Direct conversion of plasma energy to electricity for mirror fusion reactors

Direct conversion of plasma and ion beam energy to electricity for mirror fusion reactors is described. Selective leakage, magnetic expansion, electron separation, deceleration, and collection of ions are discussed. An experiment testing all processes except selective leakage gave an overall efficiency of 86.5 + or - 1.5% for a 22-stage collector. Computer calculations of these same processes gave an efficiency of 88.6 + or - 1.5%, agree. Experiments on a two-stage collector gave 65% efficiency compared to 69% calculated efficiency. One- two-, and 22-stage converters were studied under reactor-like conditions with a large computer simulation code that accounts for space charge, secondary electrons, and finite, realistic electrode shapes. Laboratory tests of mono-energetic beam direct conversion gave 96% efficiency for a 2-keV low power dc beam and 70% for a dc 20 keV, 1-kW beam.