A NEW METHOD OF OPERATING AN OMEGATRON TO IMPROVE PERFORMANCE - TIME SEPARATION OF PROCESSES

The sensitivity of omegatron mass spectrometers is limited by the space-charge effects due to the electronic and ionic charges, although in usual conditions a partial compensation of these charges occurs. A new operation mode of the omegatron, characterized by the time separation of the ionization and ion collection processes, is proposed. Experimental data are reported which show that a considerable increase in sensitivity, together with a more stable mass calibration of the instrument, can be achieved in this operation mode, especially in low pressure measurements. The time separation mode may also prove to be a useful tool in the study of ion-molecule reactions.