Over the past few years I’ve posted several times about the Polywell fusion power concept invented by the late Robert W. Bussard. See, for example, this introductory video on the Polywell fusion system.
The Navy funded project investigating the system has been very quiet for the past year or so and I’ve not seen any new info on how they were doing. Today, however, comes word of a technical paper posted at arXiv.org and it sounds quite encouraging:
We report experimental results validating the concept that plasma confinement is enhanced in a magnetic cusp configuration when beta (plasma pressure/magnetic field pressure) is order of unity. This enhancement is required for a fusion power reactor based on cusp confinement to be feasible.
The magnetic cusp configuration possesses a critical advantage: the plasma is stable to large scale perturbations. However, early work indicated that plasma loss rates in a reactor based on a cusp configuration were too large for net power production. Grad and others theorized that at high beta a sharp boundary would form between the plasma and the magnetic field, leading to substantially smaller loss rates.
The current experiment validates this theoretical conjecture for the first time and represents critical progress toward the Polywell fusion concept which combines a high beta cusp configuration with an electrostatic fusion for a compact, economical, power-producing nuclear fusion reactor.