X-ray microscopy of laser-produced plasmas with the use of bent crystals

Abstract

X-ray spectroscopical and microscopical methods are used for the determination of the spectral and spatial distribution of X-ray intensity of laser-produced plasmas. The use of Bragg reflections of two-dimensionally bent crystals enables the X-ray microscopical imaging in narrow spectral ranges (AX/X = 10~4 to 10~2) with wavelengths 0.1 nm < X < 2.6 nm. It is possible to adapt, in the X-ray microscope, the distances, magnification, position, and width of the spectral window to the special conditions of the laser facility. Manufacturing and testing of the two-dimensionally bent crystals requires a great deal of effort. It was demonstrated that a spatial resolution of about 5 /xm was achieved, and that the experimentally determined reflectivity was found to be in close agreement with the dynamical theory of X-ray interferences. Due to high luminosity of the X-ray microscope, in experiments with laser-produced plasmas it was necessary to attenuate the radiation with aperture-limiting diaphragms or filters down to 0.01-1% of the original intensity in the case of a magnification of about one. Emission of the resonance line W 1-2, the intercombination line of helium-like ions, and Lyman alpha line were imaged simultaneously with a three-channel microscope. Such images form the foundation for establishing the 7V e (r), T z (r) maps.

X-ray and ion emission studies from subnanosecond laser-irradiated SiO2 aerogel foam targets

“…The production of small, compact, easily accessible and short pulse length X-ray sources from laser plasma interactions has significantly facilitated research in advanced science such as radiobiology, X-ray microscopy, micro-lithography, astrophysical and fusion applications, measurement of the opacity of materials, X-ray driven shock studies for Equation-of-State (EOS) measurements of materials under extreme conditions and time resolved x-ray diffraction of materials (Loupias et al, 2009;Rossall et al, 2010;Daido et al, 2002;Keiter et al, 2008;Lewis et al, 1984;Chaker et al,1988;Förstera et al, 1989;O'Neill et al, 1989;Lindl et al, 1995; . Rischel et al, 1997;Borisenko et al, 2006).…”

Multispectral x-ray imaging with a pinhole array and a flat Bragg mirror

“…Spherically-bent [3] or toroidally-bent [4] Bragg crystals can be used as imaging elements, and an array of such crystals -tuned for different energies through slight variations in Bragg angles -can provide a number of quasi-monochromatic images at discrete energies across a desired range [5]. A simpler approach [6] uses an array of pinholes as the imaging element, and uses a flat Bragg mirror to provide energy dispersion.…”

Focusing of millijoule picosecond Kα radiation from 100 TW laser-solid interaction

“…The basic physical picture of the generation process states that during the interaction of an intense laser pulse with a solid target, a hot electron population is generated through different absorption mechanisms such as, for instance, resonant absorption, vacuum heating, or parametric instabilities. The collection and monochromatization have been achieved using two-dimensionally bent crystals [15][16][17] but with an overall efficiency limited to 1.1ϫ 10 −4 . 8 This x-ray emission is mainly temporally limited by the electron acceleration duration, i.e., about the laser-target interaction time and the mean excursion time of the electrons inside the target in the range of picosecond duration.…”