= Thermal-diffusion magnetic-field parameter
{title2=$Q_\kappa=B_0^2d^2/(\mu_0\rho\nu\kappa)=\zeta Q_{\mathrm{Ch}}$}
With <thermal diffusivity> $\kappa$ and <magnetic diffusivity> $\eta$, the standard <Chandrasekhar number> uses $\nu\eta$ in its denominator. A thermal-diffusion alternative uses $\nu\kappa$ and is $\zeta=\eta/\kappa$ times the standard parameter. In thermal-time <magnetoconvection> equations, the linear magnetic-force coefficient is $\sigma Q_\kappa=\sigma\zeta Q_{\mathrm{Ch}}$. Specifying the convention prevents a missing diffusivity factor in a dispersion relation.
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