Parameter Space Constraints for Compact Spherical Tokamak Fusion Reactors

Abstract

Parameter space for spherical tokamak reactors is explored quantitatively to elucidate the main constraints for spherical tokamak design choices. Using a constant plasma current I_p search constraint, a set of four I_p scenarios (5, 10, 15, and 20 MA) is first explored in a wide parameter space. Considering modest but gradually increasing auxiliary power, a set of four machine configurations (major radius $\mathit{R}$ = 1.25, 1.75, 2.25, and 3.5 m) is explored next, optimizing the I_p and the bootstrap fraction. Constraints that narrow down the vast parameter space are elaborated along with critical assumptions, such as current drive efficiency, H-mode enhancement factor, nuclear shielding efficiency, and confinement scaling. Limits on the current density of the center post and how it affects the shielding are quantitatively indicated, thereby setting a lower limit on the aspect ratio.

Keywords:

• Fusion power plant
• spherical tokamak
• reactor design
• systems code
• scoping studies

Acknowledgments

The authors would like to acknowledge the help rendered during the preparation of the manuscript by Research Scholar Piyush Prajapati. We also thank the IPR HPC (ANTYA) team for their help. The authors also would like to acknowledge the anonymous reviewers for their valuable suggestions for improving the quality of the paper.

Disclosure Statement

No potential conflict of interest was reported by the authors.