Magnetic electrostatic plasma confinement

Electrostatic plasma confinement and magnetic electrostatic plasma confinement (MEPC) have been studied for four decades. The multiple potential well hypothesis, postulated to explain high neutron yields from Hirsch's colliding beam experiment (1968), has been supported by several pieces of evidence, but results were inconclusive. Magnetic shielding of the grid was developed to reduce the required beam current and to prevent grid overheating. Electrostatic plugging of magnetic cusps evolved to a similar configuration. Due to low budgets, early MEPC experiments used spindle cusps, which are poor for plasma confinement. Later experiments used multipole cusps or a linear set of ring cusps, which have larger volumes of field-free plasma. To keep the self-shielding voltage drop Delta phi <or=100 kV, the electron density na in the anode gap should be less than about 1019 m-3. The central plasma density can be an order of magnitude higher. The ATOLL toroidal quadrupole had anomalous electron energy transport, but the Jupiter-2M linear set of ring cusps achieved a transport rate about a factor of two above the classical rate. With near-classical transport, a power gain ratio Q approximately=10 is predicted for a reactor with rp=3m, Ba=6T, and applied voltage phi A=400 kV. Besides producing electricity and synthetic fuels, MEPC reactors could be used for heavy ion beams sources and neutron generators. The main issues of concern for MEPC reactor development are electron transport, plasma purity and electrode alignment and voltage holding.