Eigenmode analysis of compressional poloidal modes in a self‐consistent magnetic field
Abstract
In this study, we simulate a self‐consistent magnetic field that satisfies force balance with a model ring current that is radially localized, axisymmetric, and has anisotropic plasma pressure. We find that the magnetic field dip forms near the high plasma pressure region with plasma β >∼ 0.6, and the formed magnetic dip becomes deeper for larger plasma β and also slightly deeper for larger anisotropy. We perform linear analysis on a ppol of self‐consistent equilibria for second harmonic compressional poloidal modes of sufficiently high azimuthal wave number. We investigate the effect of anisotropic pressure on the eigenfrequency of the poloidal modes and the characteristics of the compressional magnetic field component. We find that the eigenfrequency is reduced at the outer edge of the thermal pressure peak and increased at the inner edge. The compressional magnetic field component occurs primarily within 10° of the equator on both the inner and outer edges, with stronger compressional magnetic field component on the outer edge. Larger β and smaller anisotropy can increase the change of eigenfrequency and the strength of the compressional magnetic field component. The critical condition on plasma β and pressure anisotropy of an Alfvén ballooning instability is also identified.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Oct 01, 2017
- Source ID
- 10.1002/2017ja024376
Entities
People
- A. A. Chan
- Liheng Zheng
- Lunjin Chen
- Zhiyang Xia
Organizations
- Air Force Office of Scientific Research
- National Aeronautics and Space Administration
- Rice University
- University of Texas at Dallas