X-ray emission from plasmas created by smoothed KrF laser irradiation

Abstract

The x-ray emission from plasmas created by the Naval Research Laboratory Nike KrF laser [Phys. Plasmas 3, 2098 (1996) ] was characterized using imaging and spectroscopic instruments. The laser wavelength was 1/4 μm, and the beams were smoothed by induced spatial incoherence (ISI). The targets were thin foils of CH, aluminum, titanium, and cobalt and were irradiated by laser energies in the range 100–1500 J. A multilayer mirror microscope operating at an energy of 95 eV recorded images of the plasma with a spatial resolution of 2 μm. The variation of the 95 eV emission across the 800 μm focal spot was 1.3% rms. Using a curved crystal imager operating in the 1–2 keV x-ray region, the density, temperature, and opacity of aluminum plasmas were determined with a spatial resolution of 10 μm perpendicular to the target surface. The spectral line ratios indicated that the aluminum plasmas were relatively dense, cool, and optically thick near the target surface. The absolute radiation flux was determined at 95 eV and in x-ray bandpasses covering the 1–8 keV region. The electron temperature inferred from the slope of the x-ray flux versus energy data in the 5–8 keV region was 900 eV for an incident laser energy of 200 J and an intensity of ≊1013 W/cm2.

Basic hydrodynamics of Richtmyer–Meshkov-type growth and oscillations in the inertial confinement fusion-relevant conditions

“…The optical scheme of monochromatic X-ray backlighting (Rode et al 1990;Pikuz, S. A. et al 1995aPikuz, S. A. et al ,b, 1997Pikuz, T. A. et al 1995;Aglitskiy et al 1996;Brown et al 1997a,b;Pawley et al 1997;Sanchez del Rio et al 1997) is presented in figure 1. Imaging of just top and bottom points of the main target is shown.…”

Measurements of laser-imprinted perturbations and Rayleigh–Taylor growth with the Nike KrF laser

“…The back-lighter x-ray source was created by using eight Nike beams (total energyϭ350 J) that were slightly defocused to give an oval focal spot 600 m wide by 800 m high on an aluminum target. 19 The x rays propagate through the main target, through a 10 m beryllium shield in front of the pinholes, and then through a 10 m thick silicon K-edge filter behind the pinholes. This filter transmits the 1.6 and 1.7 keV He-like Al and H-like Al line groups.…”

The role of hollow atoms in the spectra of an ultrashort-pulse-laser-driven Ar cluster target

“…Emission from hollow atoms have also been used as a diagnostic for studies of warm dense matter. Experimentally, the formation of hollow atoms has been achieved through neutralization of highly charged ions within solids (Briand et al, 1990(Briand et al, , 1996Gauthier et al, 1995;Aglitsky et al, 1996;Suto & Kagawa, 1998;Moribayshi et al, 2001;Rosmej et al, 2000), through collisions in cluster targets (McPherson et al, 1994a(McPherson et al, , 1999b, and even in gaseous targets . More recently, hollow atom spectra have been explored from heavy atom targets (Diamant et al, 2000a(Diamant et al, , 2000b(Diamant et al, , 2001Shigeoka et al, 2004) using synchrotron radiation.…”