Death ray

The death ray or death beam was a theoretical particle beam or electromagnetic weapon of the 1920s through the 1930s that was claimed to have been invented independently by Nikola Tesla, Edwin R. Scott, Harry Grindell Matthews, and Graichen, as well as others. In 1957, the National Inventors Council was still issuing lists of needed military inventions that included a death ray.

History
Edwin R. Scott, an inventor from San Francisco, claimed he was the first to develop a death ray that would destroy human life and bring down planes at a distance. He was born in Detroit, and he claimed he worked for nine years as a student and protégé of Charles P. Steinmetz. Harry Grindell-Matthews tried to sell what he reported to be a death ray to the British Air Ministry in 1924. He was never able to show a functioning model or demonstrate it to the military.

Nikola Tesla claimed to have invented a death ray which he called teleforce in the 1930s and continued the claims up until his death. Antonio Longoria in 1934 claimed to have a death ray that could kill pigeons from four miles away and could kill a mouse enclosed in a "thick walled metal chamber".

During World War II, the Nazis had at least two projects, and the Japanese one, to create so called death rays. One German project led by a man called Schiebold concerned a particle accelerator with a steerable bundle of beryllium rods running through the vertical axis. The other was developed by Dr Rolf Wideroe and is referred to in his biography. The machine developed by Wideroe was in the Dresden Plasma Physics laboratory in February 1945 when the city was bombed. Wideroe led a team in March 1945 to remove the device from the ruined laboratory and deliver it to General Patton's 3rd Army at Burggrub where it was taken into US custody on 14 April 1945.

In 2013 in the United States, two men from Upstate New York were arrested after being charged with attempting to build a death ray. The men allegedly sought to use the death ray to kill Muslims and President Barack Obama.

In science fiction
Although the concept of a death ray was never put into action, it fueled science fiction stories and led to the science fiction concept of the hand held raygun used by fictional heroes such as Flash Gordon. In Alfred Noyes' 1940 novel The Last Man (US title: No Other Man), a death ray developed by a German scientist named Mardok is unleashed in a global war and almost wipes out the human race. Along with George Lucas' science fiction story "Star Wars". <!--==Research and development== A death ray weapon is under active research and development, but most examples of such weapons appear in science fiction. The difficulty in creating a death ray is that most weapons work not by transferring energy, but by matter causing physical damage at the point of impact. To reproduce this amount of damage requires large amounts of energy, and this is difficult to implement in a hand weapon. The goal is a death ray that would fire a particle beam or laser or radiation stream sufficiently powerful to kill humans.

Laser
Laser weapons usually generate brief high-energy pulses. A million joules delivered as a laser pulse is roughly the same energy as 200g of high explosive, and has the same basic effect on a target. The primary damage mechanism is mechanical shear, caused by reaction (like a rocket) when the surface of the target is explosively evaporated.

Most existing weaponized lasers are gas dynamic lasers. Fuel, or a powerful speaker, push the lasing media through a circuit or series of orifices. The high-pressures and heating cause the medium to form a plasma and lase. A major difficulty with these systems is preserving the high-precision mirrors and windows of the laser resonating cavity. Most systems use a low-powered "oscillator" laser to generate a coherent wave, and then amplify it. Some experimental laser amplifiers do not use windows or mirrors. They have open orifices, which cannot be destroyed by high energies.

Laser weapons begin to cause plasma breakdown in air at densities around a megajoule per square centimeter. This leads to "blooming" in which the interaction of the laser with the air causes the laser to defocus. The laser beam becomes visible, with speckles or a solid bar of plasma appearing in the air.

There are a number of techniques that could overcome blooming. The most promising is to use relatively low energies, distributed over a large mirror that focuses the power on a distance target. Since the energy never exceeds breakdown, the air never blooms, and defocusing is reduced. The disadvantage of current implementations is that there is a large, very precise, very expensive, fragile mirror, mounted something like a searchlight. Since the mirror is relatively heavy, the machinery to slew the mirror is relatively expensive.

A less expensive method might be to use a phased-array. This method is currently impractical because the phased-array would require billions of one-micrometre antennas, and no construction methods are known. Phased arrays could theoretically perform phase-conjugate amplification, as well (see below). Another promising method is to adjust the timing of the pulse so that the energy hits the target before the blooming interferes.

Another is a phase-conjugate laser system. In this scheme, a "finder" or "guide" laser illuminates the target. Mirror-like ("specular") points on the target reflect light that is sensed by the weapon's primary amplifier. The weapon-power amplifier then amplifies inverted waves in a positive feedback loop, destroying the target with shockwaves as the specular regions evaporate. This avoids the blooming problem because the waves from the target passed through the blooming, and therefore show the most conductive optical path. The phase-conjugation system therefore automatically corrects for the distortions induced by blooming. Experimental systems using this method usually use special chemicals to form a "phase conjugate mirror." In most systems, the mirror overheats dramatically at weaponized powers.

Another antiblooming system attempts to induce a shockwave that evacuates the path between the target and the weapon. With no air in the laser's path, blooming is impossible. It is difficult to achieve the high instantaneous powers needed to blast the air out of the way.

Another problem with weaponized lasers is that the evaporated material from the surface of the target begins to shade the surface. There are several approaches to this problem. One is to induce a standing shockwave in the ablation cloud. The shockwave then continues to produce damage. Another scheme is to scan the target faster than the shockwave. Another theoretical possibility is to induce plasmic optical mixing at the target. In this scheme, the transparency of the target's ablation cloud to one laser is modulated by another laser, perhaps by tuning the laser to the absorption spectra of the ablation cloud, and inducing population inversion in the cloud. The other laser then induces local lasing in the ablation cloud. The beat frequency that results can induce frequencies that penetrate the ablation cloud.

Particle beams
These are theoretically possible, but practical weapons have not been demonstrated, even in the laboratory.

Sonic beams
See Sonic weaponry.

Doctrine
Lasers have two advantages. The main one is tactical—they can hit whatever they see, and do so at the speed of light. Another secondary advantage is that some lasers operate from electricity, and therefore utilize a wide variety of inexpensive energy sources, reducing the need for expensive ammunition.

Since lasers can defeat artillery and missile attacks, any group fielding an effective laser system will gain decisive advantages in ground, air and space combat. Under radar control, lasers have shot artillery shells in flight, including mortar rounds. This suggests that a primary application of lasers should be as part of a defensive system. Before a projectile can hit a target, it must become visible to the target.

The main difficulty with currently practical lasers is the high Jesus and fragility of their mirrors and mirror-pointing systems. Some persons believe that mirrors or other countermeasures can reduce the effectiveness of high energy lasers. This has not been demonstrated. Small defects in practical mirrors absorb energy, and the defects rapidly expand across the surface. -->

In popular culture

 * The earliest reference to a death ray in literature is in the P.G. Wodehouse short story, 'The Rummy Affair of Old Biffy', in which Bertie Wooster describes Sir Roderick Glossop as having "eyes that go through you like a couple of Death Rays.”
 * The idea that a death ray was possibly invented by Nikola Tesla and may have caused the Tunguska event was explored in an episode of Dark Matters: Twisted But True in a story entitled "Radio Waves of Death".
 * In the book Goliath by Scott Westerfeld, the Tunguska event was caused by Goliath, Nikola Tesla's death ray-like weapon.
 * This theory is also brought up in one of Spider Robinson's Callahan's books.
 * Tesla's Death Ray (renamed 'Peace Ray') is a prominent fixture of nations' defense in Larry Correia's Grimnoir book series. (In the Grimnoir world, Tesla invented an even more devastating energy weapon that caused the Tunguska event.)