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Autores principales: Rosen, Maxwell H., Sengupta, Wrick, Ochs, Ian, Diaz, Felix Parra, Hammett, Gregory W.
Formato: Preprint
Publicado: 2024
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Acceso en línea:https://arxiv.org/abs/2411.14294
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author Rosen, Maxwell H.
Sengupta, Wrick
Ochs, Ian
Diaz, Felix Parra
Hammett, Gregory W.
author_facet Rosen, Maxwell H.
Sengupta, Wrick
Ochs, Ian
Diaz, Felix Parra
Hammett, Gregory W.
contents Collisions are crucial in governing particle and energy transport in plasmas confined in a magnetic mirror trap. Modern gyrokinetic codes model transport in magnetic mirrors, but some utilize approximate model collision operators. This study focuses on a Pastukhov-style method of images calculation of particle and energy confinement times using a Lenard-Bernstein model collision operator. Prior work on parallel particle and energy balances used a different Fokker-Planck plasma collision operator. The method must be extended in non-trivial ways to study the Lenard-Bernstein operator. To assess the effectiveness of our approach, we compare our results with a modern finite element solver. Our findings reveal that the particle confinement time scales like $a \exp(a^2)$ using the Lenard-Bernstein operator, in contrast to the more accurate scaling that the Coulomb collision operator would yield $a^2 \exp(a^2)$, where $a^2$ is approximately proportional to the ambipolar potential. We propose that codes solving for collisional losses in magnetic mirrors utilizing the Lenard-Bernstein or Dougherty collision operator scale their collision frequency of any electrostatically confined species. This study illuminates the collision operator's intricate role in the Pastukhov-style method of images calculation of collisional confinement.
format Preprint
id arxiv_https___arxiv_org_abs_2411_14294
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Enhanced Collisional Losses from a Magnetic Mirror Using the Lenard-Bernstein Collision Operator
Rosen, Maxwell H.
Sengupta, Wrick
Ochs, Ian
Diaz, Felix Parra
Hammett, Gregory W.
Plasma Physics
Collisions are crucial in governing particle and energy transport in plasmas confined in a magnetic mirror trap. Modern gyrokinetic codes model transport in magnetic mirrors, but some utilize approximate model collision operators. This study focuses on a Pastukhov-style method of images calculation of particle and energy confinement times using a Lenard-Bernstein model collision operator. Prior work on parallel particle and energy balances used a different Fokker-Planck plasma collision operator. The method must be extended in non-trivial ways to study the Lenard-Bernstein operator. To assess the effectiveness of our approach, we compare our results with a modern finite element solver. Our findings reveal that the particle confinement time scales like $a \exp(a^2)$ using the Lenard-Bernstein operator, in contrast to the more accurate scaling that the Coulomb collision operator would yield $a^2 \exp(a^2)$, where $a^2$ is approximately proportional to the ambipolar potential. We propose that codes solving for collisional losses in magnetic mirrors utilizing the Lenard-Bernstein or Dougherty collision operator scale their collision frequency of any electrostatically confined species. This study illuminates the collision operator's intricate role in the Pastukhov-style method of images calculation of collisional confinement.
title Enhanced Collisional Losses from a Magnetic Mirror Using the Lenard-Bernstein Collision Operator
topic Plasma Physics
url https://arxiv.org/abs/2411.14294