Pulsed time of flight mass spectrometers

Claim 1

A MASS-SPECTROMETER OPERATIVE IN A PULSE CYCLE AND COMPRISING, IN COMBINATION: A VACUUM-TIGHT ENVELOPE; A SET OF APERTURED ELECTRODES SPACED ALONG A COMMON LONGITUDINAL AXIS WITHIN SAID ENVELOPE; AN ION SOURCE FOR PROVIDING IONS AT ONE END OF SAID AXIS; MEANS FOR BIASING AT LEAST ONE ELECTRODE INTERMEDIATE BETWEEN THE ENDS OF THE ELECTRODE SET TO A GIVEN POTENTIAL FOR PROVIDING AN ION DRIFT REGION; PULSE GENERATOR MEANS CONNECTED TO A FIRST ELECTRODE AT SAID ONE END OF THE ELECTRODE SET FOR BIASING SAID FIRST ELECTRODE, AT LEAST DURING CERTAIN PORTIONS OF SAID CYCLE, TO A POTENTIAL WHICH IS MORE POSITIVE THAN THAT OF SAID INTERMEDIATE ELECTRODE FOR PREVENTING IONS FROM PASSING SAID FIRST ELECTRODE; PULSE GENERATOR MEANS CONNECTED TO A SECOND ELECTRODE AT THE OTHER END OF SAID ELECTRODE SET FROM SAID FIRST ELECTRODE FOR PERIODICALLY RAISING THE POTENTIAL OF SAID SECOND ELECTRODE TO A VALUE ABOVE SAID GIVEN POTENTIAL TO DEFLECT SELECTED IONS BACK ALONG THE LONGITUDINAL AXIS OF SAID SPECTROMETER; SAID PULSE GENERATOR MEANS BEING ARRANGED TO ALTERNATELY BIAS SAID FIRST ELECTRODE AND RAISE THE POTENTIAL OF SAID SECOND ELECTRODE AND MEANS FOR DETECTING THOSE SELECTED IONS SO DEFLECTED.