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We have extended our previous mean-field galactic dynamo model which includedalgebraic and dynamic alpha nonlinearities (Kleeorin et al., A&A, v. 387, 453,2002), to include also a quenching of turbulent diffusivity. We readily obtainequilibrium states for the large-scale magnetic field in the local disc dynamomodel, and these fields have strengths that are comparable to the equipartitionfield strength. We find that the algebraic nonlinearity alone (i.e. quenchingof both the alpha effect and turbulent magnetic diffusion) cannot saturate thegrowth of the mean magnetic field; only the combined effect of algebraic anddynamic nonlinearities can limit the growth of the mean magnetic field.However, in contrast to our earlier work without quenching of the turbulentdiffusivity, we cannot now find satisfactory solutions in the no-zapproximation to the axisymmetric galactic dynamo problem.Comment: 10 pages, 7 Postscript figures, aa.cls, Astron. Astroph., submitte

Nonlinear magnetic diffusion and magnetic helicity transport in galactic dynamos