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Author: Wendell Horton
Requested Type: Poster
Submitted: 2018-03-08 08:44:56

Co-authors: D. Gogichaishvili, G. Mamatsashvili, G. Chagelishvili

Contact Info:
University of Texas at Austin
RLM 11.22 Speedway
Austin, Texas   78712
United States

Abstract Text:
Sheared flow driven magnetohydrodynamic turbulence produces cross-field momentum transport in MHD stable plasmas. We analyze the astrophysics Magneto-Rotational subcritical turbulence dynamics in both x and k-space to gain a deeper insight into the self-sustaining mechanism in linearly stable plasmas. As known from Chandrashkar in the presence of a background vertical or toroidal magnetic field, the linear growth has a transient character. We show that in the nonlinear regime this subcritical turbulence reaches a bursty steady of subcritical turbulence driven by the shear flow1. Anisotropic nonlinear structures in x and k-space2 appear from the transverse/angular redistribution of turbulent energy through the Reynolds and Maxwell stress tensors. In laboratory plasmas the same type of subcritical transverse turbulent cascade is observed in the LAPD, the Helimak and mirror machine from the applied Er(r,t) fields. The turbulence is sustained an interplay of the linear transient growth of modes and the nonlinear transverse cascade. The interplay of linear and nonlinear processes gives the “bypass concept” of subcritical turbulence measured in hydrodynamic experiments. In the linear transient growth of the MRI - the radial sheared flow is the energy/power source maintain the turbulence as with new 3D simulations. The turbulent scale lengths grow to the system size consistent the laboratory experiments in LAPD and the Helimak.
1. Mamatshvili, G. R., Gogichaishvili, D.Z.,Chagelishvili, G.D. and W. Horton, PhysRev E, 89, 043101, 2014.
2. Gogichaishvili, D. Z., Mamatshvili, G. R., Horton, W., Chagelishvili,D, Bodo G, ApJ, 845, 043101, 2017.