Bulletin of the American Physical Society
62nd Annual Meeting of the APS Division of Plasma Physics
Volume 65, Number 11
Monday–Friday, November 9–13, 2020; Remote; Time Zone: Central Standard Time, USA
Session NP13: Poster Session: ICF: Diagnostics (9:30pm - 12:30pm)On Demand
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NP13.00001: Radiation generated by magnetized plasma dipole oscillation in a non-uniform plasma Hyung Seon Song, Kylychbekov Salizhan, MinSup Hur We investigate the properties of Plasma Dipole Oscillation (PDO) in a magnetic field by particle-in-cell (PIC) simulations. By colliding two detuned laser pulses, an isolated, oscillating lump of electrons (i.e. PDO) is produced in the plasma. The oscillation mechanism of PDO is the plasma oscillation and hence, the PDO oscillates with the plasma frequency. When the PDO is magnetized by an external magnetic field aligned perpendicular to the PDO oscillation, the frequency of PDO splits into the left and right cut-offs of the X-mode. By two- and three-dimensional particle-in-cell simulations, we demonstrate that the two cut-off frequencies are imprinted to the radiation emitted from the PDO. Hence the PDO-radiation can be used for simultaneous probe of magnetic field and the plasma density of a non-uniform magnetized plasma. We discuss the decay and diffraction of the R- and L-cutoff radiations, for utilization of the technique for a novel diagnostic method of a magnetized plasma [Preview Abstract] |
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NP13.00002: Diagnostics for gas puff experiments on~a~Linear Transformer Driver (CESZAR) Apsara Williams, Fabio Conti, Vladimir Fadeev, Jeffrey Narkis, Gil Collins, Nicholas Aybar, Farhat Beg The CESZAR is a low inductance compact (2m diameter) pulsed-power generator designed to provide up to 1MA of current in 160ns. First experiments on the generator are carried out with a hollow single shell~Ar~gas puff, with the goal of measuring the energy coupling in a low inductance system.The diagnostic suite on these experiments includes filtered photodiodes, laser schlieren imaging and interferometry, spectroscopy, and time-gated XUV pinhole imaging. The temperature and density information is extracted to determine energy coupling. A comparison of experimental results with MHD modeling will be presented to show energy coupling in low inductance system. [Preview Abstract] |
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NP13.00003: An Ultra Portable X-Pinch for Probing Warm Dense Matter S N Bland, B Krawczyk, T Gheorghiu, S Parker, N Schwartz, J Strucka, S Theocharous, J Yan, Z Zhao Determining the properties of Warm Dense Matter (WDM) necessitates the use of advanced X-ray based diagnostics including diffraction and absorption spectrometry. As many experiments that produce WDM do so for only a few ns, the probing X-rays must be short pulsed, ideally with a high enough yield to produce data on a single experiment. They must also have the correct spectral characteristics – e.g. having a smooth continuum for absorption spectrometry. Such requirements often restrict experiments to large scale facilities like 3rd generation Synchrotrons and XFELs, which have exemplary capabilities, but can also have very limited time available. At Imperial College we have been developing several X-pinch based X-ray sources to provide a complementary capability to large facilities, with the aim of promoting ‘in house’ WDM research at Universities. We report initial results from our latest X-pinch system “Dry Pinch 2” that is extremely portable and made so that any researcher can use it with minimal training. From the outset Dry Pinch 2 has been designed to be easy to build and includes advanced features such as solid state triggering and inbuilt HV charging. It can utilize loads including an embedded gas jet that may negate the need for reloading wires in between experiments [Preview Abstract] |
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NP13.00004: A Portable X-pinch Source for Dispersive X-ray Absorption Spectroscopy Jergus Strucka, Simon Bland, Bartosz Krawczyk, Savva Theocharous, Jiaqi Yan, Zijian Zhao Dynamic compression experiments on pulsed-power machines produce more uniform extreme states of matter that can reach mm in size. It is of interest to material science and planetary science to study the phase transitions and long-range structure in these extreme states. Recently, X-ray sources of high fluence and short pulse duration have been used in dispersive geometry to employ X-ray absorption fine structure spectroscopy as an ideal element-specific structural probe. These experiments are traditionally driven by (inter)national scale laser facilities, and more recently synchrotrons$^{\mathrm{.}}$ Our next generation portable X-pinch driver -- Dry Pinch 1 -- is only 30cm x 70cm, weight @50kg and produces \textgreater 100kA currents in a few 100ns pulse. The X-pinch emits \textasciitilde 100mJ of radiation \textgreater 10KeV, directly comparable to 3$^{\mathrm{rd}}$ generation synchrotron at a distance of \textless 20cm from the pinch. Dry pinch 1 is ideally suited as a complementary source for optimization of experimental setups before high-precision campaigns at large facilities. I will present the recent developments, preliminary results, and future milestones in our spectroscopy campaign. [Preview Abstract] |
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NP13.00005: New X-Pinch Platform and Faraday Rotation Diagnostic for the MAIZE Pulsed Power Facility George V Dowhan, Nicholas M Jordan, Simon N Bland, Sergei V Lebedev, Rowland A Smith, Lee Suttle, Ryan D McBride X-pinches, formed by driving intense current through the crossing of 2 or more wires, provide an excellent platform for the study of ``micro-pinches'' due to their propensity to generate a single micro-pinch at a predetermined location in space (i.e., where the wires cross). Ideally, micro-pinches compress to very small radii (\textasciitilde 1 \textmu m) leading to pressures on the order of \textasciitilde 1 Gbar for currents on the order of \textasciitilde 0.1 MA. However, the fraction of the total current that is driven through the dense micro-pinch plasma at small radii versus that being shunted through the surrounding coronal plasma at larger radii is not well known. To allow for the study of micro-pinches and their current distribution on the 1-MA MAIZE facility, an imaging Faraday rotation diagnostic, as well as corresponding X-pinch load hardware, were developed. Presented are preliminary experimental results investigating the current distribution in various multi-wire X-pinches as well as hybrid X-pinches. This work was supported by the DOE Early Career Research Program under Grant DE-SC0020239 and by the NNSA SSAP under Cooperative Agreement DE-NA0003764. [Preview Abstract] |
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NP13.00006: Experimental Validation of Gamma Reaction History (GRH) Response to Neutron Induced Gamma Rays Yongho Kim, Kevin Meaney, Hermann Geppert-Kleinrath, Hans Herrmann, Mike Rubery, Alex Leatherland The Gamma Reaction History (GRH) diagnostic has provided a fusion reaction history at the National Ignition Facility (NIF) by detecting a 16.75 MeV gamma ray generated from deuterium-tritium (DT) fusion reactions. Two gas cells of the GRH detector typically operate at 10 MeV or 8 MeV energy thresholds to isolate the DT fusion gammas, however, the GRH signal may be contaminated by various neutron-induced gammas such as (1) imploding capsules (e.g., C or SiO2), (2) hohlraum (e.g., Au or U), and (3) thermo-mechanical package (e.g., Si or Al). Experimental validation of the GRH response to the neutron-induced gamma rays is necessary to reduce uncertainty in the measurement of the fusion reaction history. Elemental samples of C, Si, Al, and W were irradiated with 14 MeV DT fusion neutrons at the OMEGA Laser Facility and their resulting gamma emission was measured. The Geant4 Monte-Carlo simulation will be compared with experimental measurements to validate a neutron-induced gamma production and a GRH detector response. [Preview Abstract] |
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NP13.00007: Quantifying the effects of neutron scattering for neutron yield isotropy measurements at the NIF K. D. Hahn, R. M. Bionta, H. Khater, E. A. Henry, A. S. Moore, D. J. Schlossberg, D. A. Barker, E. R. Casco, R. B. Ehrlich, J. M. Gjemso, A. B. Golod, G. P. Grim, E. P. Hartouni, S. M. Kerr The neutron yield diagnostics at the NIF have been upgraded to include 48 detectors placed around the NIF target chamber to assess the DT neutron yield isotropy for inertial confinement fusion experiments. The real-time neutron-activation detectors (RT-NADs) are used to understand yield asymmetries due to variations in the fuel and ablator areal densities, Doppler shifts in the neutron energy due to hotspot motion, and other physics effects. In order to isolate target physics effects, we must understand the contribution due to neutron scattering associated with the different hardware configurations used for each experiment. Our goal is to achieve 1{\%} or better precision in determining the yield isotropy. We present Monte Carlo simulations and experimental measurements to quantify this impact. [Preview Abstract] |
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NP13.00008: K-shell radiation from Krypton Doped Symmetric Capsule Implosion Experiments on NIF Nicholas Ouart, Arati Dasgupta, Marilyn Schneider, Howard Scott, Robert Kauffman, Daniel Thorn, Andrew MacPhee, Lan Gao, Kenneth Hill, Brian Kraus, Manfred Bitter, Philip Efthimion X-ray spectroscopy is used to diagnose plasma conditions of a symmetric capsule (symcap) target in ICF experiments on NIF. Small traces of krypton were added as a dopant to the deuterium gas inside the symcap target. The high areal density shell of the symcap target has minimal attenuation of the krypton K-shell emission. The fraction of krypton dopant was selected to minimally perturb the implosion, but large enough to be measured[1,2]. The krypton He-alpha and He-beta line emission was measured using the absolutely calibrated dHIRES built by PPPL[3]. Synthetic spectra generated from the NRL DRACHMA II code will be used to model the radiation to infer the plasma conditions. Drachma is a 1-D multi-zone non-LTE kinetics model with radiation transport. [1] T. Ma \textit{et al.,} RSI 87, 11E327 (2016) [2] H. Chen, T. Ma, R. Nora, et al, Phys Plasmas 24. 072715 (2017) [3] L. Gao \textit{et al.}, RSI \textbf{89}, 10F125 (2018) *Work supported by DOE/NNSA at NRL and U.S. DOE by LLNL under Contract No. DE-AC52-07NA27344. DISTRIBUTION A. Approved for public release: distribution unlimited. [Preview Abstract] |
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NP13.00009: Modern regularization methods for deblurring and denoising in ICF D.S. Montgomery, P.A. Keiter, J.P. Sauppe Radiographic images in ICF are often characterized as being noisy and blurry. While substantial enhancements have been made in the past couple of decades to improve the spatial resolution and photon collection efficiency of X-ray imaging instruments, we are limited still to resolving only lower mode spatial structures degraded by spatial blur. Meanwhile, modern mathematical methods have been developed and applied in the medical imaging, satellite imaging, astronomy, and other communities relying on image data to robustly remove noise and image blur as a class of ill-posed inverse problems using regularization to ensure the recovered image is well behaved when information is lost from noise and blur, and use of prior information is enforced. Such methods have enabled super-resolution to be achieved in single frame images, as well as other advanced image recovery techniques. In this poster we will give a brief, high level review of the math techniques used, their applications to other areas of imaging, and initial application to ICF synthetic radiographs and NIF X-ray experimental data. [Preview Abstract] |
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