SPRG Seminars
January 29, 2013:
"Magnetic helicity fluxes and dynamo saturation"
Gustavo Guerrero, Solar Physics, HEPL, Stanford University
Many astrophysical bodies harbor magnetic fields that are thought to be sustained by a dynamo process. However, it has been argued that the production of large-scale magnetic fields by mean-field dynamo action is strongly suppressed at large magnetic Reynolds numbers owing to the conservation of magnetic helicity. This phenomenon is known as catastrophic quenching. In this seminar I discuss the role of magnetic helicity in the dynamo mechanism and its importance in the generation of large-scale magnetic field. I quickly review the catastrophic quenching problem and the way how it could be alleviated when the system is able to get rid of small scale magnetic helicity. I will present recent high resolution 3D dynamo simulations where advective fluxes releases magnetic helicity away from the domain allowing dynamo action even for high magnetic Reynolds numbers.