Is there something else involving pressure going on here too?
"Paschen measurements are taken which relate the minimum potential required to spark across a gap between two electrodes. The minimum potential is plotted versus the pressure-distance value for electrodes of a given geometry. For most gases, the potential decreases as the pressure decreases. For CO2, the minimum in the curve happens to be at Mars atmospheric pressures (5-7 mm Hg) for many distances and geometries. However, a very small amount (<0.1%) of mixing gases radically changes the curve, as noted by Leach. Here, !
we present the first experimental results of a Paschen curve for a Mars gas mixture compared with 100% pure CO2."
Thus the electrodes fixed at 0.1 cm apart provided the parallelplate geometry.
The chamber was pumped down to 104 mm Hg and backfilled to ~ 50 mm Hg with the atmospheric gas. It was pumped down again to remove residual gases and contaminants. The gases that were used are 100% CO2 and a Mars gas mixture provided by Praxair Inc. that consisted of 95.5% carbon dioxide, 2.7% nitrogen, 1.6% argon, 0.13% oxygen and 0.07% carbon monoxide.
Leach's Curves:
Pseudospark Switches:
