Efficient Multi-keV X-Ray Sources from Ti-Doped Aerogel Targets

Fournier, K. B.; Constantin, Carmen; Poco, J.F.; Mc, Miller; Ca, Back; Lj, Suter; Satcher, Joe H.; Davis, J.; Grün, J.

doi:10.1103/physrevlett.92.165005

Cited by 89 publications

(40 citation statements)

References 21 publications

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“…Laserheated targets typically contain mid-Z elements such as Ti, Fe, V, Ge, or Kr, their K-shell line emission providing 4 to 15 keV x rays. For instance, metal foils 4 , gasfilled targets 5,6 , metal-doped aerogels [7][8][9] , pre-exploded foils 10 , metal oxide nano-fibers 11 , and aerogels attached to foils 12 , can achieve 1 to 10% laser-to-x-ray conversion efficiencies (CE) in a limited energy range. Metal-doped foams can reach high CEs when their density is low enough (< 10 mg/cm 3 ) so that the laser gets absorbed deeper in the target thus volumetrically heating the plasma.…”

Section: Introductionmentioning

confidence: 99%

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Bright x-ray sources from laser irradiation of foams with high concentration of Ti

et al. 2014

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Low-density foams irradiated by a 20 kilojoule laser at the Omega laser facility (NY, USA) are shown to convert more than 5% of the laser energy into 4.6 to 6.0 keV x rays. This record efficiency with foam targets is due to novel fabrication techniques based on atomic-layer-deposition of Ti atoms on an aerogel scaffold. A Ti concentration of 33 atomic % was obtained in a foam with a total density of 5 mg/cm 3 . The dynamics of the ionization front through these foams were investigated at the 1 kilojoule laser of the Gekko XII facility (Japan). Hydrodynamic simulations can reproduce the average electron temperature but fail to predict accurately the heat front velocity in the foam. This discrepancy is shown to be unrelated to the possible water adsorbed in the foam but could be attributed to effects of the foam micro-structure.

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Section: Introductionmentioning

confidence: 99%

“…Various types of such foams can, in principle, be achieved by tailoring the material composition, density, and pore size. Previous work 7,8 has shown that foams containing various dopants (Ti, Fe, Ge, etc.) could be volumetrically heated when the density is in the range of 5 to 10 mg/cm 3 .…”

Section: Introductionmentioning

confidence: 99%

Bright x-ray sources from laser irradiation of foams with high concentration of Ti

et al. 2014

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“…The target design for the current experiments builds on experience at the Nova 29 and Omega 30 laser facilities using modeling and simulation tools that have been validated against experiments [12][13][14][15][16][17][18][19][20][21][22][23][24] . The desired x-ray source characteristics for the present experiments were: a) significant multi-keV x-ray output with energies >3 keV, b) x-ray pulse width of order 5 ns, and c) x-ray rise-time of order 1 ns or longer.…”

Section: A Target Descriptionmentioning

confidence: 99%

“…During the last decade, many research groups have been developing bright, multi-keV x-ray sources [12][13][14][15][16][17][18][19][20][21][22][23][24] . The goal has been to create millimeter-scale, homogeneous, keV-scale-temperature plasmas that are efficient laser-to-x-ray converters.…”

Section: Introductionmentioning

confidence: 99%

Multi-keV x-ray source development experiments on the National Ignition Facility

et al. 2010

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We report results from a five shot campaign carried out with Ar-Xe gas-filled targets at the National Ignition Facility (NIF). The targets were shot with ≈ 350 kJ of 3ω laser energy delivered with a 5 ns trapezoidal laser pulse. We report measured x-ray output from the target in different spectral bands both below and above 1.5 keV photon energies: we find yields of ≈20.5 kJ/sr with peak x-ray power approaching 4 TW/sr over all energies, as measured for the unique viewing angle of our detector, and ≈3.6 kJ/sr with peak x-ray power of 1 TW/sr for x rays with energies >3 keV. This is a laser-to-x-ray conversion efficiency of 13±1.3 % for isotropic x rays with energies >3 keV. Laser energy reflected by the target plasma for both inner and outer-cone beams is measured and found to be small, between 1-4% of the drive energy. The energy emitted in hard x rays (with energies >25 keV) is measured and found to be ≈1 J/sr. Two-dimensional imaging of the target plasma during the laser pulse confirms a fast, volumetric heating of the entire target, resulting in efficient laser-to-x-ray conversion. Post-shot simulations with a two-dimensional radiation-hydrodynamics code reproduce well the observed x-ray flux and fluence, backscattered light, and bulk target motion.

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“…Lowdensity targets, which allow full volumetric heating of the emitting material by the laser, is one of them. Our group has demonstrated CE's for x-ray energies > 2 keV from 1 to 10 % using pre-exploded foils 2,3 , metal-doped aerogels 4,5 , metal oxide nanofiber 6 , and gas-filled 7,8 targets. Shaped targets, which confine, collect and allow further heating of low-density plasmas ablated from solid target walls, can also substantially increase x-ray conversion efficiency; foil-lined holhraums and halfraums demonstrated CEs of up to 7% 9,10 .…”

Section: Introductionmentioning

confidence: 99%

Efficient laser-induced 6-8 keV x-ray production from iron oxide aerogel and foil-lined cavity targets

et al. 2012

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The performance of new iron-based laser-driven x-ray sources has been tested at the omega laser facility for production of x rays in the 6.5 − 8.5 keV range. Two types of targets were experimentally investigated: low-density iron oxide aerogels (density 6 − 16 mg/cm 3 ) and stainless steel foil-lined cavity targets (steel thickness 1 − 5 µm). The targets were irradiated by 40 beams of the omega laser (500 J/beam, 1 ns pulse, wavelength 351 nm). All targets showed good coupling with the laser, with < 5% of the incident laser light backscattered by the resulting plasma in all cases (typically < 2.5%). The aerogel targets produced T e = 2 to 3 keV, n e = 0.12 − 0.2 critical density plasmas yielding a 40 − 60% laser-to-x-ray total conversion efficiency (1.2 − 3% in the Fe K-shell range). The foil cavity targets produced T e ∼ 2 keV, n e ∼ 0.15 critical density plasmas yielding a 60 − 75% conversion efficiency (1.6 − 2.2% in the Fe K-shell range). Time-resolved images illustrate that the volumetric heating of low-density aerogels allow them to emit a higher K-shell x-ray yield even though they contain fewer Fe atoms. However, their challenging fabrication process leads to a larger shot-to-shot variation than cavity targets.

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Efficient Multi-keV X-Ray Sources from Ti-Doped Aerogel Targets

Cited by 89 publications

References 21 publications

Bright x-ray sources from laser irradiation of foams with high concentration of Ti

Bright x-ray sources from laser irradiation of foams with high concentration of Ti

Multi-keV x-ray source development experiments on the National Ignition Facility

Efficient laser-induced 6-8 keV x-ray production from iron oxide aerogel and foil-lined cavity targets

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