# Development of fuel cell power technology for charging high-temperature superconducting coil: Effect of variable resistor

## TL;DR

This paper explores using fuel cells with variable resistors to efficiently charge superconducting coils and control magnetic flux.

## Contribution

A modified variable resistor and controlled gas flow improve fuel cell efficiency for superconducting coil charging.

## Key findings

- Current and magnetic flux density vary with the variable resistor adjustments.
- Controlling gas flow rate increases the current charged to the superconducting coil.
- Fuel cell performance aligns closely with superconducting coil operation data.

## Abstract

This study focuses on developing fuel cell power technology for charging superconducting coils using variable resistor. For this purpose, a variable resistor is fabricated, and experimental equipment is built to control the amount of current applied to the superconducting coil by fixing the amount of gas supplied to the fuel cell and adjusting its driving voltage. The current and magnetic flux densities increase and decrease depending on the variable resistor. A variable resistor is modified by considering the characteristic curve of the fuel cell, and the flow rate supplied to the unit cell is controlled to overcome inefficient energy use. The amount of current charged to the superconducting coil increases depending on the supplied flow rate. Therefore, the measured magnetic flux density increases according to the charged current. Consequently, the fuel cell characteristic evaluation results and data measured while driving the superconducting coil are almost identical.