X-ray laser

Last updated

An X-ray laser can be created by several methods either in hot, dense plasmas or as a free-electron laser in an accelerator. This article describes the x-ray lasers in plasmas, only.

Contents

The plasma x-ray lasers rely on stimulated emission to generate or amplify coherent, directional, high-brightness electromagnetic radiation in the near X-ray or extreme ultraviolet region of the spectrum, that is, usually from ~3 nanometers to several tens of nanometers (nm) wavelength.

Because of high gain in the lasing medium and short upper-state lifetimes (1100  ps), X-ray lasers usually operate without mirrors; the beam of X-rays is generated by a single pass through the gain medium. The emitted radiation, based on amplified spontaneous emission, has relatively low spatial coherence. The line is mostly Doppler broadened, which depends on the ions' temperature.

As the common visible-light laser transitions between electronic or vibrational states correspond to energies up to only about 10 eV, different active media are needed for X-ray lasers.

Between 1978 and 1988 in Project Excalibur the U.S. military attempted to develop a nuclear explosion-pumped X-ray laser for ballistic missile defense as part of the "Star Wars" Strategic Defense Initiative (SDI). [1]

Active media

The most often used media include highly ionized plasmas, created in a capillary discharge or when a linearly focused optical pulse hits a solid target. In accordance with the Saha ionization equation, the most stable electron configurations are neon-like with 10 electrons remaining and nickel-like with 28 electrons remaining. The electron transitions in highly ionized plasmas usually correspond to energies on the order of hundreds of electron volts (eV).

The vacuum chambers at the PALS laboratory in Prague, where a 1 kJ pulse creates plasma for X-ray generation Prague asterix laser system-interaction chamber.jpeg
The vacuum chambers at the PALS laboratory in Prague, where a 1 kJ pulse creates plasma for X-ray generation

Common methods for creating plasma X-ray lasers include:

An alternative amplifying medium is the relativistic electron beam in a free-electron laser, which, strictly speaking, uses stimulated Compton scattering instead of stimulated emission.

Other approaches to optically induced coherent X-ray generation are:

Applications

Applications of coherent X-ray radiation include coherent diffraction imaging, research into dense plasmas (not transparent to visible radiation), X-ray microscopy, phase-resolved medical imaging, material surface research, and weaponry.

A soft x-ray laser can perform ablative laser propulsion.

See also

Related Research Articles

<span class="mw-page-title-main">Laser</span> Device which emits light via optical amplification

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 anacronym that originated as an acronym for light amplification by stimulated emission of radiation. The first laser was built in 1960 by Theodore Maiman at Hughes Research Laboratories, based on theoretical work by Charles H. Townes and Arthur Leonard Schawlow.

<span class="mw-page-title-main">Maser</span> Device for producing coherent EM waves in the sub-visible spectrum

A maser is a device that produces coherent electromagnetic waves (microwaves), through amplification by stimulated emission. The term is an acronym for microwave amplification by stimulated emission of radiation. First suggested by Joseph Weber, The first maser was built by Charles H. Townes, James P. Gordon, and Herbert J. Zeiger at Columbia University in 1953. Townes, Nikolay Basov and Alexander Prokhorov were awarded the 1964 Nobel Prize in Physics for theoretical work leading to the maser. Masers are also used as the timekeeping device in atomic clocks, and as extremely low-noise microwave amplifiers in radio telescopes and deep-space spacecraft communication ground stations.

<span class="mw-page-title-main">Free-electron laser</span> Laser using electron beam in vacuum as gain medium

A free-electron laser (FEL) is a fourth generation light source producing extremely brilliant and short pulses of radiation. An FEL functions much as a laser but employs relativistic electrons as a gain medium instead of using stimulated emission from atomic or molecular excitations. In an FEL, a bunch of electrons passes through a magnetic structure called an undulator or wiggler to generate radiation, which re-interacts with the electrons to make them emit coherently, exponentially increasing its intensity.

<span class="mw-page-title-main">Laser pumping</span> Powering mechanism for lasers

Laser pumping is the act of energy transfer from an external source into the gain medium of a laser. The energy is absorbed in the medium, producing excited states in its atoms. When for a period of time the number of particles in one excited state exceeds the number of particles in the ground state or a less-excited state, population inversion is achieved. In this condition, the mechanism of stimulated emission can take place and the medium can act as a laser or an optical amplifier. The pump power must be higher than the lasing threshold of the laser.

This is a list of acronyms and other initialisms used in laser physics and laser applications.

<span class="mw-page-title-main">Extreme ultraviolet</span> Ultraviolet light with a wavelength of 10–121nm

Extreme ultraviolet radiation or high-energy ultraviolet radiation is electromagnetic radiation in the part of the electromagnetic spectrum spanning wavelengths shorter that the hydrogen Lyman-alpha line from 121 nm down to the X-ray band of 10 nm, and therefore having photons with energies from 10.26 eV up to 124.24 eV. EUV is naturally generated by the solar corona and artificially by plasma, high harmonic generation sources and synchrotron light sources. Since UVC extends to 100 nm, there is some overlap in the terms.

Amplified spontaneous emission (ASE) or superluminescence is light, produced by spontaneous emission, that has been optically amplified by the process of stimulated emission in a gain medium. It is inherent in the field of random lasers.

Ultrafast laser spectroscopy is a category of spectroscopic techniques using ultrashort pulse lasers for the study of dynamics on extremely short time scales. Different methods are used to examine the dynamics of charge carriers, atoms, and molecules. Many different procedures have been developed spanning different time scales and photon energy ranges; some common methods are listed below.

<span class="mw-page-title-main">Sound amplification by stimulated emission of radiation</span>

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.

<span class="mw-page-title-main">Gurgen Askaryan</span> Soviet-Armenian physicist

Gurgen Ashotovich Askaryan was a prominent Soviet - Armenian physicist, famous for his discovery of the self-focusing of light, pioneering studies of light-matter interactions, and the discovery and investigation of the interaction of high-energy particles with condensed matter.

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.

Margaret Mary Murnane NAS AAA&S is an Irish physicist, who served as a distinguished professor of Physics at the University of Colorado at Boulder, having moved there in 1999, with past positions at the University of Michigan and Washington State University. She is currently Director of the STROBE NSF Science and Technology Center and is among the foremost active researchers in laser science and technology. Her interests and research contributions span topics including atomic, molecular, and optical physics, nanoscience, laser technology, materials and chemical dynamics, plasma physics, and imaging science. Her work has earned her multiple awards including the MacArthur Fellowship award in 2000, the Frederic Ives Medal/Quinn Prize in 2017, the highest award of The Optical Society, and the 2021 Benjamin Franklin Medal in Physics.

<span class="mw-page-title-main">European XFEL</span>

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.

<span class="mw-page-title-main">Philip H. Bucksbaum</span>

Philip H. Bucksbaum is an American atomic physicist, the Marguerite Blake Wilbur Professor in Natural Science in the Departments of Physics, Applied Physics, and Photon Science at Stanford University and the SLAC National Accelerator Laboratory. He also directs the Stanford PULSE Institute.

<span class="mw-page-title-main">Claudio Pellegrini</span>

Claudio Pellegrini is an Italian/American physics and emeritus professor at University of California, Los Angeles (UCLA), known for his pioneering work on X-ray free electron lasers and collective effects in relativistic particle beams.

A gamma-ray laser, or graser, is a hypothetical device that would produce coherent gamma rays, just as an ordinary laser produces coherent rays of visible light. Potential applications for gamma-ray lasers include medical imaging, spacecraft propulsion, and cancer treatment.

High Harmonic Generation (HHG) is a non-perturbative and extremely nonlinear optical process taking place when a highly intense ultrashort laser pulse undergoes an interaction with a nonlinear media. A typical high order harmonic spectra contains frequency combs separated by twice the laser frequency. HHG is an excellent table top source of highly coherent extreme ultraviolet and soft X-ray laser pulses.

A plasma mirror is an optical mechanism which can be used to specularly reflect high intensity ultrafast laser beams where nonlinear optical effects prevent the usage of conventional mirrors and to improve laser temporal contrast. If a sufficient intensity is reached, a laser beam incident on a substrate will cause the substrate to ionize and the resulting plasma will reflect the incoming beam with the qualities of an ordinary mirror. A single plasma mirror can be used only one time, as during the interaction the beam ionizes the subtrate and destroys it.

<span class="mw-page-title-main">Randy Bartels</span>

Randy Alan Bartels is an American investigator at the Morgridge Institute for Research and a professor of Biomedical Engineering at the University of Wisconsin–Madison. He has been awarded the Adolph Lomb Medal from the Optical Society of America, a National Science Foundation CAREER award, a Sloan Research Fellowship in physics, an Office of Naval Research Young Investigator Award, a Beckman Young Investigator Award, and a Presidential Early Career Award for Science and Engineering (PECASE). In 2020 and 2022, he received support from the Chan Zuckerberg Initiative to develop microscope technologies for imaging tissues and cells. 

References

  1. www.darpa.mil https://www.darpa.mil/program/excalibur . Retrieved 2023-11-02.{{cite web}}: Missing or empty |title= (help)
  2. Rocca, J. J.; Shlyaptsev, V.; Tomasel, F. G.; Cortázar, O. D.; Hartshorn, D.; Chilla, J. L. A. (1994-10-17). "Demonstration of a Discharge Pumped Table-Top Soft-X-Ray Laser". Physical Review Letters. 73 (16): 2192–2195. doi:10.1103/PhysRevLett.73.2192.
  3. Kuba, Jaroslav. Experimental and Theoretical Study of X-ray Lasers Pumped by an Ultra-Short Laser Pulse: Transient Pumping of Ni-like Ag Ions. Université de Paris, France 2001.
  4. Chang, Zenghu; Rundquist, Andy; Wang, Haiwen; Murnane, Margaret M.; Kapteyn, Henry C. (20 October 1997). "Generation of Coherent Soft X Rays at 2.7 nm Using High Harmonics". Physical Review Letters. 79 (16): 2967. Bibcode:1997PhRvL..79.2967C. doi:10.1103/PhysRevLett.79.2967.
  5. Popmintchev1, Tenio; Chen, Ming-Chang; Popmintchev, Dimitar; Arpin, Paul; Brown, Susannah; Ališauskas, Skirmantas; Andriukaitis, Giedrius; Balčiunas, Tadas; Mücke, Oliver D.; Pugzlys, Audrius; Baltuška, Andrius; Shim, Bonggu; Schrauth, Samuel E.; Gaeta, Alexander; Hernández-García, Carlos; Plaja, Luis; Becker, Andreas; Jaron-Becker, Agnieszka; Murnane, Margaret M.; Kapteyn, Henry C. (8 June 2012). "Bright Coherent Ultrahigh Harmonics in the keV X-ray Regime from Mid-Infrared Femtosecond Lasers". Science. 336 (6086): 1287–1291. Bibcode:2012Sci...336.1287P. doi:10.1126/science.1218497. hdl: 10366/147089 . PMID   22679093. S2CID   24628513.{{cite journal}}: CS1 maint: numeric names: authors list (link)
  6. Popmintchev, D.; Hernández-García, C.; Dollar, F.; Mancuso, C. A.; Peng, P.-C.; Barwick, B.; Gorman, T. T.; Alonso-Mori, R.; Ališauskas, S.; Andriukaitis, G.; Baltuška, A.; Bostedt, C.; Chen, M.-C.; Dakovski, G. L.; Durfee, C. G.; Eckert, S.; Fan, T.-M.; Ferguson, W. R.; Frischkorn, C. G.; et al. (2015). "Ultraviolet surprise: Efficient soft x-ray high-harmonic generation in multiply ionized plasmas". Science . 350 (6265): 1225–1231. Bibcode:2015Sci...350.1225P. doi:10.1126/science.aac9755. hdl: 10366/147088 . PMID   26785483.
  7. Whittum, David H.; Sessler, Andrew M.; Dawson, John M. (1990). "Ion-channel laser". Physical Review Letters. 64 (21): 2511–2514. Bibcode:1990PhRvL..64.2511W. doi:10.1103/PhysRevLett.64.2511. PMID   10041731.