  We directly optimize stellarator neoclassical ion transport while holding
neoclassical electron transport at a moderate level, creating a scenario
favorable for impurity expulsion and retaining good ion confinement.
Traditional neoclassical stellarator optimization has focused on minimizing
$\epsilon_\mathrm{eff}$, the geometric factor that characterizes the amount of
radial transport due to particles in the $1/\nu$ regime. Under expected
reactor-relevant conditions, core electrons will be in the $1/\nu$ regime and
core fuel ions will be in the $\sqrt{\nu}$ regime. Traditional optimizations
thus minimize electron transport and rely on the radial electric field
$\left(E_r\right)$ that develops to confine the ions. This often results in an
inward-pointing $E_r$ that drives high-$Z$ impurities into the core, which may
be troublesome in future reactors. In our optimizations, we increase the ratio
of the thermal transport coefficients $L_{1 1}^{e}/L_{1 1}^{i}$, which previous
work has shown can create an outward-pointing $E_r$. This effect is very
beneficial for impurity expulsion. We obtain self-consistent density,
temperature, and $E_r$ profiles at reactor-relevant conditions for optimized
equilibria. These equilibria are expected to enjoy significantly improved
impurity transport properties. We conclude by providing several directions of
future research that may help further improve the presented optimization
algorithm.
