DR cross section, shown in the inset, is dominated by two features. The first is the $n\rightarrow \infty$ accumulation of resonances at the $\epsilon=8$ eV series limit — those which can be treated in the usual high-$T$ fashion [@burgess; @burgsum] and are therefore susceptible to suppression according to our formulation above. However, there is a second strong contribution from the lowest accessible resonances just above the threshold electron energy, which, according to the Rydberg consideration $3^2/n^2\approx \epsilon_3=0.6$ Ryd, occur here for $n=4$. More generally, these low-lying states are typical of the low-lying DR spectrum [@nussbaumer][^2]. The $1s^22p4l$ resonances decay predominantly to the $1s^22s2p$, $1s^22p^2$ and $1s^22s4l$ states. These states lie well below the ionization limit and so are not susceptible to further reionization. Since there should be no density suppression then, we seek a modified suppression factor which tends toward unity (i.e., no suppression) at lower temperatures.

![\[fig4\] DR of . The inset shows the (zero-density) DR cross section convoluted with a 0.1 eV FWHM Gaussian. The spectrum is dominated by two features: the $n=4$ DR resonance manifold below 1.0 eV and the $n\rightarrow\infty$ Rydberg resonances accumulating at the $2s\rightarrow 2p$ series limit $\epsilon_{3}(q_0)\approx 8$ eV. The main figure shows 