Pressure/current characteristics of a magnetron cold cathode gauge

The gauge characteristics for a magnetron gauge in the pressure range 10−8-10−5 mbar with nitrogen as a test gas have been studied. The discharge current versus pressure was measured at different magnetic fields from 0.10 to 0.15 T and anode voltages from 4.0 to 7.0 kV. The results showed that a change of slope appeared at pressures between 5×10−8 and 5×10−7 mbar. At higher magnetic fields, a change of slope appeared at lower pressures. The slope of the curve below the inflection was higher than that above the inflection. At the lowest magnetic field (0.10 T), a divergence of the curves was observed at pressures below the inflection. The slope of the curve showed no clear dependence on applied voltage.