Nonlinear instability in simulations of Large Plasma Device turbulence
- Department of Physics and Astronomy, University of California, Los Angeles, California 90095-1547 (United States)
- Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)
Several simulations of turbulence in the Large Plasma Device (LAPD) [Gekelman et al., Rev. Sci. Instrum. 62, 2875 (1991)] are energetically analyzed and compared with each other and with the experiment. The simulations use the same model, but different axial boundary conditions. They employ either periodic, zero-value, zero-derivative, or sheath axial boundaries. The linear stability physics is different between the scenarios because the various boundary conditions allow the drift wave instability to access different axial structures, and the sheath boundary simulation contains a conducting wall mode instability which is just as unstable as the drift waves. Nevertheless, the turbulence in all the simulations is relatively similar because it is primarily driven by a robust nonlinear instability that is the same for all cases. The nonlinear instability preferentially drives k{sub ∥}=0 potential energy fluctuations, which then three-wave couple to k{sub ∥}≠0 potential energy fluctuations in order to access the adiabatic response to transfer their energy to kinetic energy fluctuations. The turbulence self-organizes to drive this nonlinear instability, which destroys the linear eigenmode structures, making the linear instabilities ineffective.
- OSTI ID:
- 22228063
- Journal Information:
- Physics of Plasmas, Vol. 20, Issue 5; Other Information: (c) 2013 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 1070-664X
- Country of Publication:
- United States
- Language:
- English
Similar Records
On generation of Alfvenic-like fluctuations by drift wave-zonal flow system in large plasma device experiments
Thermal plasma and fast ion transport in electrostatic turbulence in the large plasma device