Speaker
Fabio Del Sordo
(NORDITA)
Description
Estimates for the nonlinear alpha effect in helical
turbulence are
presented using two different approaches where a uniform
magnetic
field is applied either to the actual field, or where separate
evolution equations are solved for a set of different test
fields.
Both approaches agree for stronger fields, but there are
apparent
discrepancies for weaker fields that can be explained by the
influence
of dynamo-generated meso-scale magnetic fields.
Examples are discussed where with an imposed magnetic field
the alpha
effect is either drastically overestimated, or drastically
underestimated
compared with the kinematic value.
It is demonstrated that the kinematic value can be estimated
correctly by
reseting the magnetic field in regular time intervals.
Primary author
Alexander Hubbard
(Nordita)
Co-authors
Axel Brandenburg
(Nordita)
Fabio Del Sordo
(NORDITA)
Dr
Petri Käpylä
(University of Helsinki)
