= Dynamo quenching
{title2=$\alpha(B)=\alpha_0/(1+B^2/B_*^2)$}
<Dynamo quenching> is the reduction or modification of magnetic-field generation by magnetic feedback on the generating flow and its correlations. The <Lorentz force> can change shear or turbulence, while <magnetic helicity> affects mean-field regeneration. A phenomenological <scalar> example is $\alpha(B)=\alpha_0/(1+B^2/B_*^2)$. In the illustrative amplitude equation $\dot B=[c\alpha(B)-d]B$ with $c,d>0$, a growing field saturates at $B^2=B_*^2(c\alpha_0/d-1)$ when $c\alpha_0>d$. This demonstrates the negative feedback mechanism without claiming that algebraic quenching is a complete solar closure.
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