Fig. 8

Peak values of γ/ω_p as a function of \( p_{{{\text{He}}^{ + } }} \) and \( p_{{{\text{O}}^{ + } }} \), using the same parameters as Fig. 7 except for the ion composition. Color scale indicates γ/ω_p. White and black dotted lines delineate \( p_{{{\text{H}}^{ + } }} \) from 50% to 95% at 5% intervals. Magenta dotted lines show M from 1.5 amu to 5.5 amu at 0.5 amu intervals. Yellow stars indicate the peak values of γ/ω_p for cases 1–3 (Fig. 7b, d, and f), while an orange star shows a value for the plasma trough that consists of H⁺ and He⁺ ions and has M = 1.5 amu