Engineering topics

Huntington, C.

Publications and source records attributed to Huntington, C..

7 records

DOE OSTI2016

Proton pinhole imaging on the National Ignition Facility

Pinhole imaging of large (mm scale) carbon-deuterium (CD) plasmas by proton self-emission has been used for the first time to study the microphysics of shock formation, which is of astrophysical relevance. The 3 MeV deuterium-deuterium (DD) fusion proton self-emission from these plasmas is imaged using a novel pinhole imaging system, with up to five different 1 mm diameter pinholes positioned 25 cm from target-chamber center. CR39 is used as the detector medium, positioned at 100 cm distance from the pinhole for a magnification of 4 ×. A Wiener deconvolution algorithm is numerically demonstrated and used to interpret the images. When the spatial morphology is known, this algorithm accurately reproduces the size of features larger than about half the pinhole diameter. For these astrophysical plasma experiments on the National Ignition Facility, this provides a strong constraint on simulation modeling of the experiment.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

DOE OSTI2016

eHXI: A permanently installed, hard x-ray imager for the National Ignition Facility

We have designed and built a multi-pinhole imaging system for high energy x-rays (≥ 50 keV) that is permanently installed in the equatorial plane outside of the target chamber at the National Ignition Facility (NIF). It records absolutely-calibrated, time-integrated x-ray images with the same line-of-sight as the multi-channel, spatially integrating hard x-ray detector FFLEX [McDonald et al., Rev. Sci. Instrum. 75 (2004) 3753], having a side view of indirect-drive inertial confinement fusion (ICF) implosion targets. The equatorial hard x-ray imager (eHXI) has recorded images on the majority of ICF implosion experiments since May 2011. Lastly, eHXI provides valuable information on hot electron distribution in hohlraum experiments, target alignment, potential hohlraum drive asymmetries and serves as a long term reference for the FFLEX diagnostics.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

DOE OSTI2016

Proton imaging of an electrostatic field structure formed in laser-produced counter-streaming plasmas

Here, we report the measurements of electrostatic field structures associated with an electrostatic shock formed in laser-produced counter-streaming plasmas with proton imaging. The thickness of the electrostatic structure is estimated from proton images with different proton kinetic energies from 4.7 MeV to 10.7 MeV. The width of the transition region is characterized by electron scale length in the laser-produced plasma, suggesting that the field structure is formed due to a collisionless electrostatic shock.

42 ENGINEERING↗

DOE OSTI2014

X-ray area backlighter development at the National Ignition Facility (invited)

1D spectral imaging was used to characterize the K-shell emission of Z ≈ 30–35 and Z ≈ 40–42 laser-irradiated foils at the National Ignition Facility. Foils were driven with up to 60 kJ of 3ω light, reaching laser irradiances on target between 0.5 and 20 × 10{sup 15} W/cm{sup 2}. Laser-to-X-ray conversion efficiency (CE) into the He{sub α} line (plus satellite emission) of 1.0%–1.5% and 0.15%–0.2% was measured for Z ≈ 30–32 and Z ≈ 40–42, respectively. Measured CE into He{sub α} (plus satellite emission) of Br (Z = 35) compound foils (either KBr or RbBr) ranged between 0.16% and 0.29%. Measured spectra are compared with 1D non-local thermodynamic equilibrium atomic kinetic and radiation transport simulations, providing a fast and accurate predictive capability.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

DOE OSTI2014

FY14 LLNL OMEGA Experimental Programs

In FY14, LLNL’s High-Energy-Density Physics (HED) and Indirect Drive Inertial Confinement Fusion (ICF-ID) programs conducted several campaigns on the OMEGA laser system and on the EP laser system, as well as campaigns that used the OMEGA and EP beams jointly. Overall these LLNL programs led 324 target shots in FY14, with 246 shots using just the OMEGA laser system, 62 shots using just the EP laser system, and 16 Joint shots using Omega and EP together. Approximately 31% of the total number of shots (62 OMEGA shots, 42 EP shots) shots supported the Indirect Drive Inertial Confinement Fusion Campaign (ICF-ID). The remaining 69% (200 OMEGA shots and 36 EP shots, including the 16 Joint shots) were dedicated to experiments for High- Energy-Density Physics (HED). Highlights of the various HED and ICF campaigns are summarized in the following reports.

36 MATERIALS SCIENCE↗

DOE OSTI2013

Ag BL Description for General Atomics

The Material Strength campaign at LLNL is an effort to measure the resistance of materials to deformation when placed under large stresses. These experiments are carried out at large laser facilities, where a laser-driven plasma pusher creates a pressure in excess of 5 Mbar (on the NIF) or 1 Mbar (at OMEGA) in the sample of interest. Strong materials resist deforming in response to these high pressures, and the magnitude of the strength can be inferred using an x-ray probe traversing the sample. The x-ray source used for this probe must be bright, high-energy, and spatially coherent. To achieve all of these things, silver micro-wires and micro-flags are an essential diagnostic tool.

36 MATERIALS SCIENCE↗

DOE OSTI2013

FY13 LLNL OMEGA Experimental Programs

In FY13, LLNL’s High-Energy-Density Physics (HED) and Indirect Drive Inertial Confinement Fusion (ICF-ID) programs conducted several campaigns on the OMEGA laser system and on the EP laser system, as well as campaigns that used the OMEGA and EP beams jointly. Overall LLNL led 290 target shots involving the OMEGA laser system and 158 target shots involving the EP laser system. Approximately 34% of the total number of shots (93 OMEGA shots, 58 EP shots) shots supported the Indirect Drive Inertial Confinement Fusion Campaign (ICF-ID). The remaining 66% (197 OMEGA shots and 100 EP shots) were dedicated to experiments for High-Energy-Density Physics (HED).

36 MATERIALS SCIENCE↗