What Is Explosive Pulsed Power?

Explosive pulsed power is a branch of pulsed power engineering that uses chemical explosives as the primary energy source to generate extremely brief but extremely intense electrical pulses, typically reaching megajoule energy levels and gigawatt peak powers. The technique exploits the high energy density stored in high explosives, which is roughly an order of magnitude greater than that available from capacitor banks of comparable volume, to drive experiments that require energy levels impractical to achieve through conventional electrical storage. The field draws on detonics, plasma physics, electromagnetic theory, and high-voltage engineering, and it has been developed primarily at national laboratories concerned with nuclear weapons effects, electromagnetic pulse research, and high-energy-density physics.

The foundational device in the field is the flux compression generator (FCG), conceived by Andrei Sakharov in the early 1950s to power Soviet fusion experiments. An FCG traps an initial magnetic field inside a conducting cavity and then uses detonating explosive to rapidly compress the cavity. As inductance falls, current and magnetic field intensity rise in inverse proportion, converting chemical energy into electromagnetic energy with efficiencies in the range of 10 to 30 percent. A review of U.S. high explosive pulsed power systems by J.H. Goforth of Los Alamos National Laboratory surveys the two principal generator architectures, helical and coaxial, and documents the opening switch designs used to couple generator output to experimental loads.

Flux Compression Generators

Helical generators, in which a cylindrical explosive charge compresses a helical coil winding, are the most widely used FCG type for high-energy applications. Advanced helical generators can produce peak currents of 20 megaamperes and energies above 20 megajoules in a single shot. Coaxial generators, which compress a cylindrical conducting liner inside an outer coil, produce shorter, higher-peak-current pulses better suited to certain loads. These devices are inherently single-use: the explosive destroys the generator during each experiment, so design for rapid fabrication and reproducibility is central to the engineering effort.

The quality of the initial seed field, usually provided by a capacitor bank or a preceding smaller FCG stage, strongly influences final output. Research from Los Alamos and Lawrence Livermore national laboratories on flux compression diagnostics describes how current probes, magnetic field probes, and velocity interferometry are fielded within the explosion environment to characterize generator performance on sub-microsecond timescales.

Coupling and Load Delivery

Delivering the compressed pulse to a useful load requires opening switches capable of diverting current in nanoseconds against multi-megaampere flows. Explosive opening switches, which interrupt current by using a detonating charge to sever a conductor, are common because their timing can be precisely coordinated with the generator's output peak. The energy coupled to the load drives a range of targets: railguns, plasma focus devices, high-power microwave sources, and high-field magnet experiments. Science.gov's topic aggregation on flux compression generators indexes research across national laboratories and defense contractors on both generator characterization and load coupling, illustrating the breadth of institutional investment in the technology. In military research, FCG-based systems have been studied as potential sources for directed energy weapons and electromagnetic pulse generation.

Applications

Explosive pulsed power has applications in a wide range of disciplines, including:

• High-energy-density physics experiments at national laboratories
• Electromagnetic pulse simulation for hardening electronic systems
• High-power microwave source development for directed energy research
• High-field magnet and plasma physics research
• Rail gun and coilgun propulsion system testing