Polywell Revisited

TL;DR

This paper revisits the Polywell fusion concept, updating its physics model with recent experimental and simulation data, and outlines a plausible path toward achieving net energy gain with D-T fuels.

Contribution

It provides an improved physics model of the Polywell system incorporating recent findings, addressing previous confinement challenges, and demonstrating potential for net energy gain.

Findings

Updated physics model based on experimental data and simulations

Identification of pathways to overcome confinement losses

Renewed scientific basis for Polywell as a practical fusion approach

Abstract

The Polywell fusion concept, originally proposed by Robert W. Bussard in 1985, has been investigated for over four decades as a potential solution for achieving net fusion energy in a compact and economically viable reactor. It combines two distinct approaches: high-beta magnetic cusp confinement of electrons using polyhedral coil configurations and electrostatic ion confinement via a potential well formed by injected electron beams. While the hybrid nature of the Polywell system offers advantages in plasma stability and engineering simplicity, previous efforts have been limited by persistent challenges in achieving sufficient plasma confinement required to generate a net energy gain. In this study, we examine previous work and identify limitations of several Polywell embodiments that have historically impeded progress. We present an updated Polywell physics model incorporating experimental findings and recent first-principles particle-in-cell simulations. This updated model outlines a credible path toward overcoming confinement losses and achieving net energy gain using deuterium-tritium (D-T) fuels. Our findings provide a renewed scientific basis for the continued development of the Polywell fusion concept as a practical and scalable approach to fusion energy.