Calibrating of x-ray detectors in the 8 to 111 keV energy range and their application to diagnostics on the National Ignition Facility

Lee, Joshua J.; Haugh, M. J.; LaCaille, Greg; Torres, Peter

doi:10.1117/12.930162

Cited by 6 publications

(2 citation statements)

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“…The high-energy x-ray source (HEX) at NSTec Livermore Operations served as a calibration source. 11 HEX uses a high-energy x-ray tube to excite K-shell fluorescence in a fluorescer foil and is capable of delivering near monoenergetic x-ray energies in the range of 8 keV (Cu K α ) to 111 keV (U K β ). The x-ray emission is collimated and its total flux is measured with an absolutely calibrated, energy-dispersive high-purity germanium detector (HPGe).…”

Section: Characterizationmentioning

confidence: 99%

Measuring the hot-electron population using time-resolved hard x-ray detectors on the NIF

et al. 2013

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In laser-driven inertial confinement fusion, hot electrons can preheat the fuel and prevent compression of the capsule to ignition conditions. Measuring the hot-electron population in these high-intensity, laser-driven experiments is key to understanding the laser-plasma interaction and the resulting target evolution. This can be inferred from the bremsstrahlung generated by the interaction of the hot electrons with the target. At the National Ignition Facility (NIF), the filter-fluorescer x-ray diagnostic (FFLEX), a multichannel, hard x-ray spectrometer operating in the 20-to 500-keV range, was recently upgraded to provide time-resolved measurements of the bremsstrahlung spectrum. Characterization data is presented for the upgraded setup, as well as recent results from ignition-scale experiments.

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Section: Characterizationmentioning

confidence: 99%

Measuring the hot-electron population using time-resolved hard x-ray detectors on the NIF

et al. 2013

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“…Additionally, the relative strength of the signal from SPIDER gives an indication of the quality of the experimental parameters. In order to increase the significance of the measurements from SPIDER, the absolute characterization of the spectral sensitivity was executed at the High Energy X-ray (HEX) lab [7] at the National Security and Technologies, LLC (NSTec) Livermore facility. A determination of the absolute x-ray yield would be useful in several ways: (1) To gauge the relative quality of implosions or back-lighter strength among NIF experiments; (2) as an input parameter into a model that estimates the amount of material mixing that occurs from the capsule outer shell into the fuel layers of the DT capsule [8]; (3) If the x-ray yield is predicted for a particular experiment, then appropriate filtering can be chosen for SPIDER to optimize the dynamic range of the recorded signal.…”

Section: Introductionmentioning

confidence: 99%

Characterization of the x-ray sensitivity of a streak camera used at the National Ignition Facility (NIF)

et al. 2013

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A neutron hardened x-ray streak camera has been used to report x-ray burn duration and time of peak emission from imploding ICF capsules at the National Ignition Facility with  <30 ps. Recent characterization of the instrument using a NIST traceable High Energy X-ray reference source (HEX, National Security Technologies) will enable absolute capsule self-emission x-ray yield measurements (J/sr/keV). This manuscript describes the characterization procedure used and preliminary results of the x-ray sensitivity using three different thicknesses of the CsI photocathode.

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Time-resolved measurements of the hot-electron population in ignition-scale experiments on the National Ignition Facility (invited)

Hohenberger

Albert

Palmer

et al. 2014

Review of Scientific Instruments

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In laser-driven inertial confinement fusion, hot electrons can preheat the fuel and prevent fusion-pellet compression to ignition conditions. Measuring the hot-electron population is key to designing an optimized ignition platform. The hot electrons in these high-intensity, laser-driven experiments, created via laser-plasma interactions, can be inferred from the bremsstrahlung generated by hot electrons interacting with the target. At the National Ignition Facility (NIF) [G. H. Miller, E. I. Moses, and C. R. Wuest, Opt. Eng. 43, 2841 (2004)], the filter-fluorescer x-ray (FFLEX) diagnostic-a multichannel, hard x-ray spectrometer operating in the 20-500 keV range-has been upgraded to provide fully time-resolved, absolute measurements of the bremsstrahlung spectrum with ∼300 ps resolution. Initial time-resolved data exhibited significant background and low signal-to-noise ratio, leading to a redesign of the FFLEX housing and enhanced shielding around the detector. The FFLEX x-ray sensitivity was characterized with an absolutely calibrated, energy-dispersive high-purity germanium detector using the high-energy x-ray source at NSTec Livermore Operations over a range of K-shell fluorescence energies up to 111 keV (U Kβ). The detectors impulse response function was measured in situ on NIF short-pulse (∼90 ps) experiments, and in off-line tests.

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Calibrating of x-ray detectors in the 8 to 111 keV energy range and their application to diagnostics on the National Ignition Facility

Cited by 6 publications

References 0 publications

Measuring the hot-electron population using time-resolved hard x-ray detectors on the NIF

Measuring the hot-electron population using time-resolved hard x-ray detectors on the NIF

Characterization of the x-ray sensitivity of a streak camera used at the National Ignition Facility (NIF)

Time-resolved measurements of the hot-electron population in ignition-scale experiments on the National Ignition Facility (invited)

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