Ideal Magnetohydrodynamic Simulations of Low Beta Compact Toroid Injection into a Hot Strongly Magnetized Plasma

TL;DR

This paper uses 3D ideal MHD simulations to study low beta compact toroid injection into a hot magnetized plasma, identifying regimes for effective core fueling and analyzing the evolution stages.

Contribution

It provides new insights into optimal injection parameters and the dynamic stages of CT penetration relevant for tokamak fueling in ITER conditions.

Findings

Penetration depth scales with injection speed and density.

Identified regimes suitable for precise core fueling.

Shock-dominated regimes are likely unfavorable for fueling.

Abstract

We present results from three-dimensional ideal magnetohydrodynamic simulations of low $\beta$ compact toroid (CT) injection into a hot strongly magnetized plasma, with the aim of providing insight into CT fueling of a tokamak with parameters relevant for ITER (International Thermonuclear Experimental Reactor). A regime is identified in terms of CT injection speed and CT-to-background magnetic field ratio that appears promising for precise core fueling. Shock-dominated regimes, which are probably unfavorable for tokamak fueling, are also identified. The CT penetration depth is proportional to the CT injection speed and density. The entire CT evolution can be divided into three stages: (1) initial penetration, (2) compression in the direction of propagation, and reconnection with the background magnetic field, and (3) coming to rest and spreading in the direction perpendicular to injection. Tilting of the CT is not observed due to the fast transit time of the CT across the background plasma.