France Funds Compact Power Source for Naval Railgun Project

Supercapacitors and an XRAM generator

The agency says the film capacitors that supply this current today are far too large for a frigate. Commercial lithium-ion batteries that were tested hit current limits and took up three times too much space.

The demonstrator will combine supercapacitors, which store energy and release it much faster than a battery, with an XRAM generator, a coil-based circuit that multiplies current during discharge. Hemeria supplies the supercapacitors and will develop their management system, including the charger, test-control software and safety and control hardware. ISL provides the XRAM generator and will validate the supercapacitors in tests representative of its needs.

The test bench targets a peak current above 50,000 amperes, roughly twenty times less than a full shot requires. The goal is to stay within the limits of qualified switching components and to cut the volume and mass of the power chain by a factor of five to ten compared with film capacitors.

A difficult field

The technology has a troubled record. The US Navy stopped its own programme in 2021 after spending about half a billion dollars (nearly 450 million euros) over fifteen years, citing budget constraints and the difficulty of integrating the weapon into its combat systems.

Heat and pressure at each discharge, which wear out equipment significantly, remain unresolved. Calibre and expected performance in range and speed also limit progress.

Several countries still pursue research. The AID continues to count the United States and China among the main players. Japan signed a cooperation agreement on these weapons with France and Germany in 2024 and has already tested its own gun.