Rail Guns and Laser Beams

Those pesky Naval weaponry developers have been at it again.

I have always been interested in Naval weapons development.  Back in the late 1980's I had a company that was looking at work from various defense agencies.  We made a sales trip to the Naval weapons storage facility in Indiana (Naval Surface Warfare Center Crane Division).

After entering the main gate you drove past what seemed like miles of "bunkers" - "bunkers" containing charges for the large naval guns.  Once we arrived at the main building out front was a mock Polaris missile.  The bunkers all contain the charges used to propel large shells from the big on-deck naval guns.  Since the charges are affected by age and other factors the Navy keeps close track of their age.

The bunkers themselves look like Indian mounds with a slot cut through one end.  The slot is lined with concrete on both sides.  This is so if there is an explosion the blast will be deflected away from other mounds.

Fascinating stuff...

But not a as fascinating as some recent Naval weapons developments...

First there is the "Mach-8 Rail Gun" (see the video here).  The idea is replacing all those endless miles of charges in bunkers with a big, powerful electromagnetic system that can launch a piece of metal just as far - no gun powder, no danger.  The idea is that you charge up a big bank of capacitors (devices that store electrical energy when the power - sort of like you when you walk around a dry house in the winter building up a static electrical charge - except there is real current involved in this).  You discharge the capacitors through a coil of wire that makes a magnetic field.  The magnet field, coil of wire and capacitors are all designed to start pulling the "shell" into the field of the magnet on the discharge.  As the shell accelerates into the magnetic field the charge dissipates and the shell keeps going.

Going at about 6,000 feet per second - that's about six times faster than a rifle bullet.

There is no reverse recoil as with a traditional powder-fired shell and you can knock incoming missiles, planes, and drones out of the sky with deadly efficiency.

But, if you don't like actually firing "shells" - even simple metallic ones at incoming weapons there is always the new death ray.  This the FEL or free-electron laser.  The idea of this is that to get enough power to create a laser beam that can knock incoming planes, shells and other weapons out of the air you need a lot of energy in your laser beam - more than you can get by simply using light by itself.

So the FEL uses an accelerator to generate a high-energy beam of electrons instead.  A big magnetic "ring" is created to hold the electrons.  Electrons are injected into the ring and the magnets are used to accelerate the electrons around the ring at nearly the speed of light.  Once accelerated the electrons are used to stimulate the laser activity.

This is done by passing the electron beam through a lasing cavity to create a laser beam.  The electron beam is synchronized (made coherent) with the laser activity in the cavity to create the most powerful laser on the planet.  The power of the laser depends on how many electrons are used - more electrons means more power.

The FEL laser can be tuned to multiple frequencies at the same time in order to allow it to pass easily through the air to reach its target.

So, like the rail gun, the Navy is wisely replacing traditional shells and gun powder with magnets and electrons.  Unfortunately it will probably take at least eight to ten more years before these weapons are actually in use on ships.