Time-of-flight mass spectrometer with step-function-controlled field

Claim 1

A time-of-flight mass spectrometer wherein a mass spectrum of ions is obtained from a material under investigation by accelerating a group of the ions to velocities corresponding to their mass-to-charge ratios, making the group cover the distance to a target to allow the ions with different mass-to-charge ratios to separate and measuring the current of ions that reach the target, and displaying the course in time of the measured ion current; means for substantially continuously generating a beam of ions and accelerating such beam in the direction of a target area, a pair of deflection plates being disposed so that the ion beam passes between the plates; a source of voltage and means for varying the voltage as a stepfunction, said source being coupled to said deflection plates; a target slit and current detector disposed in the target area traversed by the ion beam so that for each such step function a group of the ions passing through said electrical field pass through said target slit and current detector; and means for recording the course in time of the current detector output signal.

Claim 9

A method of repeatedly obtaining a mass spectrum of ions from a material under investigation by accelerating a group of the ions to velocities corresponding to their mass-to-charge ratios, making this group cover the distance to a target to allow ions with different mass-to-charge ratios to become separated owing to the different magnitudes of their velocities, measuring the current of ions that have reached the target by means of an ion current detector and recording the course in the time of the measured ion current, improvement comprising; forming a series of the said ion groups by passing a beam of accelerated ions between two deflection electrodes and applying to these electrodes a deflection voltage which alternates between two levels chosen in such a way that the beam is deflected repeatedly towards, across and beyond the target and which describes, at least approximately, a step-function between the said levels in one or both directions of variation.

Claim 10

A method of repeatedly obtaining a mass spectrum of ions from a material under investigation by accelerating a group of the ions to velocities corresponding to their mass-to-charge ratios, making this group cover the distance to a target to allow ions with different mass-to-charge ratios to become separated owing to the different magnitudes of their velocities, measuring the current of ions that have reached the target by means of an ion current detector and recording the course in the time of the measured ion current, improvement comprising; forming a series of the said ion groups by passing a beam of accelerated ions between two deflection electrodes and applying to these electrodes a deflection voltage which alternates between two levels chosen in such a way that the beam is deflected repeatedly towards, across and beyond the target and which describes, at least approximately, a step-function between the said levels in one or both directions of variation.