"Nonlinear Convective Processes in Magnetized Temperature Filaments: Gyrokinetic Modeling and Experiments," by Richard Sydora (University of Alberta, Canada)

Date: 
Thursday, April 23, 2015 - 1:00pm to 2:00pm
Series: 
Plasma Seminars

Plasma Seminar

Physics and Astronomy Building (PAB) Room 4-330
Thursday, April 23, 2015
1-2 PM
Refreshments at 12:30 PM

Guest Speaker: Richard Sydora (University of Alberta, Canada)

Talk Title: "Nonlinear Convective Processes in Magnetized Temperature Filaments: Gyrokinetic Modeling and Experiments"

Abstract:

The subject of this presentation is motivated by past and recent experiments performed in the Large Plasma Device (LAPD) at UCLA where the evolution of a controlled, electron temperature filament embedded in the centre of a large magnetized plasma has been characterized. For example, the spatio-temporal pattern of the electrostatic potential, density, and magnetic fluctuations driven by thermal gradients have been followed in the linear and nonlinear regimes. Recent novel off-axis heat sources have allowed for more general shaping of the electron temperature profile that includes a hollow cylindrical filament embedded in a colder plasma giving a ring-shaped pattern in the cross-section, thus producing and an inner and outer thermal gradient. In order to investigate the nonlinear convection and transport in peaked and hollow filament temperature profiles 3D electromagnetic gyrokinetic particle simulations have been carried out using plasma conditions similar to the experiments. Above a certain temperature gradient threshold, drift-Alfven fluctuations were excited and induced a rapid thermal collapse on time scales consistent with experiment. This collapse process is part of a scenario involving transport avalanches that have been recently found in the experiment. The detailed physical processes along with comparison to experiments and next steps will be presented.

(In collaboration with B.V. Compernolle, J.E. Maggs, G.J. Morales, UCLA)

Event Attachments: 
Location: 
PAB 4-330