Bulletin of the American Physical Society
64th Annual Meeting of the APS Division of Plasma Physics
Volume 67, Number 15
Monday–Friday, October 17–21, 2022; Spokane, Washington
Session GO06: ICF: Measurement and Diagnostic TechniquesLive Streamed
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Chair: Roberto Mancini, University of Nevada, Reno Room: Ballroom 111 C |
Tuesday, October 18, 2022 9:30AM - 9:42AM |
GO06.00001: A model of hybrid-CMOS background oscillations on NIF x-ray diagnostics Brian Hassard, Clement A Trosseille, Cassandra R Durand, Laura Robin Benedetti, Matthew S Dayton, Sabrina R Nagel Hybrid-CMOS (hCMOS) x-ray imagers are an essential component of many HED diagnostics; their nanosecond integration times and wide sensitivity to visible light, x-rays and charged particles make them a powerful, versatile sensor. However, pseudo-sinusoidal oscillations in their signal background have been previously observed, which significantly affect measurements in the presence of an early incident excitation. We discuss new characterizations of these background oscillations reinforcing prior observations of their connection to the physical sensor circuitry. In addition, we show how a refined mathematical model can be used to make predictions for the effects of these oscillations on measurements from x-ray diagnostics at the National Ignition Facility that incorporate hCMOS imagers, such as SLOS, the Single Line Of Sight camera. |
Tuesday, October 18, 2022 9:42AM - 9:54AM |
GO06.00002: Neural network denoising of high-energy-density x-ray images Joseph M Levesque, Elizabeth C Merritt, Alexander M Rasmus, Kirk A Flippo, Carlos A Di Stefano, Forrest W Doss Noise is a significant problem for x-ray images of High-Energy-Density (HED) experiments which reduces our ability to infer quantitative physical properties about the system. In these images we measure the spatially varying x-ray transmission across the system. We typically image over very short (10-100 ps) time scales, so these images are subject to significant statistical (Poisson) noise, and harder x-rays coupled with the camera response produces an additive noise. Denoising is necessary for improving the quality of these images for analysis, but the choice of filter also affects the underlying information in the image. Our goal is to measure small fluctuations in density from these images, so we want a denoiser which retains as much real information as possible. Spatially varying Poisson noise is not typically encountered in common optical images, however, so denoising methods are not usually tested for this kind of noise. We train a Deep Convolutional Neural Network (DnCNN) to denoise our experimental images, which generally performs better than others. |
Tuesday, October 18, 2022 9:54AM - 10:06AM |
GO06.00003: Analysis of hard x-ray data from "hot" hohlraums of various geometries at the National Ignition Facility Natalie Kostinski, Mark J May, William A Farmer, Richard L Berger, Marilyn B Schneider, Denise E Hinkel, Jean Jensen, Steve Johnson, Elvin R Monzon, Shon T Prisbrey A suite of hard x-ray data from “hot,” variously shaped and sized vacuum hohlraum experiments, is analyzed. These hohlraums were driven by 96 beams of the National Ignition Facility (NIF) laser, with laser pulse durations in the range of ~ 2 - 3 ns, and energies of ~ 4 - 6 kJ per beam. |
Tuesday, October 18, 2022 10:06AM - 10:18AM |
GO06.00004: MCNP Forward Modeling for Density Reconstruction of Double Shell NIF-ARC Radiography Tom Byvank, David D Meyerhofer, Paul A Keiter, Irina Sagert, David A Martinez, David S Montgomery, Eric N Loomis In the Double Shell Inertial Confinement Fusion concept, evaluating the shape asymmetry of imploding metal shells is vital for understanding energy-efficient compression and radiative losses of the thermonuclear fuel. The Monte Carlo N-Particle MCNP® code forward models radiography of Double Shell capsule implosions made using the Advanced Radiographic Capability at the National Ignition Facility. A procedure is developed using MCNP to reconstruct density profiles from the radiograph image intensity, which can help constrain our simulations (e.g. xRage). The synthetic radiographs can guide experimental design choices for optimizing radiograph contrast, signal-to-noise, and predictions for what times near stagnation may be radiographed for various inner shells (Cr, W, W-Be gradient). |
Tuesday, October 18, 2022 10:18AM - 10:30AM |
GO06.00005: Optimization of Diagnostic Configurations in the presence of Uncertainty using Bayesian Inference and Optimization Patrick F Knapp, Roshan V Joseph, William E Lewis, Jeffrey Fein, Christopher A Jennings, Brandon T Klein, Taisuke Nagayama, Marc-Andre Schaeuble, Kristian Beckwith Inferring plasma conditions from experimental data in High Energy Density Physics and Inertial Confinement Fusion experiments is a complex task. The quality of our inferences can be limited by choices we make in configuring the associated diagnostics and uncertainties in a variety of calibration data. Configuring instruments for this purpose is often guided primarily by intuition and fails to account for all known sources of uncertainty that can introduce significant bias and reduce confidence in our inferences. Here we present a method to optimize instrumental configurations using a physics-motivated example with the goal of minimizing bias and uncertainty in inferences while accounting for a variety of unknowns in the experiment and analysis. We show how Bayesian inference and Bayesian Optimization can be combined to provide a powerful and general method for optimizing diagnostic configurations and maximizing our learning from each experiment. |
Tuesday, October 18, 2022 10:30AM - 10:42AM |
GO06.00006: Direct inversion of deflectometry data using an electrostatic plasma model Jonathan R Davies, Peter V Heuer, Archie F Bott J. R. Davies, P. V Heuer |
Tuesday, October 18, 2022 10:42AM - 10:54AM |
GO06.00007: Investigation of Direct Laser Impulses as surrogates for intense x-ray encounters Eli Feinberg, Carolyn C Kuranz, Patrick L Poole, Steve J Moon, Brent E Blue, Laura Berzak Hopkins, Peter Porazik Direct Laser Impulse (DLI) is an experimental platform in which a high-power optical laser strikes a tamper material to emulate the compression wave generated by deposition of intense x-ray pulses in metal. This study presents analysis of DLI experiments on titanium alloys. Simple, flat titanium targets adhered to a tamper were subjected to a direct laser impulse on the Orion Laser at the UK’s Atomic Weapons Establishment. The motion of the rear surface of the target was measured with a PDI to determine characteristics of the resulting compression wave and the rigid motion of the sample. These data allow analysis of the wave speed, impulse, and dissipation, the laser ablation pressure, and the conversion of laser energy to mechanical energy. Supporting simulations aid in interpreting the conclusions from the data. The laser induced compression waves are compared to similar phenomena produced on the x-ray effects campaign on the NIF and to relevant flyer plate experiments. Conclusions and methods from this study will be important to a new DLI capability that is undergoing commissioning at the NIF. |
Tuesday, October 18, 2022 10:54AM - 11:06AM |
GO06.00008: Single Hit CCD Spectrometers for X-ray conversion efficiencies (revisited) Matthias Geissel, Tommy Ao, Quinn Looker, Patrick K Rambo, Christopher T Seagle, Luke Shulenburger, John L Porter Absolute conversion efficiencies from laser energy into X-rays are difficult to obtain given uncertainties in required filters and detector characteristics. A known method for measuring absolute X-ray flux is using a CCD camera that is placed far enough away and filtered well enough such that no more than one photon can be detected per pixel of the detector while maintaining precise knowledge of the attenuation. The image histogram then serves as an X-ray spectrum. However, remaining noise, fluorescence, sky-shine in ultra-intense laser experiments, and charge splitting to neighboring pixels are just a few complications that pose challenges to this diagnostic. We will present recent results with the Z-Petawatt and Z-Beamlet lasers and share observation and attempted explanation for spectral features from detector interactions that were previously unnoticed. |
Tuesday, October 18, 2022 11:06AM - 11:18AM |
GO06.00009: Development of multiframe time-gated x-ray backlighting for the Z Facility using multile laser pulse produced plasma x-ray source. Aaron Edens, Anthony P Colombo, Quinn Looker, Jeff Kellogg, Christopher S Speas, Patrick K Rambo, Robert R Speas, Ian C Smith, Michael C Jones, John L Porter X-ray radiography is a standard diagnostic used on the Z Facility to measure the dynamics of target implosions. The multi-kJ Z-Beamlet Laser (ZBL) system is used to create a pulsed x-ray source which backlights an experiment recorded on image plate. ZBL can create two angle-multiplexed laser beams that are focused to separate target positions inside the Z vacuum chamber. There is a desire to increase the number of images captured per shot, ideally from an identical angle to follow the evolution of features that can vary from shot to shot. |
Tuesday, October 18, 2022 11:18AM - 11:30AM |
GO06.00010: Investigation of X pinch wire array experiments on UNM’s Lobo LTD Robert Beattie-Rossberg, Salvador Portillo The University of New Mexico has begun conducting exploding wire array experiments using our 12 brick LOBO Linear transformer driver. Multiple wire arrays are studied including single wire tungsten z pinches and multiple wire tungsten x pinches. Preliminary Mach Zehnder interferometry is fielded to give density information as well as spectroscopy for density and temperature information. Rogowski coil produced current and rise time will be discussed and open shutter images as well as gated ccd images shown. Results of multiple diagnostics and their requisite analysis will be discussed along with current and future experiments. |
Tuesday, October 18, 2022 11:30AM - 11:42AM |
GO06.00011: Investigating the formation of micropinches using L-shell time-resolved spectroscopy Ahmed T Elshafiey, Nate Chalmers, Sergei Pikuz, Tatiana Shelkovenko, David A Hammer The results of L-shell spectroscopic analyses of Hybrid X-pinches (HXPs) employing an X-ray streak camera with a 10ps time resolution are presented. The goal of these experiments is to determine the plasma properties throughout the formation process of the X-pinch bright X-ray spots (hotspots). The most studied radiation from hotspots is K-shell radiation, although as previously demonstrated using streak cameras, K-shell radiation begins with a strong continuum followed by emission lines, which occur during the moment of maximum compression and the expansion phase respectively. L-shell radiation can occur earlier in time as the temperature and density requirements are substantially lower, hence they can be used to shine a light on the early compression phase before maximum compression is reached. The experiments were conducted using the XP pulsed power machine with a current of 300-350kA and a rise time of 50ns. A variety of diagnostics in addition to a streaked X-ray spectrograph, including silicon diodes and PCDs, which were used to examine the L and K-shell emissions in time using an 8Ghz oscilloscope. |
Tuesday, October 18, 2022 11:42AM - 11:54AM |
GO06.00012: Effect of high order spectral phase shaping of ultra-intense laser pulses on X-ray generation Ghassan Zeraouli, Derek A Mariscal, Paul C Campbell, Elizabeth S Grace, Graeme G Scott, Kelly K Swanson, Raspberry A Simpson, Blagoje Z Djordjevic, Ryan Nedbailo, Jaebum Park, Bryan Sullivan, Reed C Hollinger, Shoujun Wang, Jorge J Rocca, Tammy Ma Although the generation of ultra-intense laser pulses (>1020 W.cm-2) has become routine for many high intensity laser facilities around the world, optimizing the generation of laser-driven charged particles and x-rays from their interaction with solid matter is still a challenging process. Pulse energy, duration and chirp are usually the main laser parameters that are varied when carrying out studies of this type. Here, we investigate the systematic modification of high order spectral phase to produce varying pulse shapes of ultra-intense laser pulses and study their effects on the acceleration of charged particles and x-rays. |
Tuesday, October 18, 2022 11:54AM - 12:06PM |
GO06.00013: Commissioning of the General Atomics LAboratory for Developing Rep-rated Instrumentation and Experiments with Lasers (GALADRIEL) Mario Manuel, Gilbert W Collins, Christopher McGuffey, Alicia Dautt-Silva, Devin Vollmer, Brian Sammuli, Martin Margo, Mike R Jaris Present and future lasers used for studying high-energy-density (HED) physics and inertial fusion energy (IFE) will operate at repetition rates of ~0.1-10Hz. However, most diagnostics and target-fielding strategies presently implemented at single-shot facilities require breaking vacuum between shots to exchange film-media and replace a stalked target; an experimental paradigm that must change as the community moves to rep-rated operation. The GALADRIEL facility will serve as a test bed to enable rapid development and testing of rep-rated technologies, including diagnostics, targetry, data management, and control systems. GALADRIEL is built around a commercial ~1TW (~20fs, ~25mJ, 800nm) Ti:Sapph laser that is capable of up to 10Hz operation. Commissioning experiments implement a gas-jet target to generate ~MeV electrons through the laser-wakefield acceleration scheme. Initial rep-ratable diagnostics to characterize the laser-plasma interaction include a magnet-based electron spectrometer and the path-integrated density using a Shack-Hartmann wavefront sensor. Recent results will be presented along with current and future capabilities of the GALADRIEL facility. |
Tuesday, October 18, 2022 12:06PM - 12:18PM |
GO06.00014: Development of Neural Networks for Rapid Analysis of a High Repetition Rate X-Ray Diagnostic Paul C Campbell, Ghassan Zeraouli, Elizabeth S Grace, Graeme G Scott, Kelly K Swanson, Raspberry A Simpson, Blagoje Z Djordjevic, Ryan Nedbailo, Jaebum Park, Reed C Hollinger, Bryan Sullivan, Shoujun Wang, Jorge J Rocca, Tammy Ma, Derek A Mariscal Many high repetition rate capable (0.1 – 10 Hz) PW-class laser facilities now operate across the world. While these facilities can produce data at high rates, conventional diagnostics and their accompanying on-shot data analysis techniques are not able to keep up. For this reason, it would be beneficial to automate the data analysis with algorithms that can keep up with the high repetition rate of these facilities while maintaining accuracy on par with traditional analysis. Neural networks (NN) have been used in a variety of fields to analyze large data sets and have been useful for problems of image classification, object recognition, natural language processing, and more recently data analysis from scientific experiments. Here we present results on training a NN to analyze data from UCXS (Ultra-Compact X-ray Spectrometer). UCXS is a high-repetition-rate diagnostic that uses a combination of step-wedge and ross pair filtration that operates in the soft X-ray regime (1 keV - 25 keV) to determine parameters such as plasma temperature. In this presentation, we will discuss preparation of synthetic datasets for initial NN training, the development of deep and convolutional NN's, and the performance on experimental data.* |
Tuesday, October 18, 2022 12:18PM - 12:30PM |
GO06.00015: Monochromatic Talbot-Lau X-ray Imaging Diagnostics Maria Pia Valdivia Leiva, Victorien Bouffetier, Gabriel Perez-Callejo, Christian Stoeckl, T. Filkins, Chad Mileham, Mark Romanofsky, Ildar Begishev, Alexis Casner, Dan Stutman, Maria Pia Valdivia Leiva Talbot-Lau X-ray Interferometry is a refraction-based imaging technique that can characterize high electron density gradients in High Energy Density (HED) experiments through phase-contrast methods. In the Talbot-Lau X-ray Deflectometry (TXD) mode, the diagnostic delivers simultaneous attenuation, dark-field, and phase-change measurements from a single Moiré image. TXD diagnostic platforms have been deployed at the Multi-TeraWatt and Omega EP lasers using laser-produced x-ray backlighters. To further improve diagnostic performance and data accuracy, monochromatic TXD has been established using 8 keV multilayer mirrors. Copper foil and wire targets were irradiated at 1014-15 W/cm2, exploring the effect of laser pulse length (~10-80 ps) and backlighter target configuration on spatial resolution and Moiré fringe contrast. Copper foils irradiated at 80° delivered <6 µm spatial resolution with increased fringe contrast (>30%) in comparison with previous results using standard TXD diagnostics (11-24%). Additionally, advanced data post-processing tools have been developed to enhance TXD diagnostic capabilities. Instrumental and experimental limitations for monochromatic TXD diagnostics in the laser environment will be presented and discussed. |
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