April 8, 2014 – Yesterday the American navy announced it plans to install an EM weapon on one of its ships in 2016. EM stands for electromagnetic. These weapons accelerate and launch projectiles by guiding them down two conductive rails at such high velocity that they can launch them over 200 kilometers (110 nautical miles). They work using Lorentz Force, named after a Dutch physicist, Hendrik Antoon Lorentz, who discovered that an electric force on a charged particle parallels the local electric field. The magnetic force lies perpendicular to the direction of the particles motion.
A railgun consists of a three-part structure, a power source, a pair of parallel rails and a projectile platform on which is housed anything from an artillery shell to a rocket. A high-powered million-amp electric current runs from the positive rail across the projectile platform to the negative rail and then back to the power source. In the case of the navy, that power comes from the ships engines. The two rails act like wires and the current running through them creates two magnetic fields one running counterclockwise around the positive rail and the other clockwise around the negative rail. The combination of the two magnetic fields creates the energy to drive the platform along the rails. Depending on the rail length and the amount of power a projectile can be launched at speeds of Mach 5 or more. That’s over 6,000 kilometers (3,730 miles) per hour. Extend the length of the rail gun and increase the amperage and you have a gun that can put a satellite in orbit.
When air power ended the age of battleships no one envisioned their revival, but railgun technology represents a new level of lethality for naval ships to use against threats from the air, land or ocean, a new era for a new kind of battleship. And compared to other projectile weapon systems such as missiles, it turns out that railguns are far less expensive to operate. So I expect that the United States will in building ships with EM guns begin a process we have seen before in history.
At the beginning of the 20th century the British brought out a revolutionary, heavily armored battleship, HMS Dreadnought. It made all previous warships obsolete and led to a global arms race that inevitably contributed to the eruption of the First World War.
Could we consider using railguns for another purpose or is it inevitable that we always begin by exploiting the science to build a weapon? Can Lorentz Force power transportation? Imagine trains and suborbital commercial transportation using this type of technology. It seems almost certain that this is a path worth exploring.
Can what Lorentz discovered help us to develop other types of magnetic force technologies such as shields to protect humans from cosmic rays in space habitats? If so then maybe this military invention will spawn a range of peaceful applications.