage of the alternative system is a capital and operating cost savings in the fuel cycle, as the ISS employs cryogenic distillation at liquid-hydrogen temperatures to effect a separation of hydrogen isotopes and to eliminate a buildup of normal hydrogen in the recycled fuel. Possible additional advantages of the alternative method involve an improvement in overall safety and a reduction of the amount of tritium in the fuel cycle. The alternative heating system uses an electromagnetic separation in the MNBI to limit the buildup of normal hydrogen. Calculations indicate that an MNBI can be reasonably optimized in the case of an upgraded injection system for the Tokamak Fusion Test Reactor.