Improved Confinement in Inertial Electrostatic Confinement for Fusion Space Power Reactors

Abstract

Multiple improvements to the inertial-electrostatic-confinement (IEC) fusion concept are presented. Prior efforts have consisted of considerable theoretical effort and numerous ground experiments resulting in the fusion of D-D, D-T, and D- 3 He at rates on the order of 10 1 0 reactions per second. Theory developed in the paper shows that prior experiments, which observed a linear relationship between reaction rate and background pressure, were limited. With improved ion confinement, the reaction rate and the pressure should decouple at high pressure where the beam-beam reactions are not yet dominant. Highly efficient beam-beam reaction rates are found to dominate the total reaction rate as ion lifetime is increased. The ion lifetime is limited mainly by collisions with background particles and by defocusing. The naturally low background pressure available in the space environment effectively eliminates background pressure as a constraint on ion lifetime, leaving defocusing as the main ion lifetime limiter. To improve ion confinement, multiple grids are introduced to produce focusing channels for ions. The other main loss mechanism is electrons streaming from the core region to the anode. An additional grid is placed within the cathode, providing a central trap for core electrons. Theory predicts that improvements in confinement should be verifiable using existing relatively high-pressure ground systems and the proposed experiment design is presented. The buildup of space charge in the focusing lenses is used to estimate improvements in confinement from < 10 passes to the order of 1000 passes, boosting the performance of IEC reactors by two orders of magnitude, yielding in the near term, a fast neutron source suitable for medical, security, research, and industrial applications. Further increases of confinement will enable net power production in reactors ideally suited for spacecraft power production as a result of low system mass in comparison to magnetic confinement fusion.