Self-similar solutions for resistive diffusion, Ohmic heating, and Ettingshausen effects in plasmas of arbitrary beta
File(s)POP21-AR-01868_accepted.pdf (453.62 KB)
Accepted version
Author(s)
Farrow, G
Chittenden, JP
Kagan, G
Type
Journal Article
Abstract
ABSTRACT
Magneto-inertial fusion (MIF) approaches, such as the MagLIF experiment, use magnetic fields in dense plasma to suppress cross-field thermal conduction, attempting to reduce heat loss and trap alpha particles to achieve ignition. However, the magnetic field can introduce other transport effects, some of which are deleterious. An understanding of these processes is thus crucial for accurate modeling of MIF. We generalize past work exploiting self-similar solutions to describe transport processes in planar geometry and compare the model to the radiation-magnetohydrodynamics (MHDs) code Chimera. We solve the 1D extended MHD equations under pressure balance, making no assumptions about the ratio of magnetic and thermal pressures in the plasma. The resulting ordinary differential equation (ODE) boundary value problem is solved using a shooting method, combining an implicit ODE solver and a Newton–Raphson root finder. We show that the Nernst effect dominates over resistive diffusion in high β plasma, but its significance is reduced as the β decreases. On the other hand, we find that Ettingshausen and Ohmic heating effects are dominant in low β plasma and can be observable in even order unity β plasma, though in the presence of a strong temperature gradient heat conduction remains dominant. We then present a test problem for the Ohmic heating and Ettingshausen effects which will be useful to validate codes modeling these effects. We also observe that the Ettingshausen effect plays a role in preventing temperature separation when Ohmic heating is strong. Neglecting this term may lead to overestimates for the electron temperature at a vacuum–plasma interface, such as at the edge of a z-pinch. The model developed can be used to provide test problems with arbitrary boundary conditions for magnetohydrodynamics codes with the ability to freely switch on terms to compare their individual implementations.
Magneto-inertial fusion (MIF) approaches, such as the MagLIF experiment, use magnetic fields in dense plasma to suppress cross-field thermal conduction, attempting to reduce heat loss and trap alpha particles to achieve ignition. However, the magnetic field can introduce other transport effects, some of which are deleterious. An understanding of these processes is thus crucial for accurate modeling of MIF. We generalize past work exploiting self-similar solutions to describe transport processes in planar geometry and compare the model to the radiation-magnetohydrodynamics (MHDs) code Chimera. We solve the 1D extended MHD equations under pressure balance, making no assumptions about the ratio of magnetic and thermal pressures in the plasma. The resulting ordinary differential equation (ODE) boundary value problem is solved using a shooting method, combining an implicit ODE solver and a Newton–Raphson root finder. We show that the Nernst effect dominates over resistive diffusion in high β plasma, but its significance is reduced as the β decreases. On the other hand, we find that Ettingshausen and Ohmic heating effects are dominant in low β plasma and can be observable in even order unity β plasma, though in the presence of a strong temperature gradient heat conduction remains dominant. We then present a test problem for the Ohmic heating and Ettingshausen effects which will be useful to validate codes modeling these effects. We also observe that the Ettingshausen effect plays a role in preventing temperature separation when Ohmic heating is strong. Neglecting this term may lead to overestimates for the electron temperature at a vacuum–plasma interface, such as at the edge of a z-pinch. The model developed can be used to provide test problems with arbitrary boundary conditions for magnetohydrodynamics codes with the ability to freely switch on terms to compare their individual implementations.
Date Issued
2022-03-01
Date Acceptance
2022-02-27
Citation
Physics of Plasmas, 2022, 29 (3)
ISSN
1070-664X
Publisher
American Institute of Physics
Journal / Book Title
Physics of Plasmas
Volume
29
Issue
3
Copyright Statement
© 2022 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
License URL
Sponsor
AWE Plc
Identifier
https://www.webofscience.com/api/gateway?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000779058500001&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=1ba7043ffcc86c417c072aa74d649202
Grant Number
30469588
Subjects
Science & Technology
Physical Sciences
Physics, Fluids & Plasmas
Physics
Z-PINCH
EQUILIBRIA
FUEL
Publication Status
Published
Article Number
ARTN 032703