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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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DOE OSTI2022

Parallel-Plate Avalanche Counter (PPAC) Fabrication for 240 Pu PFNS Measurement [Slides]

A LANL-LLNL joint program has been developed successfully to measure PFNS and established the most precisely determined $\chi$ matrices for 235,238 U and 239 Pu. It has been extended to 240 Pu now and possibly to 233 U in the future. An alternative method was developed to fabricate 240 Pu and a total of 12 targets were made with a total mass of 17.9 mg. The PFNS measurement for 240 Pu will begin in June, 2022 when the new beam cycle starts and the data analysis follows immediately afterward.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2022

Understanding the electromagnetic topology during the ohmic breakdown in tokamaks considering self-generated electric fields

We report that the physical mechanisms of the ohmic breakdown in a tokamak have been understood based on the classical Townsend avalanche theory. However, a new systematic theory (Yoo et al 2018 Nat. Commun.9 3523) recently demonstrated that electron avalanches during the ohmic breakdown are completely different from the Townsend avalanche due to strong self-generated electric fields. In this study, we elucidate the multi-dimensional effects of the self-generated electric field on plasma dynamics during the ohmic breakdown. We also propose a novel electromagnetic topology analysis method that can easily predict the overall plasma behavior and where the main plasma is generated. The topology analysis method is validated by a state-of-art particle simulation for various magnetic configurations. New physical insights into the complex electromagnetic topology would facilitate designing more reliable and optimized ohmic breakdown scenarios in future tokamaks, such as ITER and beyond.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗