BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Talks.cam//talks.cam.ac.uk//
X-WR-CALNAME:Talks.cam
BEGIN:VEVENT
SUMMARY:Dynamo action\, magnetorotational instability\, Alfvén waves: The
 ory and experiments on astrophysical magnetohydrodynamics - Frank Stefani 
 (Helmholtz-Zentrum Dresden)
DTSTART:20240205T140000Z
DTEND:20240205T150000Z
UID:TALK209035@talks.cam.ac.uk
CONTACT:Roger Dufresne
DESCRIPTION:The homogeneous dynamo effect in moving electrically conductin
 g fluids\, such as liquid metals or plasmas\, is responsible for magnetic-
 field generation in planets\, stars and galaxies. Magnetic fields\, in tur
 n\, can promote cosmic structure formation by destabilizing\, via the magn
 etorotational instability (MRI)\, rotational flows in accretion disks that
  otherwise would be hydrodynamically stable. \n\nFor a long time\, those t
 opics have been the subject of purely theoretical and numerical research. 
 This situation changed in 1999 when the threshold of magnetic-field self-e
 xcitation was crossed in two large-scale liquid-sodium experiments in Riga
  and Karlsruhe. Later\, the VKS dynamo experiment in Cadarache successfull
 y reproduced field reversals and excursions that are of great geophysical 
 interest. Various types of the MRI were studied in liquid metal experiment
 s at the Princeton Plasma Physics Laboratory and at Helmholtz-Zentrum Dres
 den-Rossendorf (HZDR). A liquid-rubidium experiment at the Dresden High Ma
 gnetic Field Laboratory (HLD) reached the “magic point” of coinciding 
 Alfvén and sound speeds\, which is thought to play a key role for the hea
 ting of the solar corona.\n\nAfter a short introduction to the basic equat
 ions of magnetohydrodynamics\, the lecture gives an overview about previou
 s and future liquid metal experiments on dynamo action\, Alfvén waves\, a
 nd magnetically triggered flow instabilities such as the MRI. Special focu
 s lies on a precession driven dynamo experiment that is presently being co
 nstructed in frame of the DRESDYN project at HZDR. Closely related to this
 \, some emphasis is placed on the potential role of various astronomical f
 orcings in triggering reversals of the geodynamo or even synchronizing the
  solar\ndynamo.
LOCATION:MR14 DAMTP and online
END:VEVENT
END:VCALENDAR