Even before the age of sail with its famous frigates and ships of the line full of cannons man has been putting long-range weapons aboard ships. Early naval vessels were often equipped with catapults or ballistic and their purpose was much the same as it remains today. Help soften up enemy coastal defenses or destroy other ships at sea.
High-powered lasers can burn out a missile guidance system at a long-range, powerful jamming pod can interfere with the missiles targeting, electronic warfare suites can even hack into missile's active guidance and disrupt it and smaller more agile Missiles or high-speed Computer-controlled Chain guns can intercept them mid-flight. While a saturation strike involving Multiple missile volleys can overwhelm even the U.S.'s vaunted Aegis Missile Defense system. There still seems to be room for traditional artillery but it wasn't until recent technological development produced an alternative to modern missiles that was even remotely comparable. Even the big guns of World War II Arab battleships were too slow to fire and the projectiles lacked enough velocity to reliably strike their targets.
In essence, a railgun is nothing more than a large Electrical circuit that uses magnetism to accelerate a projectile to greater speeds than possible by traditional gunpowder charges or even most missiles. The railgun consists of three parts:
A Power source
A pair of parallel rails
A moving armature
The power supply Generates current in the millions of Amps or enough to power a few thousand homes. The rails are long lengths of a highly conductive metal such as copper and could range from four to thirty feet ( 1 to 9 meters ) long.
Some railguns, such as the American naval prototype use a plasma armature or a thin metal foil that is placed on the back of the non- conducting projectile. As the millions of Watts flow through the foil, it vaporizes and becomes plasma, which conducts the Current. To fire, the railgun discharges Power from the positive terminal of the Power supply and up the positive rail. The current then leaps across the Armature and down the negative rail and back to the Power supply.
As Michael Faraday taught us, a current flowing through a wire creates a magnetic field, which has both a magnitude and direction. The magnitude of this field indicates how powerful the Field is and the direction is the way the force lines of the magnetic field run. When the railgun is powered up and the current flows from one rail to the other the two rails act like wires with a magnetic field circulating around each rail. The force lines of the magnetic field run counterclockwise in the Positive rail and clockwise around the Negative rail, so the net magnetic field between the rails is directed vertically.
The Lorentz force is also parallel to the two rails pushing the projectile away from the power supply and thus firing it like a cannon shell. Railgun projectiles are inert, meaning they have no explosive charge whatsoever. Instead, they rely on Isaac Newton's Second law of motion - Force equals Mass Times Acceleration.
Basically, the projectile is accelerated to incredible speeds, imparting it with extraordinary amounts of kinetic energy. When the projectile reaches its target and then imparts all that kinetic energy to its target with devastating results. In fact, rail guns could potentially outdo typical chemical warhead missiles and sheer destructive potential as traditional explosives are inherently limited in the amount of energy that can release by the energy potential of the materials used to create them.
The technical problems remain numerous up until recently the US Navy, in charge of developing the railgun for US ships, was having problems generating the power sufficient to continuously fire the railgun. Then as Power issues were sorted out and Wattages increased, the rails began to experience serious warping and melting as the Navy tried to reach the Pentagon's requirement that the railgun fire at a rate of 10 projectiles a minute, eventually only hitting 4.8 rounds a minute for fear of damaging the delicate rails. Yet technical problems can and have been largely overcome - the rail warping which may require further investment in material science to develop conductive materials capable of withstanding the incredible wattage coursing through it.
Yet critics of the Pentagon's decision to divert resources from pure railgun research point out (rightfully so) that a traditional powder projectile will never achieve the same performance as that offered by the railgun. While the railgun no doubt offers far greater benefits, the sad reality is that the Pentagon is currently extremely wary of big expensive weapons projects after spending billions on the F-35.
With Mark 45, 5-inch guns already installed on Every U.S. ship, the appeal of the hypervelocity projectile over a futuristic railgun is far greater. Currently, the future of the US's railgun is in serious question, and while most predict that a railgun will eventually be developed that may come far too late for the U.S. to maintain its technological advantage over its adversaries.
In the last years of the Cold War, the Soviet Union's development of the Akula Class nuclear submarine surprised every Western observer who did not think the Russians would be capable of building such a sub for at least 10 more years.
More worrisome for Washington, if the Chinese have truly mastered a working Railgun and will follow through on their stated plans to install them on their Ships by 2025, it could signal the end of the U.S.'s absolute dominance of the Pacific Ocean and complicate the strategic picture for regional allies who fear China's South China Sea Aggression.