The prospects of creating positron-electron plasmas confined in a stellarator are discussed. A pure electron plasma would be created before the positrons are introduced, to facilitate efficient injection and a long confinement time of the positrons. Gyrokinetic simulations are presented suggesting that a positronelectron plasma may be stable to low-frequency microturbulence if operated well below the Brillouin limit, and transport may be neoclassical. If this is the case, significant positron-electron plasma densities can be reached with positron sources that exist today.

The creation of the first small-Debye length, low temperature pure electron plasmas in a stellarator is reported. A confinement time of 20 ms has been measured. The long confinement time implies the existence of macroscopically stable equilibria and that the single particle orbits are well confined despite the lack of quasisymmetry in the device, the Columbia non-neutral torus. This confirms the beneficial confinement effects of strong electric fields and the resulting rapid E x B rotation of the electrons. The particle confinement time is presently limited by the presence of bulk insulating materials in the plasma, rather than any intrinsic plasma transport processes. A nearly flat temperature profile is seen in the inner part of the plasma.

An experimental demonstration of a compact stellarator magnetic trap created from four circular coils is presented. The coil manufacturing and assembly tolerances were on the order of 0.5-1%, far less stringent than most other stellarators. The simplicity, loose mechanical tolerances, and low cost of the trap design makes it feasible for stellarators to be used for a variety of novel physics experiments, in addition to their present use for magnetic confinement fusion. The experiment, the Columbia Non-neutral Torus, has several other desirable features such as no significant internal island chains and the lowest aspect ratio, A ഛ 1.9, of any stellarator built to date.