X-ray emission from planar targets irradiated by 1.054-μm laser pulses was observed with temporal, spatial, and spectral resolution. The main purpose of these measurements was the investigation of energy transfer in multilayer targets and X-ray conversion efficiency. A mass ablation rate was determined from temporal analysis of multicharged ion line emission and a key role of corona X-ray emission in accelerated material preheating was established.

The X-ray emission from laser-produced plasmas at an X-ray wavelength of approximately 10.4 nm was measured for Al and Gd target materials. The laser power density on the target surface was varied between 1.5 × 1010 and 3 × 1012 W/cm2 to obtain different electron temperatures. The output from the plasma was measured using an X-ray reflecting Pd-C multilayer coating as a wavelength-selective element and a diamond photoconductive detector. The emission at 10.4 nm is strongest at the low end of the power density range investigated. A strong increase is found for Al targets due to a contribution of line radiation, which is not present in the Gd plasmas. The measured conversion efficiency for Al plasmas was (4.5 ± 1)% in a 3% bandwidth at an X-ray wavelength of 10.4 nm.

In this article, we present the formation of an elongated plasma column by combining a laser plasma with an external magnetic field. The laser plasma is produced by irradiating solid targets with a focused Nd-glass laser. The targets were placed on the axis of the two, single-turn magnetic coils, which provided a magnetic field up to 500 kg in the target region. The expanding laser plasma is confined by the magnetic field and an elongated and uniform plasma column is formed on the axis of the coils. The plasma column emits strong, soft X-ray radiation. The pinhole photographs show that the plasma column is at least 5 mm long. To study the interaction of the expanding laser plasma with a magnetic field, the laser probing diagnostic was used.

The effect of laser intensity distribution along the line focus on the uniformity of the line-shaped plasmas produced is investigated with time-integrated and time-resolved soft X-ray and optical diagnostics. Evident plasma condition nonuniformities along the line focus resulting from nonuniform laser intensity distributions have been observed with a conventional simple line-focusing technique. With a new line-focusing technique producing a uniform laser illumination, a uniform, line-shaped plasma can be obtained. It is also found that nonuniformities under uniform laser illumination occur mostly during laser heating. The line-shaped uniform laser plasma can be used as a large, uniform X-ray source besides its importance in X-ray laser demonstration and amplification. As an application of such line-shaped plasmas as X-ray sources, the no-overcoat 5F X-ray film is calibrated for the first time by a new method in the soft X-ray range from 10–80 A.

It is shown that large gainlengths of amplified spontaneous emission (ASE) together with collisional effects in plasmas are liable to generate modifications in population inversions and then in observed gain values. In the case of the Ne-like Se24+ ion, one can expect a significant reduction of the J = 0–1 transition gain value at the wavelength of 18.24 nm.

A study of the effects of photoionization of a laser-produced plasma has been carried out by modeling the fluorescence of resonance lines due to cascades. The photoionization source is the X-ray M-band emission of a laser-produced high-Z plasma and it perturbs a ground state He-like aluminum plasma. Simulations have been performed to study the conditions necessary to maximize the fluorescence and guide future experiments. A collisional-radiative model is used to determine the optimal temperature and density of the pumped plasma, while hydrodynamic models are used to produce realistic plasma gradients and explore the optimum time delay of the photopumping.

Experimental investigations of laser-produced plasma expansion in a strong (−20 T) magnetic field have been carried out. The image and spectra of the plasma flame in the soft X-ray spectral region have been obtained. It has been shown that the strong magnetic field limits the transverse plasma expansion and strongly effects the ion-level populations.

The possibility of the occurrence of a population inversion between n = 3, 2 levels in H-like Al, as well as between levels of the n = 4, 3 manifold in He-like Al, has been inferred from time integrated K-line intensity ratios. Opacity-corrected inversion factors (1 − Ni/Nj) of about 0.6 for both He- and H-like Al have been obtained in counterstreaming Al-Au plasmas from which gain values of about 0.5 cm−1 have been estimated.

Atomic processes in X-ray laser interaction plasmas are investigated by using a collisional-radiative model. Population inversions on free-bound transitions can be produced by photoionization above a threshold of incident X-ray laser intensity and lead to stimulated free-bound emission (SFBE). Free-bound lasers pumped by intense X-ray lasers are proposed and their feasibility is investigated simply considering X-ray laser interaction plasmas.

Soft X-ray imaging detection is usually made by using 101–01, 101–07, or SA1 Kodak films. Recent progress in thinned CCD fabrication allows us now to replace films by thinned CCDs to detect UV soft X-ray light with an enhanced sensitivity. We developed a thinned CCD system, and to demonstrate its applicability to replace photographic films we tested it behind a broad spectral range soft X-ray transmission grating spectrometer and a soft X-ray Mo/Si multilayer mirror telescope. Soft X-ray spectra and soft X-ray pictures of laser-created plasma are presented using these instruments implemented with a thinned CCD readout.

Vertical dispersion variant of the double-crystal spectrograph is analyzed and its basic quantitative characteristics (luminosity, resolving power) are computed using ray tracing code. It is shown that geometric apparatus smearing is minimized due to high dispersion and spectral resolution may considerably exceed the single-crystal diffraction limit. Performing high-resolution spectral work, the efficiency of the double-crystal apparatus exceeds that of the flat single-crystal spectrograph. The usefulness of this method in laser plasma spectroscopy is demonstrated analyzing the detection of phosphorus He-like resonance line and its satellites.

The imaging spectrograph with spherical crystal and transmission grating have been used to obtain the high spectrally and spatially resolved images of plasma X-ray microsources (fast z-pinch) as well as of laser-produced plasma flares up to 5 mm in extent. The spectral resolution λ/Δλ = 2·104 have been achieved using a quartz spherical mirror with the curvature radius 500 mm. Using a transmission grating spectrometer, the spectral density of power about 105 W/A in the “water window” has been measured in experiments with a fast z-pinch large pulse storage facility.

Two methods of target technology for investigation of X-ray laser–plasma emission are presented. The first deals with steel and gold microcapillary targets. They are about 200 μm in inner diameter and about 500 μm in length. The second method deals with metal plus plastic targets of reduced and controlled density in the range of 1.6–8.1 g/cm3 for Cu + polyethylene (PE) and 1.6–7.6 g/cm3 for Fe + PE.

A modular cw CO2 transverse flow, self-sustained discharge-excited laser at an average output power of 1.2 kW was designed and built at the IFFM of the Polish Academy of Sciences for industrial applications. Performance characteristics of the laser measured for a stable resonator folded into different types of multipass configurations are reported and compared.

A construction and exploitation of a comparatively large I photodissociation laser system (Perun) is reported. This system was constructed in cooperation between the Institute of Physics of Czechoslovak Academy of Science in Prague and the Lebedev Institute of Physics of Soviet Academy of Science in Moscow. The laser produces subnanosecond pulses of maximum 50 J and 0·5 ns in duration. Although the pumping time by Xe flashlamps is long enough for an acoustic disturbance released in the active medium to introduce an optical inhomogeneity across the whole cross section of the laser tube, the radiation can be focused in a focal spot of a power density exceeding 1014 W/cm2, enough for meaningful laser target experiments both for a laser plasma production or a modification of solid surfaces. The repetition time of the shots is about 10 min.