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The possibility of using the relative intensities of the 1snp 1P1–1s 2 1S0 transitions with n = 3–6 in He-like multicharged ions to diagnose plasma in a nonstationary ionization state is considered. The calculations performed for F VIII ions show that, at electron temperatures of T e = 10–100 eV, the intensity ratios are sensitive to the plasma electron density in the range of N e = 1016–1020 cm–3. The universal calculated dependences can be used to diagnose various kinds of recombining or ionizing plasmas containing such ions.

A superbright X-ray source with a radiation temperature of ~1.2 keV making it possible to create a solid-state plasma whose kinetics is determined by the radiative processes has been implemented under the impact of a 170-TW pulse of the PEARL femtosecond laser facility on an aluminum target with submicron thickness. The diagnostics of the created plasma is performed by X-ray spectral methods using spectral transitions in hollow multicharged ions.

Basic nuclear-astrophysics problems that can be studied under laboratory conditions at a laserradiation intensity of 1018 W/cm2 or more are specified. These are the lithium problem, the problem of determining neutron sources for s-processes of heavy-element formation, the formation of bypassed stable p-nuclei, and nuclear reactions involving isotopes used by astronomers for diagnostics purposes. The results of experiments at the Neodym laser facility are presented, and proposals for further studies in these realms are formulated.

A combination of a petawatt laser and nuclear physics techniques can crucially facilitate the measurement of exotic nuclei properties. With numerical simulations and laser-driven experiments we show prospects for the Laser-driven Exotic Nuclei extraction–acceleration method proposed in [M. Nishiuchi et al., Phys, Plasmas 22, 033107 (2015)]: a femtosecond petawatt laser, irradiating a target bombarded by an external ion beam, extracts from the target and accelerates to few GeV highly charged short-lived heavy exotic nuclei created in the target via nuclear reactions.

The Spectr-W3 database was developed in 2001–2013 and is available online (http://spectrw3. snz.ru). The database contains information on various spectroscopic constants of atoms and ions such as the wavelengths and probabilities of radiative transitions, energy levels of atoms and ions, ionization potentials, autoionization rates, and the parameters of analytical approximation of cross sections and rates of collisional transitions in atoms and ions. Spectr-W3 presently contains around 450 thousand records and is the world’s largest factual database on spectral properties of multicharged ions. A new stage of development of Spectr-W3, which involves adding a new section titled “Emission Spectrograms” to the database, commenced in 2014. In contrast to the already existing sections that contain tabulated data, this new section provides graphical data (with necessary explanatory notes) on the spectrograms of emission of atoms and ions excited in various plasma sources. The structure of sections of the Spectr-W3 database is characterized, and examples of queries and the corresponding search results are given.

The investigation of a recombining laser plasma is topical primarily because it can be used to simulate the interaction between plasma jets in astrophysical objects. It has been shown that the relative intensities of transitions of a resonance series of He-like multicharged ions can be used for the diagnostics of the recombining plasma. It has been found that the intensities of the indicated transitions for ions with the nuclear charge number Z n ~ 10 are sensitive to the plasma density in the range N e ~ 1016–1020 cm–3 at temperatures of 10–100 eV. The calculations performed for the F VIII ion have determined the parameters of plasma jets created at the ELFIE nanosecond laser facility (Ecole Polytechnique, France) in order to simulate astrophysical phenomena. The resulting universal calculation dependences can be used to diagnose different recombining plasmas containing helium-like fluorine ions.

It is proposed to use a high rate of collisional ionization in a superdense laser plasma to generate incoherent femtosecond X-ray pulses. The calculations indicate that the use of picosecond laser pulses with a contrast of about 1010 will allow the generation of an X-ray pulse with a duration of about 10 fs. The adequacy of the proposed model of the excitation of linear X-ray radiation from the plasma has been tested in the experiments with a picosecond laser of a moderately high contrast.

The results of work on choosing and substantiating promising lines of research in the realms of laboratory astrophysics with the aid of powerful lasers are presented. These lines of research are determined by the possibility of simulating, under laboratory conditions, problematic processes of presentday astrophysics, such as (i) the generation and evolution of electromagnetic fields in cosmic space and the role of magnetic fields there at various spatial scales; (ii) the mechanisms of formation and evolution of cosmic gamma-ray bursts and relativistic jets; (iii) plasma instabilities in cosmic space and astrophysical objects, plasma jets, and shock waves; (iv) supernova explosions and mechanisms of the explosion of supernovae featuring a collapsing core; (v) nuclear processes in astrophysical objects; (vi) cosmic rays and mechanisms of their production and acceleration to high energies; and (vii) astrophysical sources of x-ray radiation. It is shown that the use of existing powerful lasers characterized by an intensity in the range of 1018–1022 W/cm2 and a pulse duration of 0.1 to 1 ps and high-energy lasers characterized by an energy in excess of 1 kJ and a pulse duration of 1 to 10 ns makes it possible to perform investigations in laboratory astrophysics along all of the chosen promising lines. The results obtained by experimentally investigating laser plasma with the aid of the laser facility created at Central Research Institute of Machine Building (TsNIIMash) and characterized by a power level of 10 TW demonstrate the potential of such facilities for performing a number of experiments in the realms of laboratory astrophysics.

The effects of self-absorption of X-ray spectral lines have been experimentally observed in the plasma of cluster targets. It has been shown that, since a cluster target is condensed in the femtosecond time scale and gaseous in the picosecond time scale, self-absorption effects can observed for X-ray spectral lines that are predominantly emitted during the action of a laser pre-pulse. The self-absorption effects are manifested as spectral lines with asymmetric profiles where the long-wavelength wing is suppressed compared to the short-wavelength wing. The observation of asymmetric contours is important for the diagnostics of the laser-cluster interaction because it enables the conclusion of whether the laser pre-pulse completely destroys the cluster and makes it possible to quantitatively estimate the size of the central region of the cluster, which has a solid-state density to the moment of the arrival of the main laser pulse.

The interaction of radiation of a picosecond X-ray laser (wavelength λ = 13.9 nm) with targets made of a thick gold film has been studied theoretically and experimentally. It has been shown experimentally that the action of individual X-ray laser pulses with a fluence of F ≈ 21 mJ/cm2 initiates the nanostructuring of the gold surface. Explicitly taking into account the electron subsystem, we have proposed an atomistic model of ablation that makes it possible to adequately describe the experimental results. The atomistic simulation involves the ion-ion potential depending on the electron temperature T e . The use of such a potential makes it possible to take into account an increase in the pressure in the system with increasing T e and to reveal two laser ablation mechanisms.

We study the charcteristics of X-ray radiation of a laser plasma generated in the interaction of a femtosecond pulse with solid targets in an air medium and conside the possibility of using it for radiography. We show that the mechanism for generating X-ray radiation in the interaction of short, powerful laser pulses with solid targets in a gas atmosphere is related to the generation of fast electrons in the gas breakdown region. We prove experimentally that under such conditions, even under relatively low laser radiation densities

X-ray diagnostics of the interaction of femtosecond laser pulses with intensities of 1016–1018 W/cm2 with CO2 clusters and frozen nanosize water particles is carried out. The stage of cluster expansion and the formation of a plasma channel, which governs the parameters of the formed X-ray radiation source and accelerated ion flows, is studied. The measurements are based on recording spatially resolved X-ray spectra of H- and He-like oxygen ions. Utilization of Rydberg transitions for spectra diagnostics makes it possible to determine plasma parameters on a time scale of t ∼ 10 ps after the beginning of a femtosecond pulse. The role of the rear edge of the laser pulse in sustaining the plasma temperature at a level of ∼100 eV in the stage of a nonadiabatic cluster expansion is shown. The analysis of the profiles and relative intensities of spectral lines allows one to determine the temperature and density of plasma electrons and distinguish the populations of “thermal” ions and ions that are accelerated up to energies of a few tens of kiloelectronvolts. It is shown that the use of solid clusters made of frozen nanoscale water droplets as targets leads to a substantial increase in the number of fast He-like ions. In this case, however, the efficiency of acceleration of H-like ions does not increase, because the time of their ionization in plasma exceeds the time of cluster expansion.

The characteristics of X rays of a laser plasma generated in the interaction of a femtosecond pulse with solid targets in an air atmosphere have been investigated. It has been shown that the mechanism for the generation of X rays in the interaction of short intense laser pulses with solid targets in a gas atmosphere is attributed to the generation of fast electrons in the region of the filamentation of a laser pulse. It has been proven experimentally that under such conditions, the solid target irradiated by laser radiation of even a low density of about 1015 W/cm2 very efficiently emits ∼10-keV photons. It has been shown theoretically that the maximum energy of accelerated electrons can reach ɛmax ∼ 100–200 keV under these conditions. This means that the proposed method can provide characteristic radiation with the energy of photons much higher than 10 keV.

It has been shown that a femtosecond plasma of cluster targets is an almost isotropic source of fast ions and, hence, can be used to obtain ionographic images with a wide field of view. The spatial resolution of the resulting ionographic images is no worse than 600 nm, which corresponds to a uniquely high value of about 105 of the ratio of the field of view to the resolution. The use of 100–300-keV ion fluxes ensures the sensitivity of the method to the sample thickness of no worse than 100 nm even for samples consisting of light chemical elements (C, H). The proposed method can be used to obtain images of low-contrast biological objects, thin films, membranes, and other nanostructured objects.

We have measured the energy of the directed motion of multiply charged ions produced when solid targets are exposed to low-contrast (10−3–10−2) femtosecond laser pulses with intensities 1015–1016 W cm−2. The measurements are based on the recording of spatially resolved X-ray spectra for H-and He-like oxygen ions in the target plane. Analysis of the Heβ and Lyα line profiles has revealed fractions of accelerated ions in plasma with energies from several to several tens of kiloelectronvolts. We show that using a layer of frozen nanometer-size water droplets as the targets leads to an effective absorption of laser pulses and a twofold rise in the energy (to 0.1 MeV) of He-like oxygen ions compared to the use of solid targets.

At high intensities of interaction of femtosecond laser pulses with various targets, numerous high-energy particles emitted from plasma in all directions lead to the appearance of parasitic peaks in the X-ray spectra of femtosecond laser plasma (FLP) during detection of these peaks with a detector based on a charge-coupled device (CCD). The algorithm proposed in this study allows identification of parasitic peaks in a series of experimental spectra, which are recorded for each pixel of the CCD detector independently of other pixels, and removal of these peaks. The algorithm is able to detect peaks in the presence of both variations in the intensities of spectral lines and very intense noise. The efficiency of the algorithm has been confirmed via testing with the use of a series of model spectra and spectra of Fe and Al ions recorded in experiments devoted to studies of the interaction of ultrahigh-intensity and ultrashort laser pulses with solid targets.

As femtosecond laser pulses increase in intensity and decrease in duration, interaction between the focused laser radiation and a substance is followed by a sharp increase in the intensity of fast-electron, ion, and electromagnetic noise generation. In turn, the noise signals of X-ray detectors grow in amplitude and the signal-to-noise ratio in recording X-ray spectra of multiply charged ions approaches unity. A significant excess of the noise level over the useful signal is observed in plasmas generated by laser pulses with a power density of >= 10(17) W/cm(2). The most powerful effect of the above factors is exerted on X-ray spectra recorded by such electromagnetic equipment as CCD-based detectors, photoelectron amplifiers, etc. A new '' mean-median '' algorithm is described, with which it is possible to considerably increase the signal-to-noise ratio of CCD detectors used to measure X-ray spectra of femtosecond laser-produced plasma.

X-ray spectra from Teflon targets irradiated by laser pulses with a duration of 60 fs to 1 ps have been investigated experimentally. It is shown that, when the contrast of the laser pulse is sufficiently low, the effect of self-focusing of the main laser pulse in the plasma produced by the prepulse can significantly enhance the generation efficiency of fast particles. In this case, ions with energies as high as similar to 1 MeV are observed at relatively low laser intensities, q(las) approximate to (4-6) x 10(16) W/cm(2).

Experimental data on neutron production in a plasma generated on a Be target by a picosecond laser of intensity 2 x 10{sup 18} W/cm{sup 2} are presented. In contrast to previous measurements, a Ta converter is not used in this study to generate {gamma} rays. The neutron yield is equal to 2 x 10{sup 3} over a solid angle of 4{pi} steradians per laser pulse. A simultaneous measurement of the maximum energy of hard x rays gave E{sub {gamma}}{sub max} {approx} 6 MeV, the number of these photons being 5 x 10{sup 8} over an angle of 4{pi} steradians per laser pulse. The energy distributions of fast electrons and photons are estimated theoretically.

Experimental data are reported on the generation of fast ions in a picosecond laser plasma at a laser-radiation intensity of 2 × 1018 W/cm2. The results are obtained by measuring the Doppler spectra of hydrogen-like fluorine ions. An important feature of the energy distribution of fast ions is a slow decrease up to an energy of 1.4 MeV. In addition, the directional motion of fast ions deep into a target is found due to the redshift of the Doppler profile of the Ly α line. The parameters of the energy distribution of the ions are theoretically estimated.

X-ray spectroscopic data are reported on the state of a silicon aerogel medium (SiO2) irradiated by a Ni ion flux with an energy of 4.7 MeV/nucleon. Radiation from the electron transitions to the K shell in multicharged Si ions is detected with spatial resolution along the direction of the beam propagation in the medium. Calculations performed for the ionization state and population of the levels excited in the silicon atoms of the target provide the estimate T e = 70–120 eV for the medium electron temperature in the ion tack region. Two-dimensional hydrodynamic calculations provide the estimate T e = 60–116 eV for the same conditions and densities of 0.5–2.5 g/cm3 of the excited target medium.

The interaction of femtosecond laser pulses with SiO2 aerogel targets has been analyzed by x-ray spectroscopic methods. The use of an aerogel target with transparent grains makes it possible to considerably reduce the requirements on laser-pulse contrasts for which heating occurs without the formation of a preplasma. A nanoplasma with a density sevenfold higher than the solid-state density has been detected.

We present the results of our measurements of the spectra for multicharged ions in a plasma produced by moderately intense (about 1017Wcm−2) picosecond laser pulses. They suggest the existence of intense plasma oscillations with a frequency appreciably lower than the frequency of the laser radiation. The observed spectrum for the plasma satellites of the Lyman Lyα doublet of the hydrogenic F IX ion in a dense plasma was modeled theoretically. The resulting doublet profile was shown to have a complex structure that depends non-trivially both on the plasma density and on the frequency and amplitude of the plasma oscillations. The positions of the satellites and their separations allowed them to be associated with intense electrostatic oscillations with an amplitude of (4–6)×108Vcm−1 and a frequency near (0.7–1)×1015s−1. Assuming the oscillation frequency to be determined by the strength of the magnetic field B generated in the plasma, we obtained an estimate of B that is in reasonable agreement with other measurements and estimates of this quantity. Our theoretical analysis allowed explanation of the emission spectra observed when flat fluoroplastic targets were heated by intense picosecond laser pulses.

Interaction between high-power ultrashort laser pulse and giant clusters (microdroplets) consisting of 109 to 1010 atoms is considered. The microdroplet size is comparable to the laser wavelength. A model of the evolution of a microdroplet plasma induced by a high-power laser pulse is developed, and the processes taking place after interaction with the pulse are analyzed. It is shown theoretically that the plasma is superheated: its temperature is approximately equal to the ionization potential of an ion having a typical charge. The microdroplet plasma parameters are independent of the pulse shape and duration. The theoretical conclusions are supported by experimental studies of x-ray spectra conducted at JAERI, where a 100-terawatt Ti-sapphire laser system was used to irradiate krypton and xenon microdroplets by laser pulses with pulse widths of 30 to 500 fs and intensities of 6×1016 to 2×1019W/cm2.

Neutron production as a result of the reaction 2H(d, n)3He in a picosecond laser plasma is reported. A considerable neutron yield of 5×104 per pulse is obtained for the first time in a picosecond laser plasma on the surface of a solid deuterated target at laser radiation intensity of 3×1017 W/cm2.

The problem of increasing the mean size of clusters in gas-jet targets is tackled. Based on a mathematical model of clustering, the dependence of the cluster mean size on the nozzle length and rate of expansion is derived. The nozzle shape providing micrometer-size clusters is found. The parameters of gas-jet targets produced with this nozzle are studied in detail.

The X-ray lines of ions in a solid target interacting with picosecond laser pulses of moderate intensity (2×1017 W/cm2) were measured on the “Neodim” laser facility. X-ray Ly α emission spectra of hydrogen-like fluorine ions were observed. Satellite lines were also observed, evidencing the presence of intense plasma oscillations. The positions and separation between the satellites allow their assignment to the intense electrostatic oscillations with an amplitude larger than 108 V/cm and a frequency of about 7× 1014 s−1 that is noticeably lower than the laser frequency ωlas∼1.8×1015 s−1. It is suggested that these oscillations may be due to strong plasma turbulence caused by the development of plasma oscillations of the Bernstein-mode type under the action of a strong magnetic field generated in plasma. The experimental results are compared with the calculated spectra of multicharged ions.

Variation of the velocity of Ca6+ ions with initial energies of 5.9 and 11.4 MeV/nucleon has been experimentally studied in the course of ion stopping in a solid aerogel target. The method is based on measuring the Doppler shift in the K-shell spectrum of decelerated Ca19+ and Ca18+ ions. High spatial resolution (30–50 mm) in the direction of the ion beam propagation achieved simultaneously with high spectral resolution (λ/Δλ=1000–3000) in the X-ray wavelength interval of 2–4 A allowed the ion beam dynamics in the solid target to be directly measured. By measuring variations in the relative intensity of spectral lines, it is possible to monitor the redistribution of the ions over charged states during their motion in the target.

We have measured the X-ray emission spectra of a plasma generated by laser radiation with an intensity above 1019W/cm2 and a pulse duration of 30 fs acting upon an argon jet target with a large abundance of micron-sized clusters. The time variation of the X-ray yield from ions of various multiplicities, calculated within the framework of a nonstationary kinetic model, shows a good qualitative agreement with the experimental time-integrated spectrum.

X-ray emission spectra of the plasma created at the surface of magnesium, aluminum, copper, and zinc targets heated by 1-ps laser pulses with a peak power density of up to 1016 W/cm2 were measured. The effect of a picosecond prepulse on the spectra was studied for various power densities and intensity contrasts of the main laser pulse. It is established that the emission spectra of laser plasmas are weakly affected by a change from 105 to 107 in the main pulse contrast relative to the first prepulse. Variations in the parameters of emission from aluminum and magnesium plasmas were calculated using relative intensities and widths of the resonance lines of H-and He-like ions and their two-electron satellite peaks.

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.

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.

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.

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.

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.

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 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.

Laser satellites are detected in the emission spectra of magnesium and aluminum plasmas produced by femtosecond laser pulses. This is made possible by the realization of picosecond time resolution in a high-luminosity x-ray spectrograph with a spherically curved mica crystal. The temporal characteristics of these newly recorded spectral lines show unequivocally that they are formed as a result of nonlinear processes.

The first experimental studies of an electron beam generated in an X pinch on the XP machine (Cornell University, USA) and the BIN machine (P. N. Lebedev Physical Institute, Russian Academy of Sciences) are reported. It is shown that it is possible in an X pinch to isolate the effect of a plasma-generated electron beam on the multiply charged ion radiation. The intensities of the satellite lines corresponding to Li-, Be-, B-, and C-like ions are calculated for the Al spectrum on the basis of a collisional-radiative model with a non-Maxwellian electron distribution in the plasma. The effect of an electron beam on the multiply charged light ion radiation in an X-pinch plasma is demonstrated. Comparing our calculations with the experimental spectra, we conclude that the present model can be used to estimate the electron beam intensity.

It is shown that in a dense, not very hot, multiply charged plasma the satellite structures of resonance lines can become more intense than the resonance lines themselves. Experimental and theoretical investigations show that the conditions under which the satellite structures dominate in the emission spectrum of the plasma are quite easily realized experimentally and, furthermore, apparently they will be the most typical case in investigations of compressed plasma regions in inertial-confinement fusion experiments and in the study of plasma produced by high-contrast pico-and femtosecond laser pulses.

Differences between X-ray argon clusters excited at the laser-cluster and laser-droplet interactions have been analyzed. X-ray spectral methods have been proposed to determine the parameters of the appearing plasma at the early stages of its evolution. It has been shown that the spectra of hollow ions are the most informative in the first moments of the heating of a cluster, whereas the diagnostics of the late stages can be performed using the conventional lines of multicharged ions.