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This paper describes an overview of our recent discovery – clear demonstration that LiF crystals can be efficiently used as a high-performance neutron imaging detector based on optically stimulated luminescence of color centers generated by neutron irradiation. It is shown that the neutron images we have obtained are almost free from granular noise, have a spatial resolution of ${\sim}5.4~{\rm\mu}\text{m}$ and a linear response with a dynamic range of at least $10^{3}$ . The high contrast and good sensitivity of LiF crystals allow us to distinguish two holes with less than 2% transmittance difference. We propose to use such detectors in areas where high spatial resolution with high image gradation resolution is needed, including diagnostics of different plasma sources such as laser and z-pinch produced plasmas.

A new technique for X-ray spectromicroscopy of fast heavy ion radiation during the ion interaction with stopping media is presented using focusing spectrometers with spatial resolution. Spherically bent crystals of quartz and mica with small curvature radii, R=150 mm, and large apertures were used as dispersive elements in experiments on fast Ni ions with energies of 5.9 and 11.2 MeV/u which are being stopped in different media: Ar gas, SiO2-aerogels and solid quartz. Spectrally high (λ/Δλ=1000–3000) and spatially high (up to 10–100 μm) resolved Kα-satellite spectra of Ni projectiles as well as of the ionized stopping media were observed.

Satellite lines caused by radiative transitions from the Rydberg autoionization states of a Li-like Mg X ion in a plasma heated by radiation from a XeCl and a Nd laser are identified for the first time, and their wavelengths are measured precisely. Comparison of the experimental data with the atomic structures calculated by the method of relativistic perturbation theory shows that the accuracy of calculations of the energy of autoionization states is rather high even without the use of any semiempirical corrections and is of the order of 0.06%. The experimentally measured wavelengths can be used for a semiempirical estimate of the value of the leading order of perturbation theory among the orders that were neglected in calculations. It is shown that the simulation of the population kinetics of Rydberg autoionization states of Li-like ions in a dense plasma should take into account all possible channels of dielectronic capture, in particular, from the excited states of a He-like ion. The precision experimental wavelengths obtained for satellites of the Hes and Heγ lines of the Mg XI ion make possible to use these satellites as reference lines in studies of complicated spectra of multielectron ions.

Spectra in the 7.50-8.70???range from highly charged copper ions are analysed, and line identifications are made for the Na-, Ne-, F- and O-like charge states. The spectra are recorded with a spherically bent crystal spectrometer using either a mica or quartz crystal for moderate (?/?? = 3000) and high (?/?? = 8000) energy resolution, respectively. The plasmas from which the spectra are emitted are formed with either a Nd:glass (15?ns pulse) or a XeCl (12?ns pulse) laser. Systematic variations in the observed spectra with pulse energy are studied. Using different laser energies, and defocusing of the laser to reduce the intensity, we create plasmas with different ionization state distributions, which allows us to deconvolve blended lines from different copper ions. Line identifications are made based on relativistic atomic structure calculations that account for configuration interaction in level energies and transition rates. We use full kinetics simulations of ion emissivities, not just calculations of theoretical transition energies, to identify the strong and weak lines in crowded spectral regions. We identify 2p-n? transitions for Ne-like Cu19+ for 4?n?8 and 2s-np transitions for 4?n?6. We offer the first identification of high-n (n?8) Na-like satellites to Ne-like Rydberg resonance lines. The first and second ionization energies for Cu19+ are found, at 1689.02 and 1709.16?eV, respectively, based on our observations.

The X-ray spectral distribution of swift heavy Ti and Ni ions (11 MeV/u) observed inside aerogels (ρ = 0.1 g/cm3) and dense solids (quartz, ρ = 2.23 g/cm3) indicates a strong presence of simultaneous 3–5 charge states with one K-hole. We show that the theoretical analysis can be split into two tasks: first, the treatment of complex autoionizing states together with the originating spectral distribution, and, second, a charge-state distribution model. Involving the generalized line profile function theory, we discuss attempts to couple charge-state distributions.

The wavelengths of the 1snp 1P10-1s2 1S0 transitions in the He-like Mg XI (n = 4-9) and F VIII (n = 4-8) have been measured in laser-produced plasmas. The accuracy of the present measurements (0.4-1.6 mA) is a large improvement over previous results. The Rydberg series is used to determine the ground-state ionization energy of F VIII and Mg XI: Eion (F VIII) = 953.96±0.11 eV, Eion (Mg XI) = 1761.88±0.15 eV. These experimental results are compared with theoretical data calculated by the 1/Z-expansion method and the HFR and MCDF approaches. Fairly good agreement between theory and experiment is observed with a precision up to 5×10-5. Radiative corrections to the 1s2 1S0 state are analysed and compared with experiments. It is found that QED corrections to the ground-state ionization energy are significant at the present level of experimental accuracy.

A portable (200 � 100 � 100 mm 3 ), high-luminosity, spherically bent crystal spectrometer was designed to measure very low emissivity X-ray spectra of different elements with spatial resolution in a wide spectral range (1.2� 19.6 ( A). A large (50 � 15 mm 2 ) open aperture mica spherically bent crystal with R ¼ 150 mm was used as dispersive and focusing element. This spectrometer was associated with a large sensitive area (f ¼ 40 mm) micro-channel plates assembly. This apparatus provides simultaneously high spectral (l=dlB1800) and spatial (100–200mm) resolutions. Its large tunability allowed, without any adjustment of the spectrometer set-up, to record spectra in the 1.38–17.5 ( A wavelength range. We used the X-ray emission of femtosecond laser-produced plasmas from different materials ((CF2)n, CaF2, Cu, Al) to test the spectrometer. Thanks to the high sensitivity (high collection efficiency) of the system, high quality space-resolved X-ray spectra of Fluorine and Aluminum plasmas were obtained on a single laser shot. r 2001 Elsevier Science B.V. All rights reserved.

A capillary discharge soft X-ray laser operating at 46.9 rim on the transition 3p–3s (J=0−1) of the Ne-like Ar has been realized by exciting the active medium with a long half-cycle duration current pulse of 140 ns. The current is produced by discharging a 10 nF water dielectric capacitor, initially charged to voltages lower than 200 kV by a six stage Marx generator, through a 15-cm long capillary channels. The laser amplification has been obtained by properly adjusting all the other experimental parameters. Utilizing a 3-mm in diameter AI2O3 capillary channel initially filled with 0.3 torr of Ar pressure, a laser beam, which has a 4-mrad divergence and a time duration of 1.3 ns, is characterized by a gain of 0.6 ± 0.1 cm−1. The stability of the plasma compression followed by the laser emission is verified.

We report on the spectra of x-rays emitted from dense plasma generated via irradiation of thin stainless steel foils by ultra-relativistic femtosecond laser pulses (intensities ~3 × 10^21 W/cm^2). Kinetic modelling was used to estimate electron plasma density and temperature, demonstrating Te ~2.1 keV for Ne ~5 × 10^22 cm^−3 in the hottest emission region. Thus, it is experimentally demonstrated for the first time that the laser pulse of over 10^21 W/cm^2 intensity is absorbed neither in the solid density plasma nor in a pre-plasma of a common critical density, but in the matter of so called relativistic critical density.

By means of spatially resolved high-resolution X-ray spectroscopy, we have investigated the generation of fast ions at various laser installations with different flux densities and laser wavelengths. It is demonstrated that the fast ion generation in laser-produced plasma can be achieved for a very low level of the averaged laser intensity on the target. The time-of-flight mass spectrometry ion diagnostics and X-ray spectrographs give very close results for the energy distribution of the thermal ion component. For higher energies, however, we found significant differences: the spatially resolved high-resolution spectrographs expose the presence of suprathermal ions, while the time-of-flight method does not. Suprathermal ion energies Eion plotted as a function of the qλ2 parameter show a large scatter far above the experimental errors. The cause of these large scatters is attributed to a strong nonuniformity of the laser intensity distribution in the focal spot. The analysis by means of hydrodynamics and spectral simulations show that the X-ray emission spectrum is a complex convolution from different parts of the plasma with strongly different electron density and temperature. It is shown that the highly resolved Li-like satellite spectrum near Heαcontains significant distortions even for very low hot electron fractions. Non-Maxwellian spectroscopy allows determination of both the hot electron fraction and the bulk electron temperature.

Primary and aggregate color centers in lithium fluoride (LiF) crystals and polycrystalline LiF films were produced by an innovative irradiation technique using extreme ultraviolet radiation and soft X-rays generated by a laser-plasma source. This irradiation facility allowed the efficient formation of active color centers on luminescent patterns with submicron spatial resolution on large areas and short exposure times. The method looks promising for the realization of low-dimensionality photonic devices. The optical characterization of the colored structures was performed by means of absorption and photoluminescence measurements on LiF samples colored under different irradiation conditions.

The X-ray spectra of multiply charged ions were recorded from planar agar (C12H18O9)n based targets with an average density of 2 mg cm-3 irradiated by high-power laser pulses (λ=1.054 μm, τ=2.5 ns, I ≈ 5 ×1013 W cm-2). The spectra were recorded with a high spectral and spatial resolution employing spherically bent (focusing) crystals of mica and quartz. An analysis of the experimental data obtained by the irradiation of Al2O3-doped agar samples allowed us to determine the main parameters of the plasma produced inside the targets. The ion temperature of plasma in low-density porous targets was estimated for the first time to be 1.5 — 2 times higher than the electron temperature.

Un laser a excimeres de grand volume, HERCULES-L, a ete developpe dans le cadre d'un programme europeen pour des applications industrielles concernant le traitement de surface du silicium et la generation de plasmas par laser. Les performances de ce laser sont particulierement adaptees pour le traitement de grandes surfaces et pour la creation de photons EUV (hv 100 eV) par plasma assiste par laser.

Atomic argon clusters were created using various types of nozzles and gas jet backing pressures. High temperature plasmas were created by irradiating the clusters with high intensity 35 fs laser pulses. The data obtained from these experiments were compared with each other as well as an experiment using a longer pulse ( 60 fs ) higher flux density laser. Detailed spectroscopic analysis of high resolution X-ray data near the Heα,Heβ, and Lyα lines of Ar was consistent with a two-temperature collisional-radiative model incorporating the effects of highly energetic electrons. Each variation has an effect on the rate of cluster expansion; therefore, results of the analysis provide useful insight into the behavior of such plasmas over short time scales. It was demonstrated for the first time, that by using sufficiently large clusters, hydrogen-like ions of Ar with an ionization potential of approximately 4120 eV could be obtained with a 35 fs laser pulse with a relatively low flux density of 1×10 17 W/cm 2 .

The generation of fast particles (both ions and electrons) in a femtosecond laser-produced plasma has been studied experimentally and the possibility of applying particle-in-cell (PIC) codes to the description of the experimental results has been investigated. The energy distribution function of fast ions has been measured directly by means of X-ray spectroscopy. It is shown that this diagnostic can also be used as an indirect method to measure fast electrons inside the plasma. The hot electron distribution in the 0:1–2 MeV energy range was measured directly using a standard electron magnetic spectrometer. The comparison of the experimental results with the numerical simulations show: (1) the electromagnetic PIC-FC code can be successfully applied for simulating plasmas created by the interaction of femtosecond-laser pulses with solid targets and (2) the existence of a transient population of hot electrons with a non-Maxwellian distribution typical of interaction experiments with short-pulse lasers. ? 2001 Elsevier Science Ltd. All rights reserved.

A novel, compact, large field, and spectrally tunable imaging x-ray microscope is presented. It is based on the use of an isotropic point x-ray source and a spherically curved crystal. The x-ray beam intensity is modulated by the object attenuation, then monochromatized and enlarged using a spherical crystal and, finally, imaged using a detector downstream from the crystal. We demonstrate by ray tracing simulations that this system allows microscopy studies with high spatial resolution, high magnification ratios, and large field of view. Microscopes using this model can be easily built using different x-ray sources, like conventional x-ray tube generators, x rays emitted by laser-generated plasmas or x-pinch plasmas, and also synchrotron radiation when used in combination with other condenser optics. Preliminary experiments are presented to demonstrate the feasibility of the proposed setup. High resolution (∼4 μm) monochromatic (δλ/λ∼10−5–10−3) images over a large field of view (few mm2) were recorded in ...

A study on the interaction of a 10 TW, 60 fs, Ti–Sapphire laser with a high-density long-scale pulsed nitrogen gas jet is reported. Experimental data on the laser propagation are analyzed with the help of a ray-tracing model. The plasma dynamics is investigated by means of time-resolved shadowgraphy and time-integrated high-resolution x-ray spectroscopy. Shadowgrams show that the plasma does not expand during the first 55 ps, while x-ray spectra exhibit an unusual continuum-like structure attributed to hollow atoms produced by charge exchange process between bare nuclei expelled from the plasma and molecules of the surrounding gas. The interpretation of the results is supported by particle-in-cell simulations. The question of x-ray lasing is also examined using a hydrodynamic code to simulate the long lasting regime of recombination.

The high efficiency method of transient collisional excitation has been successfully demonstrated for Ne-like and Ni-like ion x-ray laser schemes with small 5-10 J laser facilities. Our recent studies using the tabletop COMET (Compact Multipulse Terawatt) laser system at the Lawrence Livermore National Laboratory (LLNL) have produced several x-ray lasers operating in the saturation regime. Output energy of 10-15 {micro}J corresponding to a gL product of 18 has been achieved on the Ni-like Pd 4d {yields} 4p transition at 147 {angstrom} with a total energy of 5-7 J in a 600 ps pulse followed by a 1.2 ps pulse. Analysis of the laser beam angular profile indicates that refraction plays an important role in the amplification and propagation process in the plasma column. We report further improvement in the extraction efficiency by varying a number of laser driver parameters. In particular, the duration of the second short pulse producing the inversion has an observed effect on the x-ray laser output.

It was established experimentally that the number and energy of fast ions in laser plasma increased with increasing angle of focusing laser radiation onto a flat target. Numerical calculations showed that the increase in angle of focusing brought the mean angle of incidence of laser radiation closer to the optimal angle corresponding to the maximal efficiency of the resonance absorption mechanism and, as a result, increased the fraction of absorbed laser energy in the energy of fast electrons and increased the number of fast electrons. In turn, the increase in the energy and number of fast electrons resulted in an increase in the number of fast electrons involved in the formation of a self-consistent electric field at the target edge and led to the growth of the field strength, which, eventually, was the reason for the increase in the number and energy of fast ions.

A portable (200×100×100 mm3), high-luminosity, spherically bent crystal spectrometer was designed for measuring in a wide spectral range of 1.2–19.6 A very low emissivity x-ray spectra of different clusters heated by 35 fs laser radiation. This spectrometer is associated with a custom design x-ray charge coupled device that features a large sensitive area (24.6×24.6 mm2) and a small pixel size (24×24 μm2). This apparatus provides simultaneous high spectral (λ/δλ∼1000–5000) and spatial (40–80 μm) resolution. A large (30×10 mm2) open aperture mica crystal with R=100 mm is used as the dispersive and focusing element. The large tuneability of the spectrometer makes it possible to record high-resolution spectra of H-like ions of oxygen (CO2 clusters) in a spectral range of 15–17 A, Ne-like like ions of Kr in a spectral range of 5–5.7 A, and He-like spectra of Ar in a spectral range of 3.0–3.4 and 3.7–4.4 A without any adjustment of the spectrometer setup. Thanks to the high luminosity (high collection efficien...

The shadow monochromatic backlighting (SMB) scheme, a modification of the well-known soft X-ray monochromatic backlighting scheme, is proposed. It is based on a spherical crystal as the dispersive element and extends the traditional scheme by allowing one to work with a wide range of Bragg angles and thus in a wide spectral range. The advantages of the new scheme are demonstrated experimentally and supported numerically by ray-tracing simulations. In the experiments, the X-ray backlighter source is a laser-produced plasma, created by the interaction of an ultrashort pulse, Ti:Sapphire laser (120 fs, 3–5 mJ, 1016 W/cm2 on target) or a short wavelength XeCl laser (10 ns, 1–2 J, 1013 W/cm2 on target) with various solid targets (Dy, Ni + Cr, BaF2). In both experiments, the X-ray sources are well localized spatially (∼20 μm) and are spectrally tunable in a relatively wide wavelength range (λ = 8–15 Å). High quality monochromatic (δλ/λ ∼ 10−5–10−3) images with high spatial resolution (up to ∼4 μm) over a large field of view (a few square millimeters) were obtained. Utilization of spherically bent crystals to obtain high-resolution, large field, monochromatic images in a wide range of Bragg angles (35° < Θ < 90°) is demonstrated for the first time.

The first observation of x-ray emission spectra of multiply charged ions in the plasma produced by a 35-fs laser pulse with an intensity up to 1017 W cm-2 in CO2 and Kr gas jet targets is reported. The emission in the wavelength ranges of the 1snp—1s2(n=3–6) transitions of O VII ions and the Lyα line of O VIII ions, as well as of the (2s1/22p63p3/2)1—2s22p6 1S0 and (2s1/22p63p1/2)1—2s22p6 1S0 lines of Ne-like KrXXVII ions testifies that the highly ionised plasma is formed by collision processes in clusters. Modelling the shape of the spectral lines of oxygen ions by including the principal mechanisms of broadening and absorption in optically dense plasmas reveals that the main contribution to the time-integrated intensity is made by the plasma with the parameters Ne=(2–20)×1020 cm-3 and Te=100 — 115 eV.

Complex spectral structures located between the resonance lines of H- and He-like MgXII and MgXI ions were recorded in experiments on plasma heating by the radiation of a low-power short-wavelength excimer XeCl laser (12-ns pulses with an energy of 2 J). The above spectral structures were shown to arise from transitions in the so-called hollow multicharged ions, i.e., in ions with an empty 1s-shell, which were previously observed in laser produced plasmas only with ultrahigh-power femto- and picosecond laser facilities having extremely high-contrast laser pulses.

The evolution of the ion composition of a laser plasma during its expansion over a large distance is studied. The plasma is produced by a TIR CO2 laser with a pulse energy up to 100 J and duration of ∼20 ns. X-ray diagnostics with the use of a spectrograph and X-ray PIN diodes was applied to study the plasma near the target surface. At large distances from the target surface, time-of-flight neutral-particle diagnostics with the use of an electrostatic analyzer and ion collector was applied. Calculations performed with the GIDRA-1 code agree well with experimental data.

The interaction of a 60-fs laser pulse with argon clusters was experimentally studied. It is shown that cluster heating by an intense femtosecond pulse preceded by a picosecond prepulse can produce plasma whose ionization state is determined by the prepulse properties, while the mean energy of hot electrons is determined by the main pulse intensity. A simple model of cluster plasma evolution is suggested, allowing an adequate description of its X-ray emission.

New types of space resolved X-ray spectra produced in light matter experiments with high intensity lasers have been investigated experimentally and theoretically. This type of spectra is characterised by the disappearance of distinct resonance line emission and the appearance of very broad emission structures due to the dielectronic satellite transitions associated to the resonance lines. Atomic data calculations have shown, that rather exotic states with K-shell vacancies are involved. For quantitative spectra interpretation we developed a model for dielectronic satellite accumulation (DSA-model) in cold dense optically thick plasmas which are tested by rigorous comparison with space resolved spectra from ns-lasers. In experiments with laser intensities up to 10 19 W/cm 2 focused into nitrogen gas targets, hollow ion configurations are observed by means of soft X-ray spectroscopy. It is shown that transitions in hollow ions can be used for plasma diagnostic. The determination of the electron temperature in the long lasting recombining regime is demonstrated. In Light-matter interaction experiments with extremely high contrast (up to 10 10 ) short pulse (400 fs) lasers electron densities of n e ≈3×10 23 cm −3 at temperatures between kT e =200–300 eV have been determined by means of spectral simulations developed previously for ns-laser produced plasmas. Expansion velocities are determined analysing asymmetric optically thick line emission. Further, the results are checked by observing the spectral windows involving the region about the He α -line and the region from the He β -line to the He-like continuum. Finally, plasmas of solid density are characteristic in experiments with heavy ion beams heating massive targets. We report the first spectroscopic investigations in plasmas of this type with results on solid neon heated by Ar-ions. A spectroscopic method for the determination of the electron temperature in extreme optically thick plasmas is developed.

The unique combination of an intense heavy ion beam and a high-energy Nd:glass laser system at Gesellschaft f Schwerionenforschung (GSI-Darmstadt) facilitates pioneering beam-plasma interaction experiments and thus allows to address basic physics issues associated with heavy ion-driven inertial fusion. The deposition power of the intense heavy ion beam from the synchrotron has recently been increased to 1 kJ/g. The hydrodynamic response of solid targets was measured. A comparison with detailed numerical simulations attributes the target response to a pressure pulse of 3 GPa at a maximum temperature of 2500 K. Beam plasma interaction experiments to measure the stopping power of laser plasmas for heavy ion beams have been performed and show an increased energy loss for Ni ions in a 60 eV dense carbon plasma. Subsequently performed time-resolved charge-state measurements indicate that the increased stopping power can partially be attributed to a high charge state of the beam ions traversing the plasma. Improved plasma diagnostic by high-resolution spectroscopy revealed the unexpected existence of He-like resonance and intercombination lines (Heaa 1s2p 3 P1‐1s 2 and Yaa 1s2p 3 P1‐1s 2 ) of fluorine even for a modest laser intensity of 5 · 10 11 W/cm 2 . ” 2000 Elsevier Science B.V. All rights reserved.

We have observed evidence of the emission of energetic He-and H-like ions of fluorine more than 1 MeV produced via the optical field ionization (OFI) from a solid target irradiated by an intense I=(2-4)x10(18) W/cm(2) (60 fs, lambda=800 nm), obliquely incident p-polarized pulse laser. The measured blue wing of He(alpha), He(beta), and Ly(alpha) lines of fluorine shows a feature of the Doppler-shifted spectrum due to the self-similar ion expansion dominated by superthermal electrons with the temperature T(h) approximately 100 keV. Using a collisional particle-in-cell simulation, which incorporates the nonlocal-thermodynamic-equilibrium ionization including OFI, we have obtained the plasma temperature, line shape, and maximal energy of accelerated ions, which agree well with those determined from the experimental spectra. The red wing of ion spectra gives the temperature of bulk plasma electrons.

A new approach for investigation of the generation of fast ions and hot electrons inside the same plasma volume in laser-produced plasmas is proposed. It is based on the spectroscopic observation of line radiation from singly and doubly excited levels with simultaneous high spectral and spatial resolution. The experimental results demonstrate the observation of fast ions from highly charged target material inside the plasma volume and suggest that the generally accepted scaling relations are seriously invalid under certain conditions. Even at rather modest intensities ions with energies of several MeV are observed.

The x-ray spectra of a plasma generated by heating CO2 and Ar clusters with high-intensity femtosecond laser pulses with q las≃1018 W/cm2 are investigated. Spatially resolved x-ray spectra of a cluster plasma are obtained for the first time. Photoionization absorption is observed to influence the spectral line profiles. The recorded features of the x-ray emission spectra definitely indicate the existence of a large relative number of excited ions (≃10−2–10−3) with energies of 0.1–1 MeV in such a plasma. Possible mechanisms underlying the acceleration of ions to high energies are discussed. It is shown that the experimental results can be attributed to the influence of ponderomotive forces in standing waves generated by the reflection of laser radiation from the clusters.

In laser-produced plasmas, the interaction of the intense laser light with plasma electrons can produce high-energy superthermal electrons with energies in the keV range. These hot electrons can influence the level populations which determine spectral line structure. In the present paper, the effect of hot electrons on the X-ray satellite spectrum of laser-produced plasmas is studied. Calculated spectra are compared with experimental observations. Magnesium targets irradiated by three different types of laser pulses are considered. These include, a high-intensity 600 fs Nd-glass laser, a 1 ns Nd-glass laser, and a 2 ns CO 2 laser. The Nd-glass laser experiments were conducted recently at the Los Alamos Trident Facility and the CO 2 data were recorded by MISDC. High-resolution spectra were measured near the He-like resonance line of magnesium. The calculations employ an electron energy distribution which includes a thermal and a hot electron component, as part of a detailed collisional-radiative model. Plasma parameters including electron temperature, density, and hot electron fraction are estimated by choosing best fits to the experimental measurements. The calculations show that hot electrons can cause several anomalous effects. The Li-like jkl, abcd , and qr satellites can show intensities which are generally attributed to electron densities in excess of 10 23 cm -3 . In addition, the relative amplitude of the intercombination line can be unusually large even at high electron densities due to enhanced collisional excitation of the 1 s2p 3 P state by hot electrons.

Ray-tracing simulations, validated by experimental results, demonstrate that high intensity collimated x-ray beams can be produced from an isotropic x-ray source. A spherically bent mica crystal was used to collimate and monochromatize x rays emitted by a femtosecond laser-produced plasma. The result is a short pulse x-ray beam with a high degree of collimation (less than 1 mrad divergence), good spectral resolution (10−2

The combination of a table-top laser produced plasma X-ray source and a spherically bent crystal for the soft X-ray region is used in traditional X-ray microscopy schemes. The X-ray source is well localized both spatially ( ~ 20µm) and temporally ( ~ 1ps) and is spectrally tunable in a relatively wide range (6–14A). High quality monochromatic (δλ/λ ~ 10-5–10-4) images with high spatial resolution (up to ~ 4µm) and in a large field of view (few mm) are presented. For many applications, this low-cost compact system can offer a simple alternative to the larger installations, which are usually used. The spherically bent crystals can be used in a wide range of reflection angles, thus allowing wavelength selection.

For the first time registration of high-resolution soft x-ray emission and atomic data calculations of hollow-atom dielectronic satellite spectra of highly charged nitrogen have been performed. Double-electron charge-exchange processes from excited states are proposed for the formation of autoionizing levels in high-intensity laser-produced plasmas, when field-ionized ions penetrate into the residual gas. Good agreement is found between theory and experiment. Plasma spectroscopy with hollow ions is proposed and a temperature diagnostic for laser-produced plasmas in the long-lasting recombining regime is developed.

Ultrashort-pulse, laser-produced plasmas have become very interesting laboratory sources to study spectroscopically due to their very high densities and temperatures, and the high laser-induced electromagnetic fields present. Typically, these plasmas are of very small volume and very low emissivity. Thus, studying these near point source plasmas requires advanced experimental techniques. We present a new spectrometer design called the focusing spectrometer with spatial resolution (FSSR-2D) based on a spherically bent crystal which provides simultaneous high spectral (λ/Δλ≈104) and spatial resolution (≈10 μm) as well as high luminosity (high collection efficiency). We described in detail the FSSR-2D case in which a small, near point source plasma is investigated. An estimate for the spectral and spatial resolution for the spectrometer is outlined based on geometric considerations. Using the FSSR-2D instrument, experimental data measured from both a 100 fs and a nanosecond pulse laser-produced plasma are presented.

On the basis of experimental and theoretical investigations it is demonstrated for the first time that in cold dense optically thick laser-produced plasmas, created near the target surface, the capture into the He-like ground state is negligible for line formation and that observed high-intensity -Rydberg satellite intensities are correlated with highly populated He-like excited states . X-ray emission spectra with simultaneous high spectral and spatial resolution provide a direct verification of the proposed excitation mechanism. Atomic data calculations for all configurations with n = 3 - 6 have been carried out and were employed in spectral modelling. Taking into account the proposed excitation channels, excellent overall agreement is found. Successful cross-checks with the spectral interval near the -line are demonstrated. The spectral modelling is proposed for sensitive density (electron density, excited state population) and temperature diagnostics near the target surface.

A hydrodynamic model of the interaction of a short, intense laser pulse with moderate-density gases is constructed. The model systematically takes into account both tunneling-ionization processes and the relativistic motion of the electrons that are produced by the ionization of the gas in the relativistically strong field of the pulse. X-ray spectroscopy data agree well with the proposed theory.

The x-ray spectra of a plasma produced by heating CO2 clusters with intense femtosecond laser pulses with λ=0.8 μm and λ=0.4 μm are investigated. Spatially resolved x-ray spectra of the cluster plasma are obtained. The observed characteristic features of the x-ray emission spectra show unequivocally that such a plasma contains quite a large relative number of ions (≃10−2–10−3) with energies of 0.1–1 MeV. The contour of the OVIII Lyα line is found to have characteristic features that are especially conspicuous when the clusters are heated with second-harmonic pulses. These features cannot be explained by any mechanisms known to the authors.

A highly stripped barium plasma is produced by 120-fs laser pulses irradiating a ${\mathrm{BaF}}_{2}$ target. The spectrum emitted by the plasma in the 9.10\char21{}9.36-\AA{} wavelength range is recorded using a high-resolution spherically bent mica crystal. On the basis of the HULLAC atomic code, a level-by-level collisional-radiative model including autoionization and dielectronic capture processes is developed to calculate the wavelengths and intensities of the spectral lines emitted by each of the Cu-, Zn-, and Ga-like barium ions. $3d\ensuremath{-}nf$ $(n=6,7)$ spectral lines with different spectator electrons, previously observed only as unresolved transition arrays, are resolved. The theoretical results agree reasonably well with experiment. Best agreement is obtained for electron density and temperature of $5\ifmmode\times\else\texttimes\fi{}{10}^{21}{\mathrm{cm}}^{\mathrm{\ensuremath{-}}3}$ and 120 eV, respectively. The intensity ratios of the resolved Cu-like barium lines are shown to be useful tools for electron density and temperature diagnosis. This diagnostic method was not possible with low-resolution spectroscopy. It is found that at relatively low temperature and high density as in the present experiment, the relative intensities of lines within each ionization state are independent of the ion density ratio of adjacent ionization states.

Spherically curved crystal spectrometers are demonstrated for use on an Electron Beam Ion Trap (EBIT) for the first time. Such spectrometers are characterized by high light collection efficiency and relative insensitivity to source position, simultaneously, giving them an advantage that no X-ray spectrometer previously used on an EBIT has had. One of the spectrometer crystals tested is composed of mica, giving it the additional advantage that it can be used with reasonable efficiency up to very high order, allowing spectra to span a broad wavelength range from 0.5 Angstroms to 20 Angstroms. Spectra from Ne-like barium and He-like argon are presented.

A new type of quasicontinuous emission spectrum from a femtosecond laser plasma near the Lyα line of H-like ions is obtained and interpreted. It is shown that these spectra are emitted by multiply charged hollow ions, which are present in the plasma on account of its ultrahigh density, which, in turn, is due to the use of high-contrast laser pulses for producing the plasma. A new spectroscopic approach based on analysis of the composition of spectral complexes of hollow ions is discussed.

Time- and space-integrated emission spectra measurements have been performed in plasma produced by 308 nm wavelength XeCl laser radiation (IL = (4–10)·1012 W/cm2, τ = 10 ns) and by 248 nm wavelength KrF laser pulse train radiation (IL = 5·1015 W/cm2, τ = 7 ps, 16 pulses in train) on CF2 plane target. Theoretical modelling of Lyman series and He-like ion resonance series of fluorine and its fit of experimental data show considerable differences in the absorption of laser radiation in the two plasmas.

Essential parameters for the application of crystals to quantitative X-ray spectroscopy are the upper wavelength limit and the quantitative reflection properties (intrinsic resolving power, luminosity) of the crystal. Due to the large lattice constant, muscovite, a mica group mineral, can be used in the wavelength range up to about 2nm. Muscovite crystals can be bent to small radii of curvature due to their favourable cleavage and elastic properties. Characteristic reflection properties at reflections 002 – 00 24 were investigated theoretically and experimentally. The integrated reflectivity was calculated for various reflections of perfect flat as well as spherically bent muscovite crystals with curvature radii R = 100 and R = 186mm. It was measured for flat crystals in the reflections 00 10 – 00 26 using CuKα- and MoKα-radiation from X-ray tubes and compared with calculations for both perfect and mosaic crystals. Available high-quality muscovite crystals have a mosaic structure with a mosaic spread of about 1 arcmin. This mosaic spread limits the spectral resolving power for high reflection orders.

We investigated the ion characteristics in picosecond laser plasma at laser radiation intensity of up to 2 × 10 18 W/cm 2 . Our experimental observations of X-ray spectral line profiles confirmed the presence of a great quantity of high-energy ions (∼ 1 MeV) in laser plasma. Besides, by the L yα Doppler profile's red shift we revealed the high-energy ion motion directed inward the target. For this phenomenon we suggest our theoretical model. The high energy "tail" in the energy spectrum of ions in laser plasmas can be explained by the pinch effect. The effective way for production of beams of charged particles in laser plasmas is the electric drift of these particles in electromagnetic fields generated in the laser-produced plasmas.

High intensity laser-plasma interaction has attracted considerable interest for a number of years. The laser-plasma interaction is accompanied by generation of various charged particle beams, such as high-energy proton and ions with high charge to mass ratio (Q/M; same as multi-charged ions). Results of simultaneous novel measurements of electron-induced photonuclear neutrons (photoneutron), which are a diagnostic of the laser-plasma interaction, are proposed to use for optimization of the laser-plasma ion generation. The proposed method is demonstrated by the laser irradiation with the intensity of 1 × 10(21) W/cm(2) on the metal foil target. The photoneutrons are measured by using NE213 liquid scintillation detectors. Heavy-ion signal is registered with the CR-39 track detector simultaneously. The measured signals of the electron-induced photoneutrons are well reproduced by using the Particle and Heavy Ion Transport code System. The results obtained provide useful approach for analyzing the various laser based ion beams.

Experimental demonstration of multi-charged heavy ion acceleration from the interaction between the ultra-intense short pulse laser system and the metal target is presented. Al ions are accelerated up to 12 MeV/u (324 MeV total energy). To our knowledge, this is far the highest energy ever reported for the case of acceleration of the heavy ions produced by the10 J laser energy of 200 TW class Ti:sapphire laser system. Adding to that, thanks to the extraordinary high intensity laser field of ∼10(21) W cm(-2), the accelerated ions are almost fully stripped, having high charge to mass ratio (Q/M).

Observations were made of expansion, in a transverse quasisteady magnetic field (B ≈ 10 T), of a Teflon plasma generated by Nd laser radiation (λ = 1.06 μm, E ≈ 6 J, and τ ≈ 1ns). Time-integrated two-dimensional images of the plasma radiance were obtained in the spectrum of continuous and line x-ray radiation and spectroholiograms were recorded of 21P1—11S0 and 23P1—11S0 lines of the He-like F VIII ion. The plasma radiation was found to be anisotropic relative to the expansion axis and the dependence of the intensity on the distance from the target changed as a result of the influence of the transverse magnetic field on the plasma dynamics.

Soft x-ray spectra originating from dense plasmas, generated by a laser irradiating a solid target with ns- and fs- laser pulses, have been obtained with simultaneous high spectral ( λ δλ ≈ 10000 ) and spatial resolution (δx ≈ 10 μm). Interesting structure of the He-like resonance line together with strong emission of the Li-like n = 2 satellites have been observed very close to the target surface. We show here that the resonance line structure is strongly influenced by higher order satellites of the type 1s2n1'-1s21n' which overlap for n > 2. For plasmas created with short pulse duration lasers there are high density and low temperature regions near the target that give rise to three body recombination into Rydberg satellite levels leading to substantial intensity at the position of the resonance transition. Atomic data necessary for spectra simulations have been calculated with inclusion of configuration interaction and relativistic effects and these results are cross-checked with other calculational methods. Time-dependent simulations of the spectra including the effects of optical thickness, energetic electrons and numerous high order Rydberg satellites (up to n = 7) are found to be in good agreement with experimental data.

The properties of a monochromatic x-ray backlighting system based on a spherically bent crystal were investigated. Simulations of spatial resolution for spherically bent crystals with different radius of curvature and for several wavelengths of incidence radiation were done using the ray-tracing method. Test experiments were carried out to demonstrate the high spatial resolution using the incoherent soft x-ray radiation produced by laser- and x-pinch plasmas. Both experimental and theoretical results show that a spatial resolution of at least 4 μm can be obtained in a field of view ranging from a few mm to cm. The narrow spectral band of the diffracted beam (Δλ/λ ~ 3 × 10−4), the high efficiency of the presented scheme and the possibility of significantly reducing the self radiation of the studied object make it one of the most promising backlighting systems. This scheme permits the essential reduction of requirements of the source of radiation and could be a less costly alternative to using x-ray lasers for such purposes.