Confinement performance predictions for a high field axisymmetric tandem mirror

TL;DR

This paper introduces a new model and optimization approach for high field axisymmetric tandem mirror fusion devices, demonstrating the potential for a viable fusion pilot plant with improved design parameters.

Contribution

It presents a novel integrated end plug simulation model combined with machine learning optimization for tandem mirror design, enabling more conservative and feasible fusion pilot plant configurations.

Findings

High fusion gain (Q > 5) achievable with advanced end plug technology.

More conservative operating points with lower temperatures and neutral beam energies.

Detailed end plug modeling highlights importance of radial transport and beam absorption.

Abstract

This paper presents Hammir tandem mirror confinement performance analysis based on Realta Fusion's first-of-a-kind model for axisymmetric magnetic mirror fusion performance. This model uses an integrated end plug simulation model including, heating, equilibrium, and transport combined with a new formulation of the plasma operation contours (POPCONs) technique for the tandem mirror central cell. Using this model in concert with machine learning optimization techniques, it is shown that an end plug utilizing high temperature superconducting magnets and modern neutral beams enables a classical tandem mirror pilot plant producing a fusion gain Q > 5. The approach here represents an important advance in tandem mirror design. The high fidelity end plug model enables calculations of heating and transport in the highly non-Maxwellian end plug to be made more accurately. The detailed end plug modelling performed in this work has highlighted the importance of classical radial transport and neutral beam absorption efficiency on end plug viability. The central cell POPCON technique allows consideration of a wide range of parameters in the relatively simple near-Maxwellian central cell, facilitating the selection of more optimal central cell plasmas. These advances make it possible to find more conservative classical tandem mirror fusion pilot plant operating points with lower temperatures, neutral beam energies, and end plug performance requirements than designs in the literature. Despite being more conservative, it is shown that these operating points have sufficient confinement performance to serve as the basis of a viable fusion pilot plant provided that they can be stabilized against MHD and trapped particle modes.