Observations of neutral density in a modulated mercury positive column, using resonance absorption of the 2537 $Aring$ mercury line

Abstract

The neutral density in a mercury positive column, modulated at low frequencies, has been monitored using the 2537 Å absorption technique and the results compared with predictions and microwave measurements reported in an earlier paper. The agreement between the various results is presented as confirmatory evidence that low-frequency current modulation in positive columns is associated with perturbations in neutral density of the appropriate sense and magnitude to cause the clockwise hysteresis previously observed between electron density and discharge current.