Back reaction to the spectrum of magnetic field in the kinetic dynamo theory - Modified Kulsrud-Anderson equation

We take account of the lowest order back reaction on a fluid and modify the Kulsrud-Anderson equation, partial derivative(t)epsilon(M) = 2(gamma)epsil on(M), obtained in the kinetic dynamo theory, where epsilon(M) is the energ y density of the magnetic field. We apply our results to certain astrophysi cal stages where the magnetic field is expected to be amplified by the dyna mo mechanism.