Re: US developing untraceable weapons
Well, there was also some other details left out by that article. A "100kW beam" doesn't tell you very much if you don't know the beam diameter. A 1310nm telecom laser can cause serious eye damage with 10mW, but that's 10mW into, say 38 um^2. But it ain't going to do nothing to enemy aircraft located at a distance. A 100kW laser might easily have a smaller energy density depending on the diameter. In addition, there's the problem of focusing that thing through turbulence, but turbulence through certain wavelength windows may not be a problem.
From: Steve Schear <schear@lvcm.com> To: cypherpunks@lne.com Subject: Re: US developing untraceable weapons Date: Sat, 12 Oct 2002 17:28:03 -0700
At 12:10 PM 10/11/2002 -0700, "Major Variola (ret)" <mv@cdc.gov> wrote:
Theres no huge explosion associated with its employment, there are no pieces and parts left behind that someone can analyze to say, this came from the United States, explains an unnamed Lockheed Martin official quoted in Aviation Week and Space Technology in July. The damage is localized, and it is hard to tell where it came from and when it happened. It is all pretty mysterious.
The only energy sources I can think of that is portable enough to go in a jet are a generator running of the main/aux jet engine or a chemical pumping.
Unless the DoD has found a practical new chemical reaction, other than the Fluorine/Deuterium they used for decades on various shipboard project such as MIRACL, the plane would be easily identified and targeted by the fluorescing the chemical plume with LIDAR.
Assuming a laser efficiency of 5% an electric source would have to provide over 2 MW of continuous power (from Star Wars test results, I assume a pulsed laser is inadequate for causing damage in combat situations) to supply a 100KW beam. The most efficient generators I'm aware are capable of producing about 2-4 HP/lb. 2 MW equates to about 2700 HP or about 650 - 1300 lbs. Assuming the laser isn't too terribly heavy or aerodynamically cumbersome the entire package could be carried aboard a fighter.
steve
"War is just a racket ... something that is not what it seems to the majority of people. Only a small group knows what its about. It is conducted for the benefit of the very few at the expense of the masses." --- Major General Smedley Butler, 1933
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At 10:17 PM 10/12/2002 -0400, Tyler Durden wrote:
Well, there was also some other details left out by that article. A "100kW beam" doesn't tell you very much if you don't know the beam diameter.
It tells you the output power, from which one may estimate input power requirements.
A 1310nm telecom laser can cause serious eye damage with 10mW, but that's 10mW into, say 38 um^2. But it ain't going to do nothing to enemy aircraft located at a distance. A 100kW laser might easily have a smaller energy density depending on the diameter. In addition, there's the problem of focusing that thing through turbulence, but turbulence through certain wavelength windows may not be a problem.
Beam spread is one of the most significant considerations in delivering high energy to distant targets. In general, one wants a large beam size to reduce divergence. The phenomenon of diffraction influences the propagation of Gaussian light beams. The output of a laser is generally ''pencil-like'' in nature and has a very low divergence, yet is subject to diffraction that causes it to spread. Gaussian beam theory deals with this effect. The Rayleigh range, Z sub R, is used as a criterion for determining the spreading of a monochromatic Gaussian light beam as it propagates in free space. In 1987 it was discovered that were ''nondiffracting'' beam types. The zeroth-order Bessel beam is one such solution and results in a beam with a narrow central region surrounded by a series of concentric rings. Ideally this beam type exhibits no diffraction or spreading, in practice it is possible to obtain Bessel beams of less than 1/10 the divergence of a Gaussian beam of otherwise similar properties. Bessel beams have been the subject of intense investigastion for a broad range of optical applications. http://www.st-and.ac.uk/~atomtrap/papers/AJPBessel.pdf http://www.st-and.ac.uk/~atomtrap/Research/IBB.htm
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Tyler Durden