  We show that, under Braginskii magneto-hydrodynamics, anti-parallel gradients
in average ion charge state and electron temperature can be unstable to the
growth of self-generated magnetic fields. The instability is analogous to the
field-generating thermomagnetic instability, although it is driven by the
collisional thermal force magnetic source term rather than the Biermann battery
term. The gradient in ion charge state causes a gradient in collisionality,
which couples with temperature perturbations to create a self-generated
magnetic field. This magnetic field deflects the electron heat flux in a way
that reinforces the temperature perturbation. The derived linearized growth
rate, typically on hydrodynamic timescales, includes the resistive and thermal
smoothing. It increases with large ion composition gradients and electron heat
flux, conditions typical of the hohlraum walls or contaminant mix jets in
inertial confinement fusion implosions. However, extended magneto-hydrodynamic
simulations indicate that the instability is usually dominated and stabilized
by the nonlinear Nernst advection, in a similar manner to the standard
thermomagnetic instability.
