Characterization of Paschen curve anomolies at high P*D values

Paschen´s law is often used to estimate the breakdown voltage of high pressure gas switches commonly used in high voltage pulsed power systems based on the product of pressure and distance (pd) in a given gas. Paschen´s law predicts breakdown voltages for high pd values that scale approximately linearly with pd. However, it is clear from published literature and ARC Technology´s experimental data that the breakdown voltage deviates significantly from the theoretical Paschen curve at relatively high pd product values. It is also clear that these results are not consistent for different gap spacings and pressures with the same pd product. Therefore, initial tests have been performed to characterize this region of the paschen curve for N2, H2, and SF6 for pressures between 96.5 and 6900kPa and gap spacings of 0.508, 1.27 and 2.54 mm.