High Energy Electron Confinement in a Magnetic Cusp Configuration

TL;DR

This paper experimentally confirms that plasma confinement improves significantly in a magnetic cusp configuration at high beta, supporting the feasibility of cusp-based fusion reactors with enhanced stability and reduced plasma loss.

Contribution

First experimental validation of high beta plasma boundary formation in a magnetic cusp, advancing the Polywell fusion concept.

Findings

Enhanced plasma confinement at high beta

Stable plasma boundary formation observed

Progress toward practical cusp-based fusion reactor

Abstract

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.