Journal of X-Ray Science and Technology - Volume 4, issue 1
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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: B K-reflection spectra for grazing incidence angles (θ0 = 4°, 8°), calculated absorption spectra, and angle-dependent scattering distributions at different grazing incidence angles and different wavelengths from hexagonal BN have been described. The reflection and scattering from a surface cut parallel and perpendicular to the c-axis of the crystal have been studied. The strong anisotropy of ultrasoft x-ray reflection and scattering has been discovered.
Abstract: We describe a XUV spectrometer for the study of dense hot microplasmas at wavelengths between ≈50 and ≈300 Å. It uses a commercially fabricated grazing incidence flat-field reflection grating with 1200 grooves per millimeter. The spectral resolution was optimized by imaging the source on a narrow slit with the help of a curved grazing incidence mirror. The instrument was tested with a laser-produced plasma as a source. The limit of the resolving power due to imaging aberrations of the flat-field grating ranges from 1500 at 50 Å to 3600 at 200 Å and has been achieved with a 5-μm slit.…We also measured and calculated the grating efficiencies for the first to fifth diffraction order as a function of wavelength.
Abstract: Resolution in x-ray backscatter imaging has often been hampered by low fluxes. But, for a given set of resolution requirements and geometric constraints, it is possible to define a maximization problem in the geometric parameters for which the solution is the maximum flux possible in those circumstances. In this way, resolution in noncritical directions can be traded for improved resolution in a desired direction. Making this the thickness, or surface normal direction, makes practicable the depth profiling of layered structures. Such techniques were applied to the problem of imaging the layered structure of corroding aircraft sheet metal joints using Compton…backscatter.
Abstract: Destructive interference of waves scattered from both interfaces of a thin film deposited onto a rough substrate is theoretically shown to lead to considerable suppression (up to some orders) of x-ray scattering intensity. The conditions that are necessary for the suppression of scattering are discussed.
Abstract: A new technique for the generation of picosecond x-ray pulses is presented. Picosecond laser pulses are used to generate ultrashort electron pulses in a conventional x-ray diode in which the cathode is replaced by a photocathode. In the experiments presented, 9-ps UV pulses are employed to produce characteristic x-ray pulses with duration in range of 20-90 ps at a repetition rate of 300 Hz. This technique is inherently capable of subpicosecond x-ray pulses and synchronization of the x-ray pulses with the laser pulses or other ultrafast devices with picosecond accuracy.
Abstract: Two experiments were performed to determine whether impurity content and transport information could be extracted from low-resolution XUV spectra recorded from a simple spectroscopic diagnostic that utilized a flat multilayer mirror as the dispersive element. The first experiment, at the DIII-D tokamak, compared MLM spectra to higher-resolution spectra and found that the low-resolution MLM spectra were sufficient to distinguish changes in impurity emission patterns. The results demonstrated the feasibility of building simple MLM-based diagnostics for impurity monitors in the harsh environment of future tokamaks. The second experiment, at the Texas Experimental tokamak, compared MLM spectra to those produced by an…impurity transport code coupled to a collisional-radiative model. The comparison showed that it is possible to distinguish changes in impurity transport from low-resolution MLM spectra.
Abstract: The basic concepts and properties of some phase-space mathematical functions, in particular of the Wigner distribution function, are reviewed. Then, the propagation and diffraction of x rays are considered from the point of view of the Wigner function, resulting in a simple method consisting in coordinate shifts in phase space, which can be easily implemented in a personal computer. The applications of this tool to x-ray technology are also discussed.