Characterization of laser-produced plasma x-ray sources for use in x-ray radiography

Abstract

We report the absolute conversion efficiency ξx from the incident laser light energy to x-ray photons for laser-produced plasmas. Potential x-ray backlighting (radiography) line sources having photon energies from 1.4 to 8.6 keV are studied as a function of laser wavelength, pulsewidth, and intensity. The laser intensity and pulsewidth range from 1014 to 1016 W/cm2, 100 ps to 2 ns and include incident wavelengths of 1.06, 0.53, and 0.35 μm. We found that K-shell x-ray line emission ξx : (1) decreases with increasing x-ray energy, (2) decreases with increasing laser intensity, (3) decreases rapidly with pulselength, and (4) moderately increases with decreasing laser wavelength. On the contrary, for Au M band emission, at a fixed laser intensity and pulsewidth, ξx significantly increases (∼25×) upon decreasing the laser wavelength from 1.06 to 0.35 μm.

<title>Scaling of x-ray K-shell sources from laser-solid interactions</title>

“…This is often seen most clearly in the x-ray spectra. 3 In this paper we investigate the scaling of x-ray yield and conversion efficiency over a large range of energies using the OMEGA laser facility at the University of Rochester. 12 In particular we concentrate on the scaling of xray yield and conversion efficiency with laser irradiance and target material.…”

“…Some of this experimental work has previously been done. [2][3][4][5][6][7][8][9][10][11] The problem encountered by the experimentalist is that the number of data points is limited and those that do exist often disagree. In some cases discrepancies can be explained by the differences between lasers (in particular the far field distribution).…”

Charge Carrier Density and signal induced in a CVD diamond detector from NIF DT neutrons, x-rays, and electrons

“…40 The x-ray flux generated by the laser photons hitting a nickel or zinc target is large enough, with over 10 11 x-rays/cm 2 produced at 10 cm from the target (7.5 keV to 8.6 keV x-rays lines). 41 Double pulses can be obtained as well. However, the fluctuations in the laser intensity may be a limitation to obtain a uniform x-ray flux at the detector.…”

X-ray induced pinhole closure in point-projection x-ray radiography

“…variations in x-ray conversion efficiencies reported previously 16,17 and inherent complexities of modeling non-ideal low temperature dense plasmas 18 , it is hence important to measure the onset of closure in current experiments and use the results to validate hydrodynamic computations that could serve as a predictive tool for future experiments.…”