Author: Wendell Horton
Requested Type: Poster
Submitted: 2018-02-12 10:31:13
Co-authors: P. J. Morrison
University of Texas at Austin
1 University STA #C1500
Austin, Texas 78712-0
High pressure plasmas with reversed magnetic fields and nonuniform rotational flows are ubiquitous in nature and are produced in Field-Reversed Confinement [FRC] laboratory plasmas Ref.1. A large toroidal plasma current driven by neutral beam injection and external magnetic field driven by poloidal field coils produce the confinement geometry. The Grad-Shafranov equilibria Ref 2,3 are cylindrically magnetic field from external field coils and the toroidal plasma current. We investigate the ion and electron orbits in the geometry of the Norman F-R C with 12 external coils and the plasma current. Ions are launched from 8 NBI injectors at 35 KeV for 100msec producing a Ti ~2-3keV and Te ~ 100-200eV plasma. There is sheared EXB flow across the last closed magnetic field lines. The ion orbits become chaotic in the mirroring region curved where radius of curvature is comparable to ion gyroradius. There are ion orbits called the “butterfly pitch angle” distributions measured in the magnetosphere and chaotic orbits Ref 4. These orbits effect the drift waves and the Alfven wave stabilization. Analytic theory and 3D computer simulations are used to study the results on the plasma confinement. A strong radial electric field Er(r,t) develops ExB sheared rotation suppressing the core turbulence. Turbulence in the scrape off layer is modified by the nonlinear transverse cascade Ref.. The p~ B2/2 plasma is in a relaxed self-organized state. The turbulence is compared with the density fluctuations measured from X and O wave RF wave field scattering data .
1 L. Schmitz, et al. Suppressed ion-scale turbulence in a hot high-beta plasma, Nature Communication, 2016 [7:13860 | DOI: 10.1038/ncomms13860]
2 C. Copenhaver, Axisymmetric toroidal equilibrium with plasma flow,Phys Fluids 1983.
3 A. J. Cerfon and P. Freidberg, Phys Plasmas 17, 032502, 2010.
4 P. Shustov, A. Artemyev, E. Yushkov, Chaos 25, 1231118, 2015.
with abstracts on. FRC = Field-Reversed Configurations