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Numerical simulation of a relativistic magnetron using a fluid electron model

Physics of Plasmas

Roberds, Nicholas A.; Cartwright, Keith L.; Sandoval, Andrew J.; Beckwith, Kristian; Cyr, Eric C.; Bays, Nathan R.

An approach to numerically modeling relativistic magnetrons, in which the electrons are represented with a relativistic fluid, is described. A principal effect in the operation of a magnetron is space-charge-limited (SCL) emission of electrons from the cathode. We have developed an approximate SCL emission boundary condition for the fluid electron model. This boundary condition prescribes the flux of electrons as a function of the normal component of the electric field on the boundary. We show the results of a benchmarking activity that applies the fluid SCL boundary condition to the one-dimensional Child-Langmuir diode problem and a canonical two-dimensional diode problem. Simulation results for a two-dimensional A6 magnetron are then presented. Computed bunching of the electron cloud occurs and coincides with significant microwave power generation. Numerical convergence of the solution is considered. Sharp gradients in the solution quantities at the diocotron resonance, spanning an interval of three to four grid cells in the most well-resolved case, are present and likely affect convergence.

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TYPE Journal Article YEAR 2022
DOIOSTIScopus

Salt International Collaborations (FY22 Update)

Kuhlman, Kristopher L.; Matteo, Edward N.; Mills, Melissa M.; Jayne, Richard S.; Reedlunn, Benjamin; Sobolik, Steven; Bays, Nathan R.

This report summarizes the international collaborations conducted by Sandia funded by the US Department of Energy Office (DOE) of Nuclear Energy Spent Fuel and Waste Science & Technology (SFWST) as part of the Sandia National Laboratories Salt R&D and Salt International work packages. This report satisfies the level-three milestone M3SF-22SN010303063. Several stand-alone sections make up this summary report, each completed by the participants. The sections discuss international collaborations on geomechanical benchmarking exercises (WEIMOS), granular salt reconsolidation (KOMPASS), engineered barriers (RANGERS), numerical model comparison (DECOVALEX) and an NEA Salt Club working group on the development of scenarios as part of the performance assessment development process. Finally, we summarize events related to the US/German Workshop on Repository Research, Design and Operations. The work summarized in this annual update has occurred during the COVID-19 pandemic, and little international or domestic travel has occurred. Most of the collaborations have been conducted via email or as virtual meetings, but a slow return to travel and in-person meetings has begun.

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TYPE Other Report YEAR 2022
DOIOSTI

Electrostatic Relativistic Fluid Models of Electron Emission in a Warm Diode

IEEE International Conference on Plasma Science (ICOPS)

Hamlin, Nathaniel D.; Smith, Thomas M.; Roberds, Nicholas A.; Bays, Nathan R.; Beckwith, Kristian

A semi-analytic fluid model has been developed for characterizing relativistic electron emission across a warm diode gap. Here we demonstrate the use of this model in (i) verifying multi-fluid codes in modeling compressible relativistic electron flows (the EMPIRE-Fluid code is used as an example; see also Ref. 1), (ii) elucidating key physics mechanisms characterizing the influence of compressibility and relativistic injection speed of the electron flow, and (iii) characterizing the regimes over which a fluid model recovers physically reasonable solutions.

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TYPE Journal Article YEAR 2022
DOIOSTI
Results 476–500 of 2,510
Results 476–500 of 2,510
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