FTP, name these systems which can self-excite magnetic fields.
In a mean-field treatment with isotropic turbulence, the evolution of this type of system is characterized by a pseudoscalar linearly related to the helicity spectrum. They are termed "fast" if the real part of the eigenfrequency does not decrease in the limit of zero resistivity. The pseudoscalar alpha is the namesake of an effect in these systems which can produce a poloidal field in the presence of a toroidal field. Galactic and stellar magnetic fields are thought to be produced by this type of system operating in rotating bodies of conducting fluid. FTP, name these systems which can self-excite magnetic fields.
In a mean-field treatment with isotropic turbulence, the evolution of this type of system is characterized by a pseudoscalar linearly related to the helicity spectrum.
{dynamo}