Residual currents detected with a correcting electrode in a modified Bayard–Alpert hot-cathode-ionization gauge

A nude-type hot-cathode-ionization-gauge head with correcting electrode and shield tube, succeeded in reducing practical pressure-measurement errors caused by an influx of photoelectrons in a synchrotron radiation environment. In the development of this modified Bayard–Alpert hot-cathode-ionization gauge, experimental results showed that a basic ion current generated around the correcting electrode by emission from the gauge filament, was proportional to an emission current (less than 10% of the normal emission current) detected with a grid of correcting electrode, and that differences between estimated and measured basic ion currents in a pressure range of higher than 10−8Pa order meant pressure-independent residual currents detected with the correcting electrode. By using calculated forward x-ray currents, these results also showed that the estimated residual currents with the correcting electrode were mainly caused by x rays from the grid of the hot-cathode-ionization-gauge head and the grid of correct...