A PASER (an acronym from ''Particle Acceleration by Stimulated Emission of Radiation)'' is a device that accelerates a coherent beam of

electrons The electron ( or ) is a subatomic particle with a negative one elementary electric charge. Electrons belong to the first generation of the lepton particle family, and are generally thought to be elementary particles because they have no ...

. This process was demonstrated for the first time in 2006 at the Brookhaven National Lab by a team of physicists from the Technion-Israel Institute of Technology. American Institute of Physics (2006), "Particle Acceleration by Stimulated Emission of Radiation -- PASER for Short, webpage: http://www.aip.org/pnu/2006/split/792-1.html {{Webarchive, url=https://web.archive.org/web/20080502185219/http://www.aip.org/pnu/2006/split/792-1.html , date=2008-05-02 , accessed 2006-11-25. Relativistic electrons from a conventional

particle accelerator A particle accelerator is a machine that uses electromagnetic fields to propel charged particles to very high speeds and energies, and to contain them in well-defined beams. Large accelerators are used for fundamental research in particle ...

pass through a vibrationally excited

carbon dioxide Carbon dioxide ( chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is trans ...

medium in which the electrons undergo millions of collisions with excited carbon dioxide molecules and are accelerated in a coherent fashion. No heat is generated in this quantum energy transfer, thus all the energy transferred to the electrons is used in accelerating the electrons. The electron beam created from this process may result in electrons that are highly collimated in velocity in comparison to other acceleration methods. The vibrationally excited carbon dioxide is the same medium used in a

carbon dioxide laser The carbon-dioxide laser (CO2 laser) was one of the earliest gas lasers to be developed. It was invented by Kumar Patel of Bell Labs in 1964 and is still one of the most useful types of laser. Carbon-dioxide lasers are the highest-power contin ...

. This medium resonantly amplifies light with a wavelength near 10.6 or 9.4

micrometers The micrometre ( international spelling as used by the International Bureau of Weights and Measures; SI symbol: μm) or micrometer (American spelling), also commonly known as a micron, is a unit of length in the International System of Unit ...

, corresponding to a frequency of approximately 30 terahertz. In order to be accelerated, incident electrons must be microbunched at this frequency. An appropriately bunched electron beam strikes excited carbon dioxide molecules resonantly in order to efficiently stimulate energy emission.

References

Electron Particle accelerators

See also

References