Monday, February 05, 2007

Free Electron Laser Toasted Cars at Ground Zero


The U.S. Navy's free electron laser

Raman free-electron laser CHINA

ISRAEL Star Wars survivor

Electron-optical elements of the Free Electron Laser inside the tandem accelerator
US's Star Wars weapons program as "death rays" for felling ballistic missiles attacking via outer space. Today, scientists' aspirations are more peaceable though no less impressive. Potential uses for FEL laser energy are igniting non-polluting nuclear reactors...

The TAU-led project, carried out at a modified van de Graff accelerator at the Weizmann Institute of Science, was funded by the Israeli government, the Israeli Academy of Sciences, the US-Israel Binational Science Foundation, and the Meyer Foundation.

A powerful, 100 kW, infrared free-electron laser for the Photochemistry Center SB RAS

Figure 70. What was this thing across the street? Was it a car? Was it a van? What caused that line of burn marks on the hood of the car in the foreground on the right? In the left foreground, the remains of a vehicle sit atop a white sedan. Are we looking at the front or the back end? It looks like the front end and if it is, its engine is missing. We can see daylight through the wheelwell.

Is there something attractive about engine blocks? Why not gasoline fuel tanks?

Oddly enough, there were also toasted cars at the Pentagon on 9/11

The car with the flat tire appears to have "wilted" from heat, from the top down, leaving a peeling appearance on the back end. The SUV on its right is missing all its window glass except for the windshield. The vehicle on the far right has no trace of tires, no door handles, no tail lights, and no windows. Why?

It was important that 11.September 2001 was a CLOUD FREE day.

A particle beam weapon was used in combination with demolition charges to bring down the WTC towers.

Here is a description of what it looked like:

"As I was running, parked cars were blowing up and some were on fire, the street was cracking a bit as well."

Aftermath photos:

Patricia Ondrovic on 11 oct 2001:
"I saw two other planes. One came in one way, and the other came in the other way, and there
was a plane in the middle that was way far off in the distance. Then the plane in the
middle just disappeared into a little fire ball. It looked like the size of a golf ball from
where I could see it."

WHO would be so evil?
Who would know?

ESTONIA FERRY sank, 800 dead, Russian secret plutonium weapon was aboard, wreck was enclosed by swedisch government in concrete sacophargus, to stop divers to investigate.

The following is an edited transcript of a radio program discussing the Estonia disaster aired on Radio Free America, with host Tom Valentine.

"Back in the mid-1970s, when I was close to becoming involved in the intelligence community, I recall there was a big flap over the Soviets' development of a charged particle x-ray laser weapon that was fueled by super-grade plutonium and would have been spacebased for anti-ballistic missile service. The last generation of the proton missile was designed to deploy it.

The thought occurs to me that this technology... would have fit on one of those trucks that were driven onto Estonia and that it would involve a substantial quantity of super-grade plutonium.

If you put the U.S. system together with the Russian system, you've got something that can not only knock down inter-continental ballistic missiles, but is light enough in multi-use (which means it can be deployed on satellites) and can be used to hit any target on earth."


Nuclear Pumped Laser is a laser where nuclear fission fragments captured in special lasing mixture induce plasmas so that the inversion population of levels corresponds to the laser transition with appropriate wavelengths. The energy stored in the inversion population is extracted from laser cell by the optical system as a laser beam. Application of nuclear fission fragments energy for pumping of laser is a prospect and very promising way because of high energy and efficiency of particles.
Principle of operation of Nuclear Pumped Laser is shown in this figure:

Here: 1 - neutron flux; 2 - fission fragments; 3 - U235 film;
4 - laser medium; 5 - optical windows; 6 - "feedback" mirror;
7 - output mirror; 8 - laser beam.

Neutrons from the ignition reactor passing through the the laser active element (LAEL) are moderated and induce a chain fission reaction of uranium-235 in the coating of LAEL. The fission fragments (high energy ions) captured in lasing mixture induce plasmas with the inversion population of levels. The energy stored in the inversion population is extracted from laser module by the special optical system equipped with "feedback" and output mirrors (so-called "nuclear pumped laser generator").

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Nuclear pumped laser -- From Wikipedia, the free encyclopedia

A nuclear pumped laser is a laser pumped with the energy of fission fragments. The lasing medium is enclosed in a tube lined with uranium-235 and subjected to high neutron flux in a nuclear reactor core. The fission fragments of the uranium create excited plasma with inverse population of energy levels, which then lases. Other methods, e.g. the He-Ar laser, can use the He(n,p)H reaction, the transmutation of helium-3 in a neutron flux, as the energy source, or employing the energy of the alpha particles.

This technology may achieve high excitation rates with small laser volumes.

Some example lasing mediums:
carbon dioxide

External links
IPPE: Principle of operation of nuclear pumped laser - contains a diagram
Abstract: Nuclear pumped laser II

X-ray free electronic laser schema of operation

A free electron laser, or FEL, is a laser that generates tunable, coherent, high power radiation, currently ranging in wavelength from microwaves to the visible spectrum. While an FEL laser beam shares the same optical properties as conventional lasers such as coherent radiation, the operation of an FEL is quite different. Unlike gas or diode lasers which rely on bound atomic or molecular states, FELs use a relativistic electron beam as the lasing medium, hence the term free-electron. Free electron lasers can be used to generate terahertz radiation.Contents [hide]

FEL creation

To create an FEL, a beam of electrons is accelerated to relativistic speeds. The beam passes through a periodic, transverse magnetic field. This field is produced by arranging magnets with alternating poles along the beam path. This array of magnets is sometimes called an undulator, or a "wiggler", because it forces the electrons in the beam to assume a sinusoidal path. The acceleration of the electrons along this path results in the release of a photon (bremsstrahlung or synchrotron radiation, but not in the most common sense of either term).

Viewed relativistically in the rest frame of the electron, the magnetic field can be treated as if it were a virtual photon. The collision of the electron with this virtual photon creates an actual photon (Compton scattering). Mirrors capture the released photons to generate resonant gain. Adjusting either the beam energy (speed/energy of the electrons) or the field strength tunes the wavelength easily and rapidly over a wide range. Because compton scattering is complicated in itself, it is easier to say that the electrons are forced onto a sinus path by the undulator and then switch in a rest frame moving along the undulator, where the electrons are oscillating, but not moving otherwise, and emit dipole radiation, and than switch back into the rest frame of the undulator to see that this dipole radiation is transformed into a forward emitted radiation of shorter wavelength.

Since the photons emitted are related to the electron beam and magnetic field strength, an FEL can be tuned, i.e. the frequency or color can be controlled.

What makes it a laser (light amplification by stimulated emission of radiation) is that the electron motion is in phase (coherent) with the field of the light already emitted, so that the fields add coherently. Since the intensity of light depends on the square of the field, this increases the light output. (Surprisingly, quantum mechanics is not required in this explanation.). In the rest frame moving along the undulator any radiation will still move with the speed of light and pass over the electrons and lets them communicate to get in synchronization. Often same light (that is radiation) is introduced from the outside. Depending on the position along the undulator the oscillation of an electrons is in phase or not in phase with this radiation. The light either tries to accelerate or decelerate these electrons. It thereby gains or loses kinetic energy, so it moves faster or slower along the undulator. This causes the electrons to form bunches. Now they are synchronized, and will in turn emit synchronized (that is coherent) radiation.


Today, a free electron laser requires the use of an electron accelerator with its associated shielding, as accelerated electrons are a radiation hazard. These accelerators are typically powered by klystrons, which require a high voltage supply. Usually, the electron beam must be maintained in a vacuum which requires the use of numerous pumps along the beam path. Free electron lasers can achieve very high peak powers. Their tunability makes them highly desirable in several disciplines, including medical diagnosis and non-destructive testing.

From the klystron to the free electron laser


In a klystron an electron beam is accelerated by a 200 kV DC electric field. An electromagnetic wave interacts with it, modulating its velocity. In a drift tube this velocity distribution is converted to a density modulation. In a second interaction region energy can be converted from the electron beam to the EM-wave or vice versa depending on the relative phase with which both are fed. If energy is converted to the EM-wave, this device is called a klystron, otherwise it is an linear electron accelerator (linac).

Interaction devices

In a klystron or linac the wavelength of the EM-wavelength is larger than the electron beam and various waveguide structures can be used to slow down the EM-field to speed of the electron density (group) velocity and at the same time provide E-fields in the direction of the electron motion.

In a gyrotron or free electron laser the EM-wavelength is smaller than the electron beam and the electrons have to be manipulated. Magnetic fields force them on a sinusoidal path, so as the EM-wave overtakes them and the E-vector changes sign, the electrons change direction.

Most interaction devices are tunable, but only a family of waveguides called traveling wave tubes allows one octave wide instant bandwidth and thus short pulses, but have cooling problems as they consist of helical wires or wire chambers.

Quantum noise

The amplified wave can be fed back thus producing an oscillator. Free electron lasers in the visible region and above are so energy hungry that operation is only possible for short durations. Lasers start up from quantum noise (optical shot noise), which is damped over time, which these energy hungry beasts don’t have, producing very unstable output.

X-ray FELs

The lack of suitable mirrors in the extreme ultraviolet and x-ray regimes prevent the operation of an FEL oscillator; consequently, there must be suitable amplification over a single pass of the electron beam through the undulator to make the FEL worthwhile. When the field extracts enough energy from the electrons over a single pass such that the field amplitude cannot be regarded as constant during the FEL process, the FEL is said to operate in the high-gain regime. In this case one can couple the single particle equations of motion to Maxwell's equations by describing the beam phase space via the Klimontovich distribution and using this distribution to source the paraxial wave equation for the slowly-varying electric field amplitude. Thereby the paraxial wave equation, together with the continuity equation, completely determine the dynamics of the field and beam during the FEL process.

Self-Amplified Spontaneous Emission

It is a fascinating fact that even if the initial field amplitude is zero, the FEL can still generate a laser through the process of Self-Amplified Spontaneous Emission (SASE); whereby, the (classical) shot noise due to density perturbations in the electon beam causes a noisy signal to be initially radiated. The FEL process preferentially selects a single, transveresly coherent mode from this noise to amplify till the energy spread in the beam, created by the FEL interaction, dominates causing the FEL to saturate at some high power. The Linac Coherent Light Source (LCLS), currently under construction at the Stanford Linear Accelerator, will operate as a SASE FEL, radiating at wavelengths down to 1.5 angstroms.

Seeded FELs

One problem with SASE FELs is the lack of temporal coherence due to the noisy startup process. To avoid this one can "seed" an FEL with a laser, produced by more conventional means, tuned to the resonance of the FEL. This results in coherent amplification of the input signal such that the output laser quality is characterized by the seed. Although, this method becomes a problem at x-ray wavelengths because of the lack of conventional x-ray lasers. Of course this problem can also be overcome by employing the method of High Gain Harmonic Generation (HG2), whereby one first uses an undulator to create bunching at higher harmonics of the seed laser, then in an upstream undulator tuned to a higher harmonic of the seed one uses this bunching to radiate at that higher harmonic. For example starting with a 240 nm UV seed, one could "go to the eighth harmonic" and radiate in the second undulator at 30 nm XUV light.

Energy flow at the XFEL at DESY
The big picture (ed. Numbers may be incorrect due to author speculation)

Lets start with a 10 kV 3 phase 50 Hz outlet. Solid state technology converts it to 200 kV 1 kHz 1 µs square pulse voltage. This EM-energy is converted to kinetic electron energy. Klystrons convert this to 2 GHz AC EM-waves. A Linac converts this EM-wave energy to a high energy electron beam energy. A free electron laser converts this energy to 100+ THz EM-Waves.

Medical applications

At the 2006 annual meeting of the American Society for Laser Medicine and Surgery (ASLMS), Dr. Rox Anderson of the Wellman Laboratory of Photomedicine of Harvard Medical School and Massachusetts General Hospital reported on the possible medical application of the free electron laser. It was reported that at infrared wavelengths, water in tissue was heated by the laser, but at 915, 1210 and 1720 nm, subsurface lipids were differentially heated more strongly than water. The possible applications include the selective destruction of sebum lipids to treat acne, as well as targeting other lipids for the treatment of cellulite and atherosclerosis. [1]

Military applications

FEL is also considered by US Navy as a good candidate for anti-missile directed-energy weapon. Significant progress is being made in increasing FEL power levels (already at 10 kW) and it should be possible to build compact multi-megawatt class FEL lasers (Airborne megawatt class free-electron laser for defense and security).

Brau, et al. U.S. Patent 4189686 "Combination free electron and gaseous laser", February 19, 1980.
Brau, et al., U.S. Patent 4287488 , "Rf Feedback free electron laser", September 1, 1981.
Gover, U.S. Patent 4367551 , "Electrostatic free electron laser", January 4, 1983.
Brau, et al., U.S. Patent 4442522 , "Circular free-electron laser", April 10, 1984.
Smith, et al., U.S. Patent 4449219 , "Free electron laser", May 15, 1984.
Madey, U.S. Patent 4479219 , "Excitation cancelling free electron laser", October 23, 1984.
Prosnitz, et al., U.S. Patent 4506229 "Free electron laser designs for laser amplification", March 19, 1985.
Bhowmik, et al., U.S. Patent 4698815 , "Efficiency enhanced free electron laser", October 6, 1987.
Brau, et al., U.S. Patent 4479218 , "Free electron laser using Rf coupled accelerating and decelerating structures", October 23, 1984
Madey, et al., U.S. Patent 4740973 , "Free electron laser", April 26, 1988.
Villa, U.S. Patent 4972420 , "Free electron laser", November 20, 1990.
Szoke, et al., U.S. Patent 4500843 , "Multifrequency, single pass free electron laser", February 19, 1985.
Madey, et al., U.S. Patent 6636534 , "Phase displacement free-electron laser", October 21, 2003.

See also
TESLA particle accelerator

Further reading
Boscolo, et al., "Free-Electron Lasers and Masers on Curved Paths". Appl. Phys., (Germany), vol. 19, No. 1, pp. 46-51, May 1979.
Deacon et al., "First Operation of a Free-Electron Laser". Phys. Rev. Lett., vol. 38, No. 16, Apr. 1977, pp. 892-894.
Elias, et al., "Observation of Stimulated Emission of Radiation by Realistic Electrons in a Spatially Periodic Transverse Magnetic Field", Phys. Rev. Lett., 36 (13), 1976, p. 717.
Gover, "Operation Regimes of Cerenkov-Smith-Purcell Free Electron Lasers and T. W. Amplifiers". Optics Communications, vol. 26, No. 3, Sep. 1978, pp. 375-379.
Gover, "Collective and Single Electron Interactions of Electron Beams with Electromagnetic Waves and Free Electrons Lasers". App. Phys. 16 (1978), p. 121.
"A Unified Theory of Magnetic Bremsstrahlung, Electrostatic Bremsstrahlung, Compton-Raman Scatering and Cerenkov-Smith-Purcell Free Electron Laser".
"The FEL Program at Jefferson Lab" [2]

Free Electron Laser Open Book (National Academies Press)
The World Wide Web Virtual Library: Free Electron Laser research and applications
The European X-Ray Laser Project XFEL
Electron beam transport system and diagnostics of the Dresden FEL
W. M. Keck Free Electron Laser Center
Duke University Free Electron Laser Laboratory
Free-Electron Lasers: The Next Generation by Davide Castelvecchi New Scientist, January 21, 2006
Airborne megawatt class free-electron laser for defense and security

External links

Estonia Particle Weapon poofed WTC towers?
On 23 March, Tom Valentine of Radio Free America interviewed veteran nuclear physicist Galen Winsor, who said the blast was not caused by a low-yield conventional explosive charge. Galen Winsor went much further than this. "I'm sure it was just exactly what John McPhee predicted 20 years ago in his book, The Curve of Binding Energy" he said, "where McPhee quoted Theodore B. Taylor, a theoretical physicist out of Los Alamos, who said that someone someday was going to blow up the World Trade Centre with a small nuclear device, the size of a stick of gum." Winsor continued, "McPhee's book was published in 1975, although the prediction first appeared in the New Yorker magazine in 1973. Taylor worked in the area of the micronization of nuclear weapons, in other words making nuclear weapons small enough so the Israelis could carry them around in a briefcase."
At first glance the thought of micronized nuclear weapons being used in major cities seems absurd, but there is now considerable evidence indicating strongly that small nuclear devices were also responsible

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