Design and Performance of a Linear Flux Pump for the Frascati Coil Cold Test Facility

Abstract

The state-of-the-art power supplies for superconducting magnets are bulky, expensive, and subjected to hundreds of kilowatts of power losses during operation producing significant reactive power absorption and harmonic distortion on the power grid. Moreover, current is injected from room temperature to 4 K coils through current leads, which represent a major source of heat load for the cooling system. Flux pumps are contactless, compact power supply systems able to operate superconducting magnets in a nearly persistent current mode with practically negligible operation losses. Although several small-scale experimental tests already proved the concept of flux pumps, no demonstrators suiting the current and voltage rating of fusion magnets have been built, nor a proper design has been developed. In this study, we developed an application-oriented modelling framework for optimized design of linear flux pumps. This paper presents the framework and a design of a linear flux pump demonstrator with a current capability of 2000 A to be integrated into the Frascati Coil Cold Test Facility. Simulations reporting its performance when employed for the energization of a toroidal field coil of the Divertor Tokamak Test (DTT) are described, both for the ramp up and current maintenance regimes, and its efficient modularity exploitation is analyzed.