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Sutcliffe, G.

Publications and source records attributed to Sutcliffe, G..

11 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Measuring stopping power in warm dense matter plasmas at OMEGA

A platform has been developed for accurately measuring the stopping power of high energy protons through warm dense matter (WDM) plasmas characterized by x-ray Thomson scattering. Here, in this work, stopping power measurements were successfully made through both WDM Beryllium and Boron plasmas. In the Boron experiments, an increase in stopping was observed over their cold target counter-parts. This increase in stopping was shown to agree well with models that account for the partial ionization of the plasma.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2021

Extension of charged-particle spectrometer capabilities for diagnosing implosions on OMEGA, Z, and the NIF

New designs and a new analysis technique have been developed for an existing compact charged-particle spectrometer on the NIF and OMEGA. The new analysis technique extends the capabilities of this diagnostic to measure arbitrarily shaped ion spectra down to 1 MeV with yields as low as 10 6 . Three different designs are provided optimized for the measurement of DD protons, T 3 He deuterons, and 3 He 3 He protons. The designs are highly customizable, and a generalized framework is provided for optimizing the design for alternative applications. Additionally, the understanding of the detector’s response and uncertainties is greatly expanded upon. A new calibration procedure is also developed to increase the precision of the measurements.

47 OTHER INSTRUMENTATION↗
DOE OSTI2021

Response of CR-39 nuclear track detectors to protons with non-normal incidence

This paper presents data from experiments with protons at non-normal incidence to CR-39 nuclear track detectors, analyzing the properties of detection efficiency, proton track diameter, track contrast, and track eccentricity. Understanding the CR-39 response to protons incident at an angle is important for designing charged particle detectors for inertial confinement fusion (ICF) applications. This study considers protons with incident energies less than 3 MeV. In this regime, an incident angle of 10° has no effect on CR-39 detection efficiency, and >85% detection efficiency is preserved up through 25° in the range of 1.0 MeV–2.1 MeV. For ICF applications, incident angles above 30° are deemed impractical for detector design due to significant drops in proton detection at all energies. We observe significant reductions in detection efficiency compared to theoretical predictions, particularly at low energies where proton tracks are etched away. The proton track diameter measured by the scan system is observed to decrease with higher incident angles. The track diameters are analyzed with two fitting models, and it is shown that the diameter–energy relation can be fit with the existing models at angles up to 30°. The optical contrast of the tracks tends to increase with the angle, meaning that the tracks are fainter, and a larger increase is observed for higher energies. Eccentricity, a measure of how elongated proton tracks are, increases with the incident angle and drops after the critical angle. The lowest energy tracks remain nearly circular even at higher angles.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2021

Characterizing x-ray transmission through filters used in high energy density physics diagnostics

We report on the design and implementation of a new system used to characterize the energy-dependent x-ray transmission curve, Θ(E), through filters used in high-energy density physics diagnostics. Using an Amptek X-123-CdTe x-ray spectrometer together with a partially depleted silicon surface barrier detector, both the energy spectrum and total emission of an x-ray source have been accurately measured. By coupling these detectors with a custom PROTO-XRD x-ray source with interchangeable cathodes, accurate characterizations of Θ(E) for filters of varying materials and thicknesses have been obtained. The validity of the technique has been confirmed by accurately reproducing areal densities for high-purity filters with known x-ray transmission properties. In this paper, the experimental setup is described and the results of absorption calibrations performed on a variety of different filters are presented.

Pearcy, J.↗
DOE OSTI2021

Characterizing x-ray transmission through filters used in high energy density physics diagnostics

We report on the design and implementation of a new system used to characterize the energy-dependent x-ray transmission curve, Θ(E), through filters used in high-energy density physics diagnostics. Using an Amptek X-123-CdTe x-ray spectrometer together with a partially depleted silicon surface barrier detector, both the energy spectrum and total emission of an x-ray source have been accurately measured. By coupling these detectors with a custom PROTO-XRD x-ray source with interchangeable cathodes, accurate characterizations of Θ(E) for filters of varying materials and thicknesses have been obtained. The validity of the technique has been confirmed by accurately reproducing areal densities for high-purity filters with known x-ray transmission properties. In this paper, the experimental setup is described and the results of absorption calibrations performed on a variety of different filters are presented.

47 OTHER INSTRUMENTATION↗
DOE OSTI2021

Response of CR-39 nuclear track detectors to protons with non-normal incidence

This paper presents data from experiments with protons at non-normal incidence to CR-39 nuclear track detectors, analyzing the properties of detection efficiency, proton track diameter, track contrast, and track eccentricity. Understanding the CR-39 response to protons incident at an angle is important for designing charged particle detectors for inertial confinement fusion (ICF) applications. This study considers protons with incident energies less than 3 MeV. In this regime, an incident angle of 10° has no effect on CR-39 detection efficiency, and >85% detection efficiency is preserved up through 25° in the range of 1.0 MeV–2.1 MeV. For ICF applications, incident angles above 30° are deemed impractical for detector design due to significant drops in proton detection at all energies. We observe significant reductions in detection efficiency compared to theoretical predictions, particularly at low energies where proton tracks are etched away. The proton track diameter measured by the scan system is observed to decrease with higher incident angles. The track diameters are analyzed with two fitting models, and it is shown that the diameter–energy relation can be fit with the existing models at angles up to 30° . The optical contrast of the tracks tends to increase with the angle, meaning that the tracks are fainter, and a larger increase is observed for higher energies. Eccentricity, a measure of how elongated proton tracks are, increases with the incident angle and drops after the critical angle. The lowest energy tracks remain nearly circular even at higher angles.

47 OTHER INSTRUMENTATION↗
DOE OSTI2020

CR-39 nuclear track detector response to inertial confinement fusion relevant ions

The detection properties of CR-39 were investigated for protons, deuterons, and tritons of various energies. Two models for the relationship between the track diameter and particle energy are presented and demonstrated to match experimental data for all three species. Data demonstrate that CR-39 has 100% efficiency for protons between 1 MeV and 4 MeV, deuterons between 1 MeV and 12.2 MeV, and tritons between 1 MeV and 10 MeV. The true upper bounds for deuterons and tritons exceed what could be measured in data. Simulations were developed to further explore the properties of CR-39 and suggest that the diameter–energy relationship of alpha particles cannot be captured by the conventional c-parameter model. These findings provide confidence in CR-39 track diameter based spectroscopy of all three species and provide invaluable insight for designing filtering for all CR-39 based diagnostics.

47 OTHER INSTRUMENTATION↗
DOE OSTI2018

Characterizing plasma conditions in radiatively heated solid-density samples with x-ray Thomson scattering

Here, we have developed an experimental platform to generate radiatively heated solid density samples for warm dense matter studies at the OMEGA laser facility. Cylindrical samples of boron and beryllium are isochorically heated by K- and L-shell emission from x-ray converter foils wrapped around the cylinders' radii. X-ray Thomson scattering (XRTS) measures the temperature and the ionization state of the samples as function of time. Temperatures approach 10 eV, and the ionization states are found to be Z B = 3 and Z Be = 2. Radiation hydrodynamics simulations were performed to confirm a homogeneous plasma state exists in the center of the sample for the duration of the experiment. Results from the study can be extended to improve understanding of radiative heating processes in the warm dense matter regime.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2016

A Particle X-ray Temporal Diagnostic (PXTD) for studies of kinetic, multi-ion effects, and ion-electron equilibration rates in Inertial Confinement Fusion plasmas at OMEGA (invited)

Here, a Particle X-ray Temporal Diagnostic (PXTD) has been implemented on OMEGA for simultaneous time-resolved measurements of several nuclear products as well as the x-ray continuum produced in High Energy Density Plasmas and Inertial Confinement Fusion implosions. The PXTD removes systematic timing uncertainties typically introduced by using multiple instruments, and it has been used to measure DD, DT, D 3 He, and T 3 He reaction histories and the emission history of the x-ray core continuum with relative timing uncertainties within ±10-20 ps. This enables, for the first time, accurate and simultaneous measurements of the x-ray emission histories, nuclear reaction histories, their time differences, and measurements of T i (t) and T e (t) from which an assessment of multiple-ion-fluid effects, kinetic effects during the shock-burn phase, and ion-electron equilibration rates can be made.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗