Registration of currents of positive and negative ions in quadrupole mass spectrometer with one measuring channel

A modernized system for registration of the ion currents of MS7302 and MS7303 quadrupole mass spectrometers is described. Charge conversion in interaction of negative ions with a metal surface is used to measure their current, which allows the currents of both positive and negative ions to be measured with a single measuring channel and permits electrical switching from one registration mode to anther without loss of vacuum or stopping of the instrument.