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 CO04: ICF: Compression and Burn ILive Streamed
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Chair: Ryan Sacks, LANL Room: Ballroom 111 A |
Monday, October 17, 2022 2:00PM - 2:12PM |
CO04.00001: Accomplishments of the 100-Gbar Campaign on OMEGA Sean P Regan, Valeri N Goncharov, Michael Campbell, Riccardo Betti, Kenneth Anderson, Joshua Baltazar, Daniel H Barnak, K. A Bauer, Robert Boni, Mark J Bonino, Duc Cao, Dave Canning, Kristen Churnetski, Timothy J Collins, Gilbert W Collins, Jonathan R Davies, Christophe Dorrer, Robert F Earley, Reuben Epstein, Russell K Follett, Chad J Forrest, Dustin Froula, Vladimir Y Glebov, Varchas Gopalaswamy, David R Harding, Peter V Heuer, E M Hill, Suxing Hu, Igor Igumenshchev, Steven T Ivancic, Douglas W Jacobs-Perkins, Roger T Janezic, Joe Katz, James P Knauer, Mark Labuzeta, Aarne Lees, John A Marozas, Patrick m McKenty, Samuel Morse, Philip M Nilson, John P Palastro, Dhrumir Patel, Jonathan L Peebles, P. B Radha, Hans Rinderknecht, Michael J Rosenberg, J. Ryan Rygg, Siddharth Sampat, Thomas C Sangster, Rahul C Shah, Matthew Sharpe, Walter Shmayda, Milton Shoup, Alex Shvydky, Andrey Solodov, Zaire Sprowal, Chuck Sorce, Andrew Sorce, Christian Stoeckl, Cliff A Thomas, Wolfgang R Theobald, David Turnbull, Leon Waxer, Mark Wittman, Ka Ming Woo, Jon D Zuegel, Patrick J Adrian, Johan A Frenje, Maria Gatu-Johnson, Justin H Kunimune, Brian Appelbe, Aidan C Crilly, Jason W Bates, Max Karasik, Arnaud Colaitis, Mike Farrell, Haibo Huang, Jared F Hund, Claudia M Shuldberg, Aaron M Hansen, Owen M Mannion The 100-Gbar Campaign on OMEGA investigated key aspects of laser-direct-drive inertial confinement fusion: laser power balance, fill-tube target research and development, diagnostic research and development, laser–plasma interactions (LPI's), laser imprint, laser upgrades for LPI mitigation, shock timing, 1-D implosion physics and optimization campaigns, implosion modeling and simulations, and 3-D reconstruction of the implosion. The observed increase of the stagnation pressure from 50 Gbar to 80 Gbar and a corresponding increase in the energy-scaled, generalized Lawson criterion from 0.56 to 0.8 during the campaign will be reported. The innovations spurred in machine-learning data analysis techniques based on statistical modeling, the development of laser and target solutions to mitigate implosion-degradation mechanisms, the development of 3-D diagnostics to understand implosion symmetry and the flow velocity of the fusing hot-spot plasma, and the development of next-generation, broad-bandwidth lasers to mitigate LPI and laser imprint will be highlighted. |
Monday, October 17, 2022 2:12PM - 2:24PM |
CO04.00002: Designing Parameter Scans to Better Understand, Optimize, and Extrapolate Capabilities in Laser Direct Drive Cliff A Thomas, Wolfgang R Theobald, James P Knauer, Christian Stoeckl, Michael J Rosenberg, Timothy J Collins, Valeri N Goncharov, Riccardo Betti, Edward M Campbell, Christopher Deeney, Kenneth Anderson, Joshua Baltazar, K. A Bauer, Duc Cao, Stephen Craxton, Dana H Edgell, Reuben Epstein, Chad J Forrest, Vladimir Y Glebov, Varchas Gopalaswamy, Igor Igumenshchev, Steven T Ivancic, Douglas W Jacobs-Perkins, Roger T Janezic, Tirtha R Joshi, Joe Kwiatkowski, Aarne Lees, Frederic J Marshall, Michael Michalko, Zaarah Mohamed, Dhrumir P Patel, Jonathan L Peebles, Radha Bahukutumbi, Sean P Regan, Hans Rinderknecht, Siddharth Sampat, Thomas C Sangster, Rahul C Shah, Ka Ming Woo Statistical modeling of laser-direct-drive (LDD) cryogenic implosions at OMEGA has led to fusion yields higher by a factor of 3 to 5. The potential of the technique depends on the range and repeatability of prior data and the accuracy of measurements. It might also depend on the structure of data, and its ability to inform and improve aspects of integrated simulations. Here, we present results of implosion experiments that are newly designed to simplify interpretation(s) of laser-target coupling and hydrodynamic stability. In the first set, we vary the beam-to-target radius (R = Rb/Rt) from 0.67 to 1.07; in the second, we vary the in-flight aspect ratio (IFAR) from 30 to 50. When observations are compared to the statistical model and calculations in 1-D and 2-D, they clearly demonstrate the importance of target flaws and imperfections. Combined with previous experiments on hydrodynamic scale, these data are then used to suggest new directions in parameter space with the goal of achieving multi-MJ fusion yields with a driver < ~ 1 MJ. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0003856. [1] V. Gopalaswamy et al., Nature 565, 581 (2019) [2] A. Lees et al., Phys. Rev. Lett. 127, 105001 (2021)
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Monday, October 17, 2022 2:24PM - 2:36PM |
CO04.00003: Improving performance of OMEGA direct-drive cryogenic implosions using embedded Si-doped plastic layers Pericles S Farmakis, Varchas Gopalaswamy, Aarne Lees, James P Knauer, Connor A Williams, Riccardo Betti Using Si-doped ablators in recent OMEGA DT-layered implosions has led to record neutron yields up to 3.1e14. Silicon increases collisional absorption and augments the final implosion velocity. However, radiation-hydrodynamic simulations (using LILAC) indicate that the presence of silicon enhances radiation emission from the conduction zone and coronal plasma, thereby preheating the DT ice and reducing the areal density. To reduce radiation preheat, a “sandwich” ablator has been designed where the Si-doped layer is embedded between an inner and outer layer of CD. The thicknesses of the sandwich target are chosen to optimize the laser energy absorption while minimizing radiation preheat. Only a slight decrease in the LILAC-predicted yields is observed as the amount of silicon present in the system is reduced. This controls radiative preheat and increases LILAC ρR. Simulations predicts the existence of an optimum thickness for the outer plastic layer and the embedded Si-doped layer. Increasing the thickness beyond its optimum value results in a significant reduction in neutron yield. Results from the first experiments using the sandwich targets will be presented and compared with rad-hydro simulations. |
Monday, October 17, 2022 2:36PM - 2:48PM |
CO04.00004: Experimentally Inferred Dependencies of the Ion Temperature, Areal Density, and Fusion Yield in OMEGA Direct-Drive Implosions Riccardo Betti, Varchas Gopalaswamy, Aarne Lees, James P Knauer, Connor A Williams Statistical modeling [1] of OMEGA direct-drive implosions has provided an accurate predictive capability for designing high-performance implosions achieving record neutron yields up to 3.1 x 1014. Other relevant implosion performance parameters are the ion temperature and the areal density. A physics-based statistical model [2] of the fusion yield has revealed the different dependencies of the measured neutron yield. The relevant dependencies include the age of the DT fill (a proxy for the He3 accumulation), the apparent ion-temperature asymmetries (a proxy for the L = 1 mode from target offset and laser mispointing), the ratio of the laser-beam radius to the target radius (a proxy for mid-modes from the laser illumination pattern), and hydro-stability parameters such as adiabat and in-flight aspect ratio, which govern the stability to short wavelength modes from laser imprinting and surface roughness. A similar statistical analysis has been carried out for the ion temperature and areal density. It is shown that all the measured stagnation properties exhibit dependencies on parameters similar to those used to predict the fusion yield. Having different measured properties leading to similar dependencies further validates the statistical analysis and provides a more-accurate tool for designing higher-performance implosions. [1] V. Gopalaswamy et al., Nature 565, 581 (2019).
[2] A. Lees et al., Phys. Rev. Lett. 127, 105001 (2021).
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Monday, October 17, 2022 2:48PM - 3:00PM |
CO04.00005: A Simulation-Driven Approach to Infer Hot-Spot Conditions in Inertial Confinement Fusion Implosions Ka Ming Woo, Riccardo Betti, Cliff A Thomas, Christian Stoeckl, Kristen Churnetski, Chad J Forrest, Rahul C Shah, Duc Cao, Timothy J Collins, Varchas Gopalaswamy, James P Knauer, Wolfgang R Theobald A 3-D reconstruction of the hot spot of inertial fusion implosion is carried out using a new simulation-driven approach that enables a more-complete inference of hot-spot conditions including the effect of quasi-isotropic flows on apparent ion temperatures. This simulation-driven reconstruction provides a way to determine the consistency of areal density (rR) measurements when the shell mass uniformity is significantly degraded by low modes. This technique uses a set of experimental signatures including neutron yields, apparent ion temperatures and areal densities measured at different lines of sight, as well as hot-spot shape information from x-ray images. All measurements are simultaneously reconstructed using the 3-D deceleration-phase simulation inertial confinement fusion code DEC3D. Both 1-D initial conditions at the onset of the deceleration phase and 3-D initial perturbations are optimized by the gradient descent algorithm. Reasonable agreements between reconstructed and measured observables including neutron yields and rR are obtained. This material is supported by the Department of Energy National Nuclear Security Administration under Award No. DE-NA0003856. |
Monday, October 17, 2022 3:00PM - 3:12PM |
CO04.00006: Increasing Performance of Direct-Drive Inertial Confinement Fusion Implosions via Enhanced Energy Coupling Varchas Gopalaswamy, Christian Stoeckl, Riccardo Betti, James P Knauer, Aarne Lees, Dhrumir P Patel, Connor A Williams, Rahman Ejaz, Pericles S Farmakis, Duc Cao, Cliff A Thomas, Jonathan Carroll-Nellenback, Suxing Hu, Timothy J Collins, Valeri N Goncharov, Vladimir Y Glebov, Zaarah L Mohamed, Chad J Forrest, Kristen Churnetski, Rahul C Shah, Steven T Ivancic, Michael J Rosenberg, Hans Rinderknecht, Sean P Regan, Dana H Edgell, Wolfgang R Theobald, Mark J Bonino, Roger T Janezic, Walter Shmyada, Siddharth Sampat, Owen M Mannion, Maria Gatu-Johnson
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Monday, October 17, 2022 3:12PM - 3:24PM |
CO04.00007: Hot-Electron–Preheat Mitigation Using Silicon-Doped Layer Shells on OMEGA Kristen Churnetski, Dhrumir Patel, Wolfgang R Theobald, Riccardo Betti, Michael J Rosenberg, Andrey Solodov, Christian Stoeckl, Sean P Regan, Justin H Kunimune, Johan A Frenje The impact of Si-doped CH layer shells on the mitigation of hot-electron preheat has been studied on OMEGA. An implosion experiment with 60-beam symmetric illumination was conducted with the small-spot SG5-650 distributed phase plates and 900-μm-outer-diam targets to increase hot-electron production [W. Theobald et al., Phys Plasmas 29, 012705 (2022)]. This experiment used D2 gas filled targets with 6% Si-doped CH layer shells with a pure CH inner layer and mass-equivalent pure-CH shells for comparison. Implosions with the Si-doped layer shells produced more neutrons, lower hard x-ray (HXR) signals, and achieved higher areal densities than the pure-CH shell implosions. The hot-electron temperature, Thot, and total hot-electron energy, Ehot, was inferred from the signal of an absolutely calibrated HXR detector. The Si‑doped layer capsules had lower inferred Thot and Ehot than the pure-CH shell counterparts by factors of 1.1 and 1.8, respectively, indicating the mitigation of preheat. A follow-up campaign with fully Si-doped CH shells is scheduled to understand the individual contributions to the HXR signal from the corona and payload. |
Monday, October 17, 2022 3:24PM - 3:36PM |
CO04.00008: Proof-of-Principle Experiment on the Dynamic Shell Formation Concept on the OMEGA Laser Igor Igumenshchev, Wolfgang R Theobald, Mark J Bonino, Edward M Campbell, Timothy J Collins, Sarah Fess, Valeri N Goncharov, David R Harding, Nathaniel R Shaffer, William T Trickey, Siddharth Sampat, Rahul C Shah, Alexander Shvydky, Christian Stoeckl, Leon Waxer, Arnaud Colaitis, Romain Loitard, Stefano Atzeni, Francesco Barbato, Lorenzo Savino, Noel Alfonso, Alex Haid A dynamic shell implosion concept in direct-drive inertial confinement fusion utilizes |
Monday, October 17, 2022 3:36PM - 3:48PM |
CO04.00009: Using Scattered-Light Data to Validate 2-D Radiation-Hydrodynamic Energy-Coupling Models in Polar-Direct-Drive Implosions at the National Ignition Facility Steven Kostick, Michael J Rosenberg, P. B Radha, John A Marozas, Stephen Craxton, Anirudh Sharma, Joe Katz, T. Filkins, Wolfgang R Theobald, Timothy J Collins, Sean P Regan, Nuno Lemos, Eleanor Tubman, James S Ross, Neil Butler, George F Swadling, Ricky Sommers, Joel Stanley, John D Moody Data from the scattered-light time-history diagnostic (SLTD)[1] and the full-aperture backscatter stations (FABS) at the National Ignition Facility (NIF) have been analyzed and used to evaluate 2-D radiation-hydrodynamic energy-coupling models in polar-direct-drive (PDD)[2] inertial confinement fusion experiments. The SLTD array consists of 11 (eventually 15) units mounted at a variety of polar and azimuthal angles in the NIF target chamber. The FABS array consists of eight units mounted in the southern hemisphere in two quads. Both FABS and SLTD units measure time-resolved scattered light in different wavelength bands: stimulated Brillouin scattering (SBS) (350 to 352 nm) and stimulated Raman scattering (400 to 750 nm). The SBS data have been compared with predictions from the hydrodynamics codes SAGE and DRACO for PDD experiments including CH shell implosions and solid spheres. DRACO includes the effects of cross-beam energy transfer. The evaluation of time-resolved and angular-resolved SBS data will be discussed. |
Monday, October 17, 2022 3:48PM - 4:00PM |
CO04.00010: SAGE Hydrodynamic Simulations of Scattered Light from Direct-Drive Implosions of Large-Diameter Targets at the National Ignition Facility Stephen Craxton, Steven Kostick, Michael J Rosenberg, Anirudh Sharma, Emma M Garcia, P. B Radha, John A Marozas, T. Filkins, Wolfgang R Theobald, Joseph D Katz, Timothy J Collins, Sean P Regan, Nuno Lemos, Eleanor Tubman, James S Ross, Neil Butler, George F Swadling, Ricky Sommers, Joel Stanley, John D Moody, Charles B Yeamans The 2-D hydrodynamics code SAGE, which includes 3-D ray tracing, has been used to model scattered light from polar-direct-drive implosions at the National Ignition Facility. Predictions have been compared with the full-aperture backscatter station (FABS) diagnostic and the scattered-light time-history diagnostic (SLTD).[1],[2] For a shot with a picket pulse, the three-peaked predicted scattered-light time history agrees closely in an absolute comparison with the FABS (Q36B) at 50° from the south pole; analysis of the simulations shows which laser beams contribute unabsorbed light to the detector at different times. Predictions of the angular dependence are generally consistent with the SLTD diagnostics. For a 4-mm CH low-convergence implosion (N190227-001),[3] FABS measurements are consistent with the predicted absorption of ~95%. Ongoing improvements to the absolute calibration will allow these detectors to more tightly constrain hydrodynamic modeling. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0003856. [1] M. J. Rosenberg et al., Rev. Sci. Instrum. 92, 033511 (2021).
[2] S. Kostick et al., this meeting.
[3] C. B. Yeamans et al., Nucl. Fusion 61, 046031 (2021).
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Monday, October 17, 2022 4:00PM - 4:12PM |
CO04.00011: Measuring the rarefaction wave dynamics from shock release in spherical geometry Aarne Lees, Daniel H Barnak, Riccardo Betti, Varchas Gopalaswamy, Alexander Shvydky, Zaire Sprowal In inertial confinement fusion (ICF) implosions, the hot-spot pressure, the convergence ratio, and the areal density at stagnation are inversely proportional to the hot-spot pressure at the beginning of the deceleration phase. The hot-spot pressure at the onset of deceleration is set by the stagnation of material in the rarefaction wave from the shock release when its kinetic energy is converted into internal energy. Accurate modeling of the shock release is therefore crucial to understanding ICF performance. Shock release experiments were carried out in spherical geometry on the OMEGA laser using a cone-in-shell setup. A shock, driven by a short picket pulse, breaks out of the shell and releases material from the shell's inner surface. The converging release material collides with a solid fused-silica hemisphere witness at the center of the target at which time the kinetic energy of the release material is converted into internal energy, launching a shock into the witness. VISAR measurements of the release-driven shock in the witness were obtained for varying laser-drive intensities. The measurements are used to validate modeling of the rarefaction wave dynamics in radiation-hydrodynamic simulations. |
Monday, October 17, 2022 4:12PM - 4:24PM |
CO04.00012: Impact of mid-Z gas fill on dynamics and performance of shock-driven implosions at the OMEGA laser Maria Gatu Johnson, Patrick J Adrian, Justin H Kunimune, Chikang Li, Richard D Petrasso, Fredrick H Seguin, Graeme D Sutcliffe, Johan A Frenje, Chad J Forrest, Vladimir Y Glebov, Neel V Kabadi, Christian Stoeckl, Hong W Sio, Lauren Green, Brian M Haines, Brett Keenan, William T Taitano, Brian D Appelbe, Aidan C Crilly, Grigory Kagan Shock-driven implosions with 100% D2 gas-fill compared to implosions with 50:50 N2D2 gas-fill have been performed at the OMEGA laser facility to test the impact of the added mid-Z fill gas on implosion dynamics and performance. Ion temperature (Tion) as inferred from the width of measured DD-neutron spectra from experiments with 7um-thick (8-um thick) CH shells is seen to be 34±6% (8±2%) higher for the N2D2 implosions than for the D2-only case, while the DD-neutron yield from the D2-only implosion is 7.2±0.5 (5.5±0.3) times higher than from the N2D2 gas-fill. In this talk, the implications of these results in terms of shock heating scaling with mass, interspecies equilibration rates, radiative loss, and diffusive shell mixing are discussed. The Tion enhancement is found to result from more efficient shock coupling to N than to D, heat transfer from N to D on the time scale of the implosion, and insufficient ion-electron equilibration for radiative loss to propagate to the ions before burn. The yield difference results from a lower fraction of the D content being hot enough to burn in the N2D2-fill than in the D2-only fill implosions. |
Monday, October 17, 2022 4:24PM - 4:36PM |
CO04.00013: Hydrodynamic scaling and hot electron preheat in NIF and OMEGA direct-drive ICF implosions Michael J Rosenberg, Andrey Solodov, Alison R Christopherson, Riccardo Betti, Radha Bahukutumbi, Christian Stoeckl, Matthias Hohenberger, Benjamin Bachmann, Pierre A Michel, Gareth N Hall, Steven Kostick, Chad J Forrest, Vladimir Y Glebov, Frederic J Marshall, Christine M Krauland, Timothy J Collins, Valeri N Goncharov, Wolfgang R Theobald, Sean P Regan Hydrodynamic scaling of direct-drive ICF implosion properties and hot electron preheat, which may degrade compression, have been studied at different scales in polar direct drive (PDD) experiments on the National Ignition Facility (NIF) and OMEGA. Hard x-ray emission from buried Ge-doped layers was measured in NIF implosions of 2.3 mm CH shells at 730 kJ laser energy to infer ~0.2% of laser energy deposited as hot-electron preheat in the inner ~80% of the unablated shell at an intensity of 1015 W/cm2, close to the tolerable level of preheat in direct-drive ignition designs. Hydrodynamically equivalent implosions on OMEGA at 3.4 times smaller scale (40 times less laser energy) show similar levels of preheat and implosion trajectories that approximately follow the expected hydrodynamic scaling. These results support the hydrodynamic scaling of warm target implosions between OMEGA and NIF scales. To aid extrapolation of these results to direct-drive ignition designs, additional experiments were conducted on NIF at the 3-mm, 1.5-MJ scale. Hot electron preheat and implosion energetics from these ignition-scale experiments will be discussed. |
Monday, October 17, 2022 4:36PM - 4:48PM |
CO04.00014: Physics Requirements for High-Gain Inertial Fusion Target Designs Valeri N Goncharov, William T Trickey, Igor Igumenshchev, Timothy J Collins, Nathaniel R Shaffer, Alexander Shvydky, Dustin Froula, Sean P Regan, Yousef Lawrence Recent progress in target performance of laser-direct-drive inertial confinement fusion (ICF) implosions has renewed interest in high-gain (G ~ 100) ICF target designs for various applications, including the Stockpile Stewardship Program and energy production. There are substantial differences in design parameter space between current best-performance implosions and high-gain designs; if the current implosions maximize hydroefficiency and energy coupled to the hot spot, designs with high yield will require increased mass and shell convergence and improved shell confinement. Increasing drive pressure by a factor of 2 to 3 from current laser-direct-drive implosions, which is achievable by mitigating coupling losses caused by laser–plasma interactions, offers the highest leverage in achieving the high-yield goals. This talk will review the implosion physics of high-gain designs that must be experimentally validated and discuss physics gaps that need to be addressed. |
Monday, October 17, 2022 4:48PM - 5:00PM |
CO04.00015: Omega-Next Laser Facility Target Design-Space Proposal John A Marozas, Timothy J Collins, Patrick m McKenty, Duc Cao, William T Trickey, Valeri N Goncharov, Jon D Zuegel, Christophe Dorrer The University of Rochester plans a next-generation inertial confinement fusion (ICF) facility capable of direct- or indirect-drive modes. The OMEGA Next Laser Facility intends to operate upward in energy to access ICF conditions unreachable by OMEGA, allowing it to explore design spaces including alpha burn (marginal ignition), high areal density, and, potentially, ignition using modern upgrades in laser technology that promise reductions in deleterious laser–plasma instabilities that limit current ICF laser systems. The upgraded laser system includes clustered beams utilized for multiple combinations such as differing spot shapes, pulse epochs, and wavelengths, all together with broadband dispersed light. The laser-beam clusters spread over 4 illuminate the target with pulse shaping, uniformity, and energy necessary to achieve a burning plasma upward to ignition while fielding a variety of target dimensions and compositions. This talk explores the expansive design space for the OMEGA Next Laser Facility, providing a wide range of target design options leveraging new ICF laser system advances. |
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