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2010, Hyperfine Interactions
Proposed as satellite-based weapons during the 1980s, X-ray lasing was for a long time only achieved with enormous amounts of pump energy in either nuclear explosions or at kilojoule-class laser installations. During the last few years a tremendous development was achieved, most visible in the realisation of the FEL lasers at DESY and SLAC. As important for a wider applicability is the enormous reduction in pump energy for laser pumped plasma X-ray lasers, which now brings such devices into the range of applications for diagnostics and spectroscopy even in smaller laboratories. Main developments were the transient excitation scheme and the optimized pumping concepts. This paper concentrates on developments at the GSI Helmholtzcenter at Darmstadt aiming towards reliable X-ray laser sources in the range from 50 to several 100 eV. The main driving forces for the laser development
Laser and Particle Beams, 2002
Recent experiments undertaken at the Rutherford Appleton Laboratory to produce X-ray lasing over the 5–30 nm wavelength range are reviewed. The efficiency of lasing is optimized when the main pumping pulse interacts with a preformed plasma. Experiments using double 75-ps pulses and picosecond pulses superimposed on 300-ps background pulses are described. The use of travelling wave pumping with the approximately picosecond pulse experiments is necessary as the gain duration becomes comparable to the time for the X-ray laser pulse to propagate along the target length. Results from a model taking account of laser saturation and deviations from the speed of light c of the travelling wave and X-ray laser group velocity are presented. We show that X-ray laser pulses as short as 2–3 ps can be produced with optical pumping pulses of ≈1-ps.
Laser and Particle Beams, 2007
Intense and stable laser operation with Ni-like Zr and Ag was demonstrated at pump energies between 2 J and 5 J energy from the PHELIX pre-amplifier section. A novel single mirror focusing scheme for the TCE x-ray laser~XRL! has been successfully implemented by the LIXAM0MBI0GSI collaboration under different pump geometries. This shows potential for an extension to shorter XRL wavelength. Generation of high quality XRL beams for XRL spectroscopy of highly charged ions is an important issue within the scientific program of PHELIX. Long range perspective is the study of nuclear properties of radioactive isotopes within the FAIR project.
Proceedings of LEOS'94, 1994
Laser and Particle Beams, 1995
An experimental investigation on X-ray emission from laser-produced plasmas is presented and the properties of such an emission of interest for application purposes are examined. Plasmas were generated by focusing 1 μm, 3 ns Nd laser pulses onto Al and Cu targets at an intensity of 1013 W/cm2. The temporal evolution of the emission and its spectral features were investigated by using an X-ray streak-camera and an X-ray photodiode. In the case of Cu targets, the analysis of the emission showed two spectral components. The main component was centered at ≈ 1.2 keV and a minor component, whose intensity was measured to be 10-3 of the previous component, was observed at ≈7 keV. The X-ray conversion efficiency, in the investigated spectral region, was measured to be 1% for Cu targets and 0.3% for Al targets.
Proceedings of SPIE - The International Society for Optical Engineering, 2009
The PHELIX laser at the GSI Helmholtz center for heavy-ion research is dedicated to provide high energy, ultra-intense laser pulses for experiments in combination with energetic ion beams. Development of x-ray lasers is targeting a number of applications in this context, including x-ray laser spectroscopy of highly-charged ions, and Thomson scattering diagnostics of heavy-ion driven plasmas. Recent developments centered on the application of a novel double-pulse pumping scheme under GRIP-like, non-normal incidence geometry for both the pre-and the main pulse for transient pumped Ni-like lasers. This scheme considerably simplifies the set-up, and provides a very stable pumping situation even at low pump energies close to the lasing threshold. The technique was scaled to pulse energies above 100 J for the pumping of shorter wavelength x-ray lasers. In addition, a slightly tunable high-harmonic source using a split-off beam from the Nd:Glass pre-amplifier of PHELIX was developed as a seeding source.
Damage to VUV, EUV, and X-ray Optics IV; and EUV and X-ray Optics: Synergy between Laboratory and Space III, 2013
The aim of this work is to design and build a source for a range of applications, with optimized multilayer structures in order to use the source output as efficiently as possible. The source is built around a Nd:YAG laser with fundamental wavelength 1064 nm, frequency doubled 532 nm (green) and tripled 355 nm, with a pulse length of about 800 ps and a repetition rate up to 50 Hz. The target material is Mylar (C 10 H 8 O 4 ) tape, which is cheap, readily available and has many benefits as explained in this article. A versatile cubic target chamber and a set of computer controlled stage motors are used to allow positioning of the X-ray emission point. A range of measures is used to protect delicate components and optics, including a glass slide between the focusing lens and the target to prevent the lens being coated with debris. A low pressure gas (typically 3-6 mbar) is used inside the chamber as collision of atomic size debris particles with gas molecules reduces their kinetic energy and consequently their adhesion to the surrounding surfaces. The gas used is typically helium or nitrogen, the latter also acting as a spectral filter. Finally, the chamber is continually pumped to ensure that more than 70% of the debris particles are pumped out of the chamber.
Atomic processes in plasmas, 1998
This is a preprint of a paper intended for publication in a journal or proceedings. Since changes may be made before publication, this preprint is made available with the understanding that it will not be cited or reproduced without the permission of the author.
Applied Physics B, 2017
and technology, like nano-imaging including 3-dimensional molecular imaging, dense plasma diagnostics, lithography, holography, study of radiation-induced damage in biomolecules . In fact, if such sources are available in a compact table-top form in the laboratories, several new applications may come up in future. Pumping through fast capillary discharge is one of the promising techniques which has great potential for making table-top X-ray laser systems. First time, this technique was utilized to observe soft X-ray amplification in C VI Balmer-α transition at 18.2 nm driven by recombination pumping . However, this was a kind of ablative discharge where the gain medium of carbon plasma was formed by the ablation of capillary wall made of carbon-containing material. Such a laser had a small gain-length product limited by the nonuniformity of the plasma column beyond few millimetres. The journey of fast capillary discharge scheme towards X-ray laser was boosted further with the first experimental demonstration of soft X-ray lasing at 46.9 nm based on collisional excitation pumping in Ne-like Ar by Rocca et al. . Here, the gain medium was formed by the discharge through gas-filled capillary and not by the ablative discharge. The axial uniformity could be obtained over a larger plasma length inside the capillary due to the introduction of a small current (few amperes) pre-pulse a few microseconds before the main pulse. This helped in getting larger gain-length product and as a result, the scheme progressed well with the development of soft X-ray laser working even in the saturation regime . This was further extended for making very compact X-ray laser system running at few hertz repetitive rate . Subsequently, various groups across the globe also reported successful demonstration of this X-ray lasing and contributed significantly in this area of research . Apart from argon gas, the scheme was successfully utilized to demonstrate soft X-ray lasing
Review Scientific Instruments 72, 3983-3987 (2001), 2001
""We have designed and tested a one-meter long X-ray diode based on innovative plasma-cathodes, which exploit commercial spark-plugs as electron emitters. Based on the results of a numerical study, we optimized both diode geometry (e.g., the angle between anode and cathode surfaces, the thickness of Al window) and electrical circuitry (e.g., the capacitance in series to each spark-plug, the peak voltage of the anode) of our X-ray generator. The overall result is a simple and efficient circuitry, giving a total diode current in excess of 2.1 kA with a breakdown voltage of 70 kV, which generates a 50-ns-risetime X-ray pulse with a spatially averaged dosage of up to 6 10-4 Gy when using a Pb-wrapped anode. The double-diode X-ray generator was operated for 1.5 106 shots at a repetition rate of up to 30 Hz, and the lifetime test was interrupted without any fault. During the lifetime test, it was not necessary to adjust any working parameter. At the end of the lifetime test, the X-ray emission uniformity was better than 80% along the longitudinal axis. This X-ray generator has a lifetime, reliability and cost fitting the requirements of industrial users. Among the broad range of potential applications, this X-ray generator is particularly suitable to ionize discharge pumped gas lasers, like TEA CO2 and excimer lasers, including those operated by X-ray triggered discharges.""
Laser and Particle Beams, 2000
A high brightness laser-plasma X-ray source has been set-up and is presently available at IFAM. A wide range of diagnostics has been set up to monitor the properties of the X-ray radiation and to control the main parameters including photon energy, flux intensity, and pulse duration. A beam extractor enables access to the X-ray radiation at atmospheric pressure. A simple, easy-to-use projection microscope has been built which is capable of single-shot micron resolution imaging with digital acquisition. Preliminary biomedical experiments show that the X-ray doses available on a single laser shot exposure of our source fully meet the conditions required for an important class of biological experiments based on X-ray induced DNA damage providing an ideal alternative to the long time exposures needed with X-ray tubes.
Applied Optics, 2003
A two-beam chirped-pulse-amplification Nd:glass laser system dedicated to x-ray laser research is described. Each beam provides an output energy of 20 J with a typical pulse duration of 1.3 ps. A prepulse of variable duration is generated by use of a novel, to our knowledge, optical system. A reflection optical system, comprised of an off-axis parabolic mirror and a spherical mirror, produces a line focus with 6-mm length and 15-m width without chromatic aberration. By use of this pumping laser system, the nickel-like silver x-ray laser at a wavelength of 13.9 nm has been demonstrated.
Journal of Quantitative Spectroscopy and Radiative Transfer, 2006
High harmonic amplification is shown in an optical-field ionized X-ray laser. The 4d-4p X-ray line of Kr 8+ at 32.8 nm, which has a close match to the 25th harmonic of the infrared laser, was amplified up to 200 times. The energy-extraction regime was also achieved, which depended on the level of seeding. This second-generation X-ray laser is fully polarized, has low divergence and shows a high degree of coherence. The duration is also expected to be short, fulfilling the requirements for an ultra-intense tabletop X-ray laser. Conditions for higher energy output are also suggested. r Researchers from a wide range of fields, for example, plasmas and high energy density physics, material science, femto-chemistry and biology, have recently turned their attention to short-pulse ultrabright X-ray lasers as a major tool for scientific advances. Such interest has recently been spurred by the success of free electron laser (FEL) sources as potential ultra-bright sources in the XUV (4-60 nm).
Physical Review Letters, 1974
C 0 2 Laser (K. Manes) . C 0 2 Target Chamber (S. Glaros) . X-Ray Measurements (W. Slivinsky) . References .
2015
This article describes the study of rapidly evolving hot dense plasma, created by focusing high intensity laser pulses on to solid target surface, carried out at RRCAT, Indore. The basic concept of intense laser matter interaction and x-ray emission from plasma is briefly presented. The study of ionization dynamics of plasma by measuring x-ray yield of different ionic line radiation from the plasma produced by laser pulses from nanoseconds to femtosecond duration is discussed. The experimental signature of radiation transport in plasma is observed from the measurement of x-ray yield in keV spectral region from the mix-Z target. The transient conditions in plasma created by intense ultra-short laser were identified by simultaneous measurements of the inner-shell and the ionic line radiation. The generation and optimization of monochromatic K-x-ray source by intense femtosecond laser pulse were performed. A setup for ultrashort x-ray probe and pump technique developed to study the time resolved x-ray diffraction from a sample undergoing laser generated shock is described. The challenges and future outlook in this field is summarized.
Applied Physics B Photophysics and Laser Chemistry, 1990
Recent Ne-and Ni-like X-ray laser experiments carried out at the Centre d'Etudes de Limeil-Valenton (CEL-V) are reviewed. A variety of experiments in Ne-like X-ray lasers were performed; here we discuss measurements of soft X-ray amplification in Ge (Z= 32) and Sr (Z = 38) plasmas. In Ge plasmas produced by 0.53-gin laser light at an irradiance of 6.0 x 1013 W/cm 2, gains between 2.2-2.5 cm-1 on the 232.2 and 236.2 A J=2-1 lines and a gain of 1.0 cm-1 on the 196.1 A J =0-1 line were measured. In addition, gains of 4.4 cm-i and 4.0 cm-~ have been demonstrated on the J = 2-1 transitions at 164.1 and 166.5 A in Nelike Sr at laser intensities of 1.3 x 1014 W/cm 2. The effects of pumping the Ne-like Se X-ray laser with 0.35-gm laser light have also been investigated; the Se lasing spectra is similar to that obtained with 0.53-gm light. Experiments have also been carried out to optimize the gain of the 50.3 A Ni-like Yb (Z = 70) J = 0-1 line. For Yb, no significant increase in gain over that previously reported was seen, but the time history of the Ni-like Yb X-ray laser was measured for the first time. Finally, attempts to extrapolate the Ni-like results to shorter wavelength were made using Ta (Z=73), W (Z=74), and Re (Z=75). No definitive observation of the Ni-like J = 0.1 lasing lines was made in these experiments.
Review of Scientific Instruments, 1995
Collisionally pumped soft x-ray lasers now operate over a wavelength range extending from 35 to 300 A. These well-characterized sources have high peak brightness (GeV blackbody temperature) and narrow bandwidth making them ideal for x-ray imaging and interferometry. We will describe experiments which have used the yttrium neon-like x-ray laser operating at 155 A to probe plasmas at electron densities exceeding 4X 10" cm-s . The short pulse duration of this x-ray laser (-150 ps) has made it possible to image directly driven thin foils with l-2 pm spatial resolution. Advances in multilayer mirrors and beam splitters have now also made it possible to develop x-ray laser interferometers. We will describe initial experiments to probe plasmas relevant to ICF using x-ray laser interferometry. The progress in the development of short pulse x-ray lasers (-30 ps) which are ultimately necessary to extend x-ray laser diagnostic techniques to higher densities will also be presented. 8 1995 American Institute of Physics. Rev. Sci. Instrum. 66 (I), January 1995 QQ34-6746/95/66(1)/574lS/$6.QQ
X-Ray Lasers 2016, 2018
When short wavelength extreme ultraviolet (EUV) and x-ray laser radiation is focused onto solid targets, narrow deep features are ablated and a dense, low temperature plasma is formed. We examine the radiation dominated plasma formed by 46.9 nm laser radiation focused onto solids and show that ionization can be significantly modified by electron degeneracy effects. Some experimental and theoretical considerations for investigating the interaction of capillary discharge lasers operating at 46.9 nm with solid and gas targets are presented.
High Energy Density Physics, 2019
A standard technique for generating a burst of hard x rays (above 30 keV) is to use ultra high intensity lasers incident on a target. The strong laser field causes rapid electron oscillations which then generate hard x rays via bremsstrahlung. We have demonstrated a new technique for optimizing the conversion efficiency of laser light to hard x rays at moderate Iλ 2 (mid 10 13 W/cm 2 .µm 2 ) assuming that the two plasmon decay plasma instability is the predominant acceleration mechanism. In this scheme, electrons are not directly accelerated by the laser field but by electron plasma waves. Experiments at the National Ignition Facility show the effect of a pre-pulse on the hard x ray spectrum and conversion efficiency. Different experimental configurations are investigated to optimize the conversion efficiency using various pre-pulse levels as well as different target designs (gold vs. silver, varying target thickness, presence of an ablator layer of CH). The conversion efficiency of laser energy into photon above 30 keV for a 100 ps short pulse scales as ∼ I 1.23 for laser intensity ranging from 1 × 10 16 to 1 × 10 17 W/cm 2 at 3ω for high Z target. A 1-ns-long pre-pulse pre-seeding an 88-ps Gaussian laser pulse coupled with a CH-coated thin Au target led the highest conversion efficiency above 30 keV of ∼ 3 10 4 × .
Journal de Physique Lettres, 1981
2014 Une émission laser de longue durée (200 ns) et de rendement élevé a été obtenue à 3 080 Å à partir de l'excimère XeCl* à la suite de l'excitation de mélanges Ne/Xe/HCl à température ambiante et à très basse température par une décharge en régime d'avalanche assistée par un faisceau d'électrons et de rayons X. L'énergie apportée au milieu actif par la décharge était de plusieurs ordres de grandeur supérieure à celle apportée par le faisceau de préionisation. L'énergie spécifique laser maximale obtenue était de 3 J/1 à température ambiante pour une longueur de gain de 16 cm et une énergie apportée au milieu actif par la décharge égale à 150 J/l. Abstract. 2014 Long pulse (200 ns) XeCl excimer laser emission (03BB = 3 080 Å), has been obtained when Ne/Xe/HCl mixtures are excited by an electron beam and X-rays assisted discharge either at room temperature or at very low temperature. Absorbed discharge energy is several orders of magnitude higher than the absorbed beam energy. Maximum specific laser energy is 3 J/l at room temperature for a 16 cm gain length and an absorbed discharge energy of 150 J/1.
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