Development of a Pumping Laser System for X-ray Laser Research

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 E, 2010

Soft x-ray lasers pumped in the grazing incidence geometry show strongly reduced energetic needs but hardly changed conversion efficiency between the pump energy and the output short-wavelength radiation. Numerical analysis presented in the paper concerns with performance of a Ni-like Ag soft-x-ray laser pumped by a triple-pulse structure in the grazing incidence geometry as a function of the puming conditions. It was found that a weak precursor preceding the main preforming and heating pulses by a few nanoseconds is crucial for the energy deposition. Its presence enables in different arrangements a reasonable reduction in the pump energy and relaxation of the steep density gradients as well as a control over partition of the deposited energy. As a consequence, it was concluded that a well energetically balanced three-or multipulse composition seems to be a reasonable way to achieve performance improvement.

Hyperfine Interactions, 2010

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

Almost everyone probably knows that the police use laser when they measure speed. At least many drivers that have exceeded the speed limit know about it, but how many know that you also use laser several times in a day? You will find its use in cd players and in laser printers. You often find laser in action movies where the hero has to escape the laser beams when he's trying to solve a thrilling problem. The power contained in laser is both fascinating and frightening. There is nothing magical about a laser. It can be thought of as just another type of light source. It certainly has many unique properties that make it as a special source of light, but these properties can be understood without the knowledge of sophisticated mathematical techniques or complex ideas .The concepts, as they are developed, will be applied to all classes of laser frequencies and laser materials, so that we will develop a sense of broad field of lasers. Furthermore, we may also understand that how a l...

IEEE Journal of Selected Topics in Quantum Electronics, 1999

Recent realization of saturated X-ray lasers (XRL's) has considerably extended the range of optical properties of soft X-ray sources toward high brightness and large coherence length. Consequently, new results may be expected from studies previously experienced with traditional sources such as synchrotron radiation. On the other hand, XRL's open new fields of research owing to their high brightness. In this paper, we present some of the first experiments utilizing XRL sources.

Optics Communications, 1981

High conversion efficiency of laser energy into X-rays from a laser irradiated target is of great interest for a variety of dynamical (pulsed) studies, e.g.: radiography of laser-imploded targets, structure determination by diffraction and absorption fiiestructure, and X-ray laser pumping. We report here on a frequency tripled Nd : glass laser used to irradiate targets of various materials at-5 X lOI4 W/cm*. We find conversion efficiencies of between 1% and 0.1% (with respect to the incident laser energy) for individual X-ray lines between 1.8 and 7.8 keV. These efficiencies are more than an order of magnitude higher than those achieved with 1.06 r.trn lasers.

Journal of the Optical Society of America B, 2003

Recent high-temporal-resolution nickellike x-ray laser experiments have yielded important insights into the output characteristics of picosecond-pumped x-ray lasers. However, current experimental observations do not fully explain the plasma dynamics, which is critical to gain generation within the x-ray laser medium. A numerical study of the nickellike silver x-ray laser has therefore been undertaken to complement our experimental results in an attempt to further our understanding of the processes at work in yielding the observed x-ray laser output. High gain coefficients existing with picosecond lifetimes are predicted, which is consistent with the short x-ray laser durations experimentally observed. The late onset of the continuum emission relative to the temporal peak of the x-ray laser output is explained as a sign of high electron density evolution near the target surface.

Journal of the Optical Society of America B, 2000

We report what is to our knowledge the first demonstration of a transient x-ray laser pumped by a 350-fs pulse in a traveling-wave irradiation geometry. For a 500-fs pump pulse the traveling-wave irradiation was found to have a strong effect on enhancing the Ni-like silver 4d-4p lasing emission at 13.9 nm. The signal enhancement was significantly less when the pulse duration was lengthened to 1.7 ps. The experimental observations are well reproduced by a simple model when the duration of gain is taken of the order of 15-20 ps. For the 500-fs pulse a gain coefficient of 14.5 cm Ϫ1 was measured for plasma lengths up to 7 mm. Refraction of the amplified photons is believed to be the main cause of the limitation of the effective amplification length.

Soft X-Ray Lasers and Applications VIII, 2009

This paper gives an overview of recent progress of laser-driven plasma x-ray lasers in Japan Atomic Energy Agency (JAEA). Fully spatial coherent plasma x-ray laser (XRL) at 13.9 nm with 0.1 Hz repetition rate has been developed using new driver laser system TOPAZ, and the succeeding optimization of the pumping condition has realized more efficient generation of the coherent x-ray pulse. The 0.1 Hz XRL is now routinely used in the wide variety of the application experiments: The highlights of these applications are the study of fluctuation in the atomic structure of ferroelectric substances under the phase transition using the double XRL probe beam technique and the construction of new x-ray laser interferometer to observe nano-scale dynamics of materials.

Physical Review A, 2005

This paper reports on the modeling of the Ni-like silver transient x-ray laser at the wavelength of 13.9 nm. Time-dependent populations and gain are calculated consistently with the output intensity. Two-dimensional refraction, i.e., in the direction of the driving laser and parallel to the slab target surface, is modeled by a ray trace code which is a postprocessor of a hydrodynamic code. Temperatures and electron-density variations are given by the hydrocode. Our calculations show that interaction of the x-ray laser field with the amplifying medium, and refraction, affect the output intensity and reduce the gain values by a large factor: from many hundreds per cm, as predicted by collisional-radiative models ignoring the above interaction, to one hundred per cm, at most.

2009

Applied Sciences, 2013

Extensive modeling of the seeding of plasma-based soft X-ray lasers is reported in this article. Seminal experiments on amplification in plasmas created from solids have been studied in detail and explained. Using a transient collisional excitation scheme, we show that a 18 µJ, 80 fs fully coherent pulse is achievable by using plasmas pumped by a compact 10 Hz laser. We demonstrate that direct seeding of plasmas created by nanosecond lasers is not efficient. Therefore, we propose and fully study the transposition to soft X-rays of the Chirped Pulse Amplification (CPA) technique. Soft X-ray pulses with energy of 6 mJ and 200 fs duration are reachable by seeding plasmas pumped by compact 100 J, sub-ns, 1 shot/min lasers. These soft X-ray lasers would reach GW power, corresponding to an increase of 100 times as compared to the highest peak power achievable nowadays in the soft X-ray region (30 eV-1 keV). X-ray CPA is opening new horizon for soft x-ray ultra-intense sources.

Comptes Rendus de l'Académie des Sciences - Series IV - Physics, 2000

We have demonstrated saturated output on several nickel-like ion X-ray lasers ranging from niobium to silver by using a psec, high-power, chirped-pulse-amplification, tabletop laser. These results have been achieved at wavelengths from 20.3 to 13.9 nm on the Ni-like 3d 9 4d 1 S0 → 3d 9 4p 1 P1 laser line using a total of 5 to 7 J of energy in a traveling wave excitation scheme. Strong amplification is also observed for Ni-like Sn at 11.9 nm. Gain of 41 cm −1 , gain-length product of 18, and output energy of 12 µJ are measured for the Ni-like Pd line at 14.7 nm. For Ni-like Mo, experiments are done using multilayer mirrors to obtain two-dimensional images of the output aperture of the laser and to measure the total laser energy as a function of various parameters such as the delay between the short and long pulses and the energy of the two pulses. For Mo we measure an output energy of 2 µJ and a gain-length product of 16.6. To model the Mo experiments, the LASNEX code is used to calculate the hydrodynamic evolution of the plasma and provide the temperatures and densities to the XRASER code, which then does the kinetics calculations to determine the gain. The temporal and spatial evolution of the plasma is studied both with and without radiation transport included for the 4f and 4p → 3d Ni-like Mo resonance lines. High gains are predicted and observed for both the 3d 9 4d 1 S0 → 3d 9 4p 1 P1 laser line at 18.9 nm and the 3d 9 4f 1 P1 → 3d 9 4d 1 P1 photopumped line at 22.6 nm. © 2000 Académie des sciences/Éditions scientifiques et médicales Elsevier SAS X-ray laser Revue de la recherche sur le laser X-UV au Laurence Livermore National Laboratory Résumé. Nous avons mis en évidence une émission saturée pour plusieurs lasers collisionnels X-UV à ions nickeloïdes du niobium à l'argent, pompés par un laser de table picoseconde, de haute puissance, utilisant l'amplification par dérive de fréquence. Ces résultats ont été obtenus aux longueurs d'onde de 20,3 à 13,9 nm sur la raie laser 3d 9 4d 1 S0 → 3d 9 4p 1 P1 de l'ion nickeloïde avec une énergie de pompe de 5 à 7 J délivrée selon le schéma d'excitation en onde progressive. On observe également une forte amplification pour le Sn nickeloïde à 11,9 nm. Pour la raie nickeloïde du palladium à 14,7 nm, nous avons mesuré Note présentée par Guy LAVAL.

Journal of synchrotron radiation, 2014

Developments of X-ray optics for full utilization of diffraction-limited storage rings (DLSRs) are presented. The expected performance of DLSRs is introduced using the design parameters of SPring-8 II. To develop optical elements applicable to manipulation of coherent X-rays, advanced technologies on precise processing and metrology were invented. With propagation-based coherent X-rays at the 1 km beamline of SPring-8, a beryllium window fabricated with the physical-vapour-deposition method was found to have ideal speckle-free properties. The elastic emission machining method was utilized for developing reflective mirrors without distortion of the wavefronts. The method was further applied to production of diffraction-limited focusing mirrors generating the smallest spot size in the sub-10 nm regime. To enable production of ultra-intense nanobeams at DLSRs, a low-vibration cooling system for a high-heat-load monochromator and advanced diagnostic systems to characterize X-ray beam pr...

Le Journal de Physique IV, 2001

We report on a time-resolved study of a Ni-like transient collisional X-ray laser with a resolution as high as 1.9 ps. The FWHM duration of the Ni-like x-ray laser pulse at 13.99 nm Ag J = 0→1 4d-4p line is measured to be as short as ~2 ps at optimum conditions of pump laser irradiation. This is about four times shorter than was estimated in previous experiments. The x-ray laser signal appears in the rising edge of the continuum emission. The x-ray laser duration rises significantly when the short (heating) pulse duration is increased and when doubling the peak-to-peak delay of the two irradiation pulses. It does not change when the short pulse energy is increased. The results presented are the first direct measurements of the temporal profile of the x-ray laser output at a high resolution.