Journal of X-Ray Science and Technology - Volume 5, issue 3
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Journal of X-Ray Science and Technology is an international journal designed for the diverse community (biomedical, industrial and academic) of users and developers of novel x-ray imaging techniques. The purpose of the journal is to provide clear and full coverage of new developments and applications in the field.
Areas such as x-ray microlithography, x-ray astronomy and medical x-ray imaging as well as new technologies arising from fields traditionally considered unrelated to x rays (semiconductor processing, accelerator technology, ionizing and non-ionizing medical diagnostic and therapeutic modalities, etc.) present opportunities for research that can meet new challenges as they arise.
Abstract: In a dense and hot plasma the refractive index in the X-UV range takes into account not only the effect of free electrons, but also the effect of electrons bound by atoms. The refractive index is calculated by the Kramer-Kronig relations using the total opacity of the medium including bound-bound, free-bound, and free-free atomic transitions. A simple method of calculation of the emission and absorption coefficients is presented. These parameters are of great interest when one wants to study radiative transfer in a dense and hot material. The computer program used allows one to obtain either in LTE or in…NLTE the values of these coefficients for every material and for a wide range of mass density and temperature, using a screened hydrogenic model. Applications are presented first to generate opacity tables and second to generate the index of refraction of aluminum for a wide range of mass density and temperature.
Abstract: We report the characterization of a soft x-ray plasma source generated by a long-pulse XeCl excimer laser system. The output energy is 4 J at a wavelength of 308 nm in a 100-ns pulse. The intensity of radiation on target is estimated to be 4 × 1012 W cm−2 . X-ray emission spectra of the plasma have been recorded using a double focusing spatial resolution spectrometer with a spherical mica crystal. From these measurements, the plasma temperature and electron density have been estimated. Various applications of such a plasma source have been investigated. First images of whole intact living…cells from our system, imaged using the technique of soft x-ray contact microscopy, utilizing x rays in the “water window” region (280–530 eV), are shown. The suitability of the source for other applications, for example, x-ray lithography and radiation damage studies, to living cells are discussed. Possible improvements to the x-ray source for the various applications are proposed.
Abstract: We have performed experiments using magnetocumulative generators (MCGs) to power three different types of high-energy-density plasma discharges suitable for intense x-ray generation. They include the H-pressed discharge, the capillary z-pinch, and the θ-pinch. The MCGs were operated with, and without, plasma opening switches. The characteristic currents were approximately 10 MA and characteristic time scales approximately 1 μs. In this paper we describe the characteristics of these experiments.
Abstract: The results of experiments with a plasma x-ray source in the PIRIT-2000 facility are presented in this paper. The facility is designed with module capacitive energy storage energizing vacuum inductive storage. The formation of a rapidly growing current pulse as well as its commutation on a load was carried out by a plasma opening switch. A vacuum diode as well as various types of plasma loads can be used for the generation of a high-power x-ray flux. The storage energy of a 54-module capacitive storage is up to 2 MJ, its inductance is 15 nH, and its output voltage is…500 kV. The peak current in the plasma load constituted 4 MA with a 150-ns rise time. The maximum integral energy output of x radiation measured by an open thermocouple calorimeter was as high as 100 kJ, while the primary storage energy was 1 MJ. The plasma load usage at a current of 4 MA ensured a 100-kJ generation in x-ray radiation and the density of the radiation flux at a distance of 1 m from the source was as much as 0.8 J/cm2 , while near the source it was 10 J/cm2 .
Abstract: This paper gives the results of studies on a plasma x-ray source, which enables one to obtain a 2.5-krad radiation dose per pulse over an area of 100 cm2 in the quantum energy range from 20 to 500 keV. Pulse duration is 100 ns. Spectral radiation distributions from a diode under various operation conditions of a plasma are obtained. A Marx generator served as an initial energy source of 120 kJ with a discharge time of T/4 = 10−6 s. A short electromagnetic pulse (10−7 s) was shaped using plasma erosion opening switches.
Abstract: Annealing effects in the short-period multilayers Cr3 C2 /C, TiC/C, Cr3 C2 /(B + C), and CrB2 /C were studied in a wide temperature range ~200–1200°C by x-ray scattering and cross-sectional electron microscopy. It was shown that the thermodynamic equilibrium of the layer materials at their interfaces and stabilization of layer structure by impurities and heat treatment are effective approaches to short-period multilayers with enhanced thermal stability of their structure and optical properties.
Abstract: The operation of x-ray lasers has been successfully demonstrated in laser-produced plasmas. Pulsed-power-driven plasmas of imploding liners offer potentially higher overall efficiencies and less expensive drivers as compared with laser-produced plasmas. Stabilization of a liner implosion is the main problem to be solved to achieve x-ray lasing in liners. Stable liner implosions can be obtained using some methods of liner stabilization. A helical driving magnetic field, a double shell liner structure, and initial axial magnetic field were used to stabilize liner implosions on the SNOP-3 generator (Imax ≃ 1.1 MA, τ ≃ 100 ns). Using a capillary discharge in…Fe2 O3 to form the inner shell, a stable pinch of iron-bearing plasma with a diameter 150–200 μm and an ion density of (2–4) × 1020 cm−3 was observed. Comparison with theoretical calculations shows that it is possible to create conditions conducive to lasing in neon-like iron using double shell liner implosions On the SNOP-3 generator.
Abstract: We have measured the far-field angular distribution of high-order harmonic beams generated in low-density gas at the focus of an intense laser beam. The experimental setup created conditions where the harmonics could be thought of as emerging from a two-dimensional plane at the focus rather than from a three-dimensional interaction region. Under these conditions, harmonic light scattered into broad angles indicates that intrinsic phases develop at the atomic level between the laser field and the emitted individual harmonics and that this phenomenon has a strong dependence on the laser intensity. Because the laser intensity varies radially in the focus, intensity-dependent…phases cause the emerging harmonic beams to have distorted wave fronts which result in broad scattering. These conclusions are in agreement with theoretical calculations and have interesting implications.
Abstract: Bragg x-ray optics based on crystals with transmission and reflection properties bent on cylindrical or spherical surfaces are discussed. Applications of such optics for obtaining one- and two-dimensional monochromatic images of different plasma sources in the wide spectral range 1–20 Å are described. Samples of spectra obtained with spectral resolution of up to λ/Δλ ~ 10,000 and spatial resolution of up to 18 μm are presented.