Events at Physics |
Events on Tuesday, December 16th, 2008
- Physics Department Colloquium
- Magnetic Self-Organization in the Reversed Field Pinch
- Time: 12:00 pm
- Place: 2241 Chamberlin Hall (coffee at 11:30 am)
- Speaker: John Sarff, Department of Physics, University of Wisconsin
- Abstract: Magnetic self-organization in a plasma refers to processes where, for example, gradients in the plasma current and pressure lead to magnetic instabilities, which in turn feedback on the structure of the plasma and its free energy sources. The reversed field pinch (RFP) magnetically confined plasma exhibits a number of self-organizing effects that resemble those observed or believed important in astrophysical plasmas, thus providing an excellent laboratory to help understand the self-organizing processes. The RFP is also a candidate approach to plasma confinement for thermonuclear fusion. In the fusion context, magnetic self-organization is both a challenge and opportunity for achieving a sustained hot plasma. Research from the Madison Symmetric Torus here in the UW physics department will be described to illustrate self-organization physics in the RFP.
- Astronomy Colloquium
- Dynamos and Magnetism in Rapidly Rotating Suns
- Time: 3:30 pm
- Place: 6515 Sterling Hall
- Speaker: Ben Brown, University of Colorado
- Abstract: When stars like our Sun are young, they rotate much faster than the Sun currently does. These rapidly rotating suns are observed to have strong magnetic fields, which likely arise from dynamo action in their turbulent convection zones. We explore stellar dynamos with 3-D simulations of turbulent convection in rotating spherical shells using the anelastic spherical harmonic (ASH) code. These simulated stars build strong magnetic fields in the bulk of their convection zone. This is in striking contrast to our understanding of the solar dynamo, where we think a tachocline of shear at the base of the convection zone is a crucial ingredient for the global-scale dynamo.
- Host: Professor Ellen