Bulletin of the American Physical Society
63rd Annual Meeting of the APS Division of Plasma Physics
Volume 66, Number 13
Monday–Friday, November 8–12, 2021; Pittsburgh, PA
Session QI02: HED/ICF/MFE: Thermonuclear BurnInvited Live
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Chair: Uri Shumlak, University of Washington Room: Ballroom C |
Wednesday, November 10, 2021 3:00PM - 3:30PM |
QI02.00001: Generating burning plasmas with improved implosions in the Hybrid-E platform Invited Speaker: Alex B Zylstra Improving the performance of implosions on NIF by increasing the energy coupled to the capsule has been a strategy pursued in the last several years. The main challenge in improving the energy coupling is in increasing the hohlraum efficiency while maintaining both control over the radiation drive symmetry and key implosion parameters, such as the implosion velocity and coast time. Improved hohlraum efficiency with symmetry control was recently demonstrated in the ‘Hybrid E’ platform[1], which introduces a small amount of wavelength detuning (Dl) to alter the amount of cross-beam energy transfer and increase drive on the hohlraum waist. Recent work has increased the velocity and increased the late-time ablation pressure as the capsule implodes, both of which lead to large increases in stagnation pressure and implosion performance, with the yield tripling from earlier results. These implosions have now entered the burning plasma regime[2-4], with Qa ~ 1.5. A detailed comparison of the increased stagnation pressure with these key design parameters, and expected scaling relations, will be discussed to guide the path forward towards even higher implosion performance. |
Wednesday, November 10, 2021 3:30PM - 4:00PM |
QI02.00002: Achieving a Social License for Fusion Energy Invited Speaker: Seth Hoedl Fusion has the potential to address humanity’s energy needs. However, there is a risk that fusion will not play a substantial role in mitigating climate change or alleviating energy poverty due to a lack of social acceptance. This risk is not academic -- other promising technologies, such as fission reactors, spent fuel waste repositories (i.e., Yucca Mountain), genetically modified foods, and even vaccines, struggle because they are rejected by a substantial fraction of society. Conventional approaches to social acceptance, including risk-reducing technical solutions, such as replacing fission with fusion, and better “communication” or “education,” are unlikely, on their own, to alleviate a lack of acceptance [1]. |
Wednesday, November 10, 2021 4:00PM - 4:30PM |
QI02.00003: Marble Experiments on the National Ignition Facility: One- and Two-Shock Implosions for Studying the Effect of Heterogeneous Mix on Thermonuclear Burn Invited Speaker: Brian J Albright The performance of inertial confinement fusion implosions can be affected by mix through many different mechanisms, including the dilution of the fusion fuel by ablator material. The magnitude of the effect is dependent not only on the amount of mix, but also on the morphology, that is, the heterogeneity of the mix. Los Alamos National Laboratory has developed a model [1] that describes the effect of heterogeneous mix on thermonuclear burn. The Marble [2] campaign on NIF was developed to test this model. MARBLE utilizes capsules filled with deuterated plastic foam and a gas mixture that includes tritium. The foam is structured with voids, termed “macropores,” to control the degree of heterogeneity of the mix of foam and gas at burn time, and greater heterogeneity is expected to result in decreased DT neutron yield. The ratio of DT to DD neutron yield can be compared with simulations using the burn model. Initial experiments [3] utilizing an HT gas mixture failed to demonstrate the expected decrease in yield ratio with increased macropore diameter [3]. Detailed simulations [4] of similar OMEGA experiments have shown that ion temperature differences between gas and foam can persist until burn time, resulting in temperature correlations with species concentration, an effect not included in the burn model. Recent experiments with an argon/tritium gas mixture have shown a reduction in the ion temperature variation and have demonstrated a yield ratio that is consistent with simulations. |
Wednesday, November 10, 2021 4:30PM - 5:00PM |
QI02.00004: Theoretical interpretation of the operational density limit and comparison to experimental data Invited Speaker: Maurizio Giacomin The operational density limit represents the maximum plasma density that can be achieved in magnetic fusion devices before the plasma develops a strong magnetohydrodynamic activity that leads to a disruption. Experimental observations have pointed out a strong link between the cooling of the plasma at the tokamak edge and the crossing of the density limit, suggesting the important role played by edge physics on setting the maximum achievable density. In fact, the crossing of the density limit is usually preceded by a strong and localized radiation in the tokamak edge, denoted as MARFE. |
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