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A laser is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation. The word "laser" is an acronym for "light amplification by stimulated emission of radiation". The first laser was built in 1960 by Theodore H. Maiman at Hughes Research Laboratories, based on theoretical work by Charles Hard Townes and Arthur Leonard Schawlow.
Stimulated emission is the process by which an incoming photon of a specific frequency can interact with an excited atomic electron, causing it to drop to a lower energy level. The liberated energy transfers to the electromagnetic field, creating a new photon with a frequency, polarization, and direction of travel that are all identical to the photons of the incident wave. This is in contrast to spontaneous emission, which occurs at a characteristic rate for each of the atoms/oscillators in the upper energy state regardless of the external electromagnetic field.
A klystron is a specialized linear-beam vacuum tube, invented in 1937 by American electrical engineers Russell and Sigurd Varian, which is used as an amplifier for high radio frequencies, from UHF up into the microwave range. Low-power klystrons are used as oscillators in terrestrial microwave relay communications links, while high-power klystrons are used as output tubes in UHF television transmitters, satellite communication, radar transmitters, and to generate the drive power for modern particle accelerators.
Plasma diagnostics are a pool of methods, instruments, and experimental techniques used to measure properties of a plasma, such as plasma components' density, distribution function over energy (temperature), their spatial profiles and dynamics, which enable to derive plasma parameters.
An undulator is an insertion device from high-energy physics and usually part of a larger installation, a synchrotron storage ring, or it may be a component of a free electron laser. It consists of a periodic structure of dipole magnets. These can be permanent magnets or superconducting magnets. The static magnetic field alternates along the length of the undulator with a wavelength . Electrons traversing the periodic magnet structure are forced to undergo oscillations and thus to radiate energy. The radiation produced in an undulator is very intense and concentrated in narrow energy bands in the spectrum. It is also collimated on the orbit plane of the electrons. This radiation is guided through beamlines for experiments in various scientific areas.
A free-electron laser (FEL) is a synchrotron light source producing extremely brilliant and short pulses of synchrotron radiation. An FEL functions and behaves in many ways like a laser, but instead of using stimulated emission from atomic or molecular excitations, it employs relativistic electrons as a gain medium. Synchrotron radiation is generated as a bunch of electrons passes through a magnetic structure. In an FEL, this radiation is further amplified as the synchrotron radiation re-interacts with the electron bunch such that the electrons start to emit coherently, thus allowing an exponential increase in overall radiation intensity.
The Smith–Purcell effect was the precursor of the free-electron laser (FEL). It was studied by Steve Smith, a graduate student under the guidance of Edward Purcell. In their experiment, they sent an energetic beam of electrons very closely parallel to the surface of a ruled optical diffraction grating, and thereby generated visible light. Smith showed there was negligible effect on the trajectory of the inducing electrons. Essentially, this is a form of Cherenkov radiation where the phase velocity of the light has been altered by the periodic grating. However, unlike Cherenkov radiation, there is no minimum or threshold particle velocity.
A gyrotron is a class of high-power linear-beam vacuum tubes which generates millimeter-wave electromagnetic waves by the cyclotron resonance of electrons in a strong magnetic field. Output frequencies range from about 20 to 527 GHz, covering wavelengths from microwave to the edge of the terahertz gap. Typical output powers range from tens of kilowatts to 1–2 megawatts. Gyrotrons can be designed for pulsed or continuous operation. The gyrotron was invented by Soviet scientists at NIRFI, based in Nizhny Novgorod, Russia.
A PASER is a device that accelerates a coherent beam of electrons. 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.
Sound amplification by stimulated emission of radiation (SASER) refers to a device that emits acoustic radiation. It focuses sound waves in a way that they can serve as accurate and high-speed carriers of information in many kinds of applications—similar to uses of laser light.
High harmonic generation (HHG) is a non-linear process during which a target is illuminated by an intense laser pulse. Under such conditions, the sample will emit the high harmonics of the generation beam. Due to the coherent nature of the process, high harmonics generation is a prerequisite of attosecond physics.
The European X-Ray Free-Electron Laser Facility is an X-ray research laser facility commissioned during 2017. The first laser pulses were produced in May 2017 and the facility started user operation in September 2017. The international project with twelve participating countries; nine shareholders at the time of commissioning, later joined by three other partners, is located in the German federal states of Hamburg and Schleswig-Holstein. A free-electron laser generates high-intensity electromagnetic radiation by accelerating electrons to relativistic speeds and directing them through special magnetic structures. The European XFEL is constructed such that the electrons produce X-ray light in synchronisation, resulting in high-intensity X-ray pulses with the properties of laser light and at intensities much brighter than those produced by conventional synchrotron light sources.
An X-ray laser is a device that uses stimulated emission to generate or amplify electromagnetic radiation in the near X-ray or extreme ultraviolet region of the spectrum, that is, usually on the order of several tens of nanometers (nm) wavelength.
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.
An energy recovery linac (ERL) provides a beam of electrons used to produce x-rays by synchrotron radiation. First proposed in 1965 the idea gained interest since the early 2000s.
Super radiant emission or coherent emission, is an emitted radiation with constant wave direction and rate that occurs in Fourier function. It is emitted when all electrons radiate in phase with each other, which generates the coherent radiation. It is emitted in a quantum mechanical system during a transition between two energy levels of molecules in a gas of dimension small compared to a wavelength.
Claudio Pellegrini is an Italian/American physicist known for his pioneering work on X-ray free electron lasers and collective effects in relativistic particle beams.
A gravity laser, also sometimes referred to as a Gaser, Graser, or Glaser, is a hypothetical device for stimulated emission of coherent gravitational radiation or gravitons, much in the same way that a standard laser produces coherent electromagnetic radiation.
Avraham (Avi) Gover is an Israeli professor of Electrical Engineering in the Physical Electronics Department of the Engineering Faculty at Tel Aviv University, specializing in Quantum Electronics and FEL Physics. Gover is also the head of the Israeli Center for Radiation Sources and Applications in Ariel. In 2005, he was awarded the international FEL prize "in recognition for his outstanding contributions to Free Electron Laser science and technology".
Sandra Gail Biedron is an American physicist who is a professor in Electrical & Computer Engineering and Mechanical Engineering at the University of New Mexico, where in 2021 she mentors nine graduate students and two post-doctoral researchers. Her research includes the development, control, operation and use of laser and particle accelerator systems. She is also Chief Scientist of Element Aero, a consulting and R&D company incorporated in 2002. She was elected Fellow of the American Physical Society in 2013.
References
- ↑ Kondratenko, A. M.; Saldin, E. L. (1980). "Generation of coherent radiation by a relativistic electron beam in an undulator". Particle Accelerators. 10: 207–216.
- ↑ Milton, S. V. (2001). "Exponential Gain and Saturation of a Self-Amplified Spontaneous Emission Free-Electron Laser". Science. 292 (5524): 2037–2041. Bibcode:2001Sci...292.2037M. doi:10.1126/science.1059955. ISSN 0036-8075. PMID 11358995.
- ↑ Zhirong, H.; Kwang-Je, K. (2007). "Review of x-ray free-electron laser theory". Physical Review Special Topics - Accelerators and Beams. 10 (3): 034801. Bibcode:2007PhRvS..10c4801H. doi: 10.1103/PhysRevSTAB.10.034801 .
- ↑ Emma, P. (2010). "First lasing and operation of an ångstrom-wavelength free-electron laser". Nature Photonics. 4 (9): 641–647. Bibcode:2010NaPho...4..641E. doi:10.1038/NPHOTON.2010.176.
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