A relatively common variant of this configuration is the augmented railgun in which the driving current is channeled through additional pairs of parallel conductors, arranged to increase ('augment') the magnetic field experienced by the moving armature.

[12][16] By late 1944, the theory behind his electric anti-aircraft gun had been worked out sufficiently to allow the Luftwaffe's Flak Command to issue a specification, which demanded a muzzle velocity of 2,000 m/s (4,500 mph; 7,200 km/h; 6,600 ft/s) and a projectile containing 0.5 kg (1.1 lb) of explosive.

The work was conducted predominantly at the Aberdeen Proving Ground, and much of the early research drew inspiration from the railgun experiments performed by the Australian National University.

[24] While military research into railgun technology in the United States ensued continuously in the following decades, the direction and focus that it took shifted dramatically with major changes in funding levels and the needs of different government agencies.

In 1984, the formation of the Strategic Defense Initiative Organization caused research goals to shift toward establishing a constellation of satellites to intercept intercontinental ballistic missiles.

As a result, the U.S. military focused on developing small guided projectiles that could withstand the high-G launch from ultra-high velocity plasma armature railguns.

But after the publication of an important Defense Science Board study in 1985, the U.S. Army, Marine Corps, and DARPA were assigned to develop anti-armor, electromagnetic launch technologies for mobile ground combat vehicles.

[25] In 1990, the U.S. Army collaborated with the University of Texas at Austin to establish the Institute for Advanced Technology (IAT), which focused on research involving solid and hybrid armatures, rail-armature interactions, and electromagnetic launcher materials.

[30][31] In 2010, the United States Navy tested a BAE Systems-designed compact-sized railgun for ship emplacement that accelerated a 3.2 kg (7 pound) projectile to hypersonic velocities of approximately 3,390 m/s (7,600 mph; 12,200 km/h; 11,100 ft/s), or about Mach 10, with 18.4 MJ of kinetic energy.

[36] This current makes the railgun behave as an electromagnet, creating a magnetic field inside the loop formed by the length of the rails up to the position of the armature.

A very large power supply, providing on the order of one million amperes of current, will create a tremendous force on the projectile, accelerating it to a speed of many kilometers per second (km/s).

At this time it is generally acknowledged that it will take major breakthroughs in materials science and related disciplines to produce high-powered railguns capable of firing more than a few shots from a single set of rails.

Currently different rail shapes and railgun configurations are being tested, most notably by the U.S. Navy (Naval Research Laboratory), the Institute for Advanced Technology at the University of Texas at Austin, and BAE Systems.

This causes three main problems: melting of equipment, decreased safety of personnel, and detection by enemy forces owing to increased infrared signature.

The weapon launches a streamlined discarding sabot round designed by Boeing's Phantom Works at 1,600 m/s (5,200 ft/s) (approximately Mach 5) with accelerations exceeding 60,000 gn.

MARAUDER (Magnetically Accelerated Ring to Achieve Ultra-high Directed Energy and Radiation) is, or was, a United States Air Force Research Laboratory project concerning the development of a coaxial plasma railgun.

[citation needed] Full-scale models have been built and fired, including a 90 mm (3.5 in) bore, 9 megajoule kinetic energy gun developed by the US DARPA.

[77] At the University of Texas at Austin Center for Electromechanics, military railguns capable of delivering tungsten armor-piercing bullets with kinetic energies of nine megajoules (9 MJ) have been developed.

[78] Nine megajoules is enough energy to deliver 2 kg (4.4 lb) of projectile at 3 km/s (1.9 mi/s)—at that velocity, a sufficiently long rod of tungsten or another dense metal could easily penetrate a tank, and potentially pass through it, (see APFSDS).

The main problem the U.S. Navy has had with implementing a railgun cannon system is that the guns wear out because of the immense pressures, stresses and heat that are generated by the millions of amperes of current necessary to fire projectiles with megajoules of energy.

One shot would require 6 million amps of current, so it will take a long time to develop capacitors that can generate enough energy and strong enough gun materials.

[76] The most promising near-term application for weapons-rated railguns and electromagnetic guns, in general, is probably aboard naval ships with sufficient spare electrical generating capacity and battery storage space.

In July 2017, Defensetech reported that the Navy wished to push the Office of Naval Research's prototype railgun from a science experiment into useful weapon territory.

[106] In 1991, they determined the properties required for developing an effective launch package as well as the design criteria necessary for a railgun to incorporate finned, long rod projectiles.

The facility also provided a power system that included thirteen 1- MJ capacitor banks, an assortment of electromagnetic launcher devices and diagnostic apparatuses.

[111] In 1999, a collaboration between ARL and IAT led to the development of a radiometric method of measuring the temperature distribution of railgun armatures during a pulsed electrical discharge without disturbing the magnetic field.

[114] Early papers describe the plasma-propellant interaction group at ARL and their attempts to understand and distinguish between the chemical, thermal, and radiation effect of plasmas on conventional solid propellants.

[124] The Japanese Ministry of Defense started its survey on railgun-related technology domestically and internationally by 2015, while conducting basic research using a small caliber railgun with a 16mm bore.

[126] From FY2016 to FY2022, research on electromagnetic acceleration systems was conducted and the target was set to increase the projectile's initial velocity and improve the rail's durability on a single-shot-type 40mm caliber railgun.

It should also be able to survive accelerations of at least 20,000 g (threshold) / 40,000 g (objective) in all axes, high electromagnetic fields (E > 5,000 V/m, B > 2 T), and surface temperatures of > 800 deg C. The package should be able to operate in the presence of any plasma that may form in the bore or at the muzzle exit and must also be radiation hardened owing to exo-atmospheric flight.