Radiative pulsed L-mode operation in ARC-class reactors

TL;DR

This paper proposes a novel pulsed, radiative L-mode plasma scenario for ARC-class tokamaks that achieves high fusion power density and core radiation fractions, reducing divertor heat loads and avoiding steady-state constraints.

Contribution

It introduces a high-field, pulsed L-mode operation with high core radiation, validated through integrated simulations, as an alternative to steady-state tokamak designs.

Findings

Achieves >1000 MW fusion power in compact devices

Maintains high core radiation fractions (~90%) in L-mode

Demonstrates feasibility through self-consistent simulations

Abstract

A new ARC-class, highly-radiative, pulsed, L-mode, burning plasma scenario is developed and evaluated as a candidate for future tokamak reactors. Pulsed inductive operation alleviates the stringent current drive requirements of steady-state reactors, and operation in L-mode affords ELM-free access to $\sim90\%$ core radiation fractions, significantly reducing the divertor power handling requirements. In this configuration the fusion power density can be maximized despite L-mode confinement by utilizing high-field to increase plasma densities and current. This allows us to obtain high gain in robust scenarios in compact devices with $P_\mathrm{fus} > 1000\,$MW despite low confinement. We demonstrate the feasibility of such scenarios here; first by showing that they avoid violating 0-D tokamak limits, and then by performing self-consistent integrated simulations of flattop operation including neoclassical and turbulent transport, magnetic equilibrium, and RF current drive models. Finally we examine the potential effect of introducing negative triangularity with a 0-D model. Our results show high-field radiative pulsed L-mode scenarios are a promising alternative to the typical steady state advanced tokamak scenarios which have dominated tokamak reactor development.