MULTICHANNEL READOUT MASS SPECTROMETER

• US 3,641,340 A
• Filed: 09/22/1969
• Issued: 02/08/1972
• Est. Priority Date: 09/22/1969
• Status: Expired due to Term

• Current Assignee: George Jernakoff, Willem J. Van Der Grinten
• Original Assignee: George Jernakoff, Willem J. Van Der Grinten
• Inventors: Van Der Grinten, Willem J., Jernakoff, George
• Primary Examiner(s): Stolwein, Walter
• Assistant Examiner(s): Nelms, D. C.
• Application Number:
  US04/859,866
• Time in Patent Office: 869 Days
• Field of Search: 250/41.9R,41.9G,41.9D,41.9C,41.9TF,41.9DS,41.9AE
• US Class Current: 250/292
• CPC Class Codes: H01J 49/0027 Methods for using particle spectrometers
• CPC Class Codes: H01J 49/4215 Quadrupole mass filters H01J49/4225 takes precedence

Abstract

A multichannel readout mass spectrometer is described wherein the amplitude of the control voltage governing the passage of an ionized stream of a gas mixture through a quadrupole mass filter is employed to supervise the selection of readout channels individually recording various constituents of the ionized stream. For each readout channel, the control voltage is compared with a first preselected voltage to activate logic circuitry initiating recordation of a constituent of selected mass upon the readout channel and readout of the constituent is continued until a signal is generated from a second control voltage comparator circuit. Switching circuitry also is provided for recording the mass spectra of all constituents on a common channel simultaneously with a signal indicative of the recording interval for any one of the individual readout channels. The recording interval then is correlated with a single constituent forming the mass spectra whereupon readout of only the single constituent can be switched to the individual readout channel.

Claims

1. A multichannel readout mass spectrometer comprising means for ionizing a gaseous stream containing a plurality of constituents in unknown degrees of concentration, means for generating a control signal having an amplitude varying as a function of time, selection means responsive to the amplitude of said control signal for selectively passing ionized constituents of a given mass, means for measuring the quantity of ionized constituents passed by said selection means, a plurality of readout channels for recording the measured quantity of ionized constituents passed by said selection means, means for comparing the amplitude of said control signal with a signal of preselected amplitude, means responsive to said comparison means for directing the recording of said constituents to a first one of said readout channels, means for terminating recording of said constituents upon said first readout channel, second comparison means for comparing the amplitude of said control signal with a second signal of a second predetermined amplitude, and means responsive to said second comparison means for directing the recording of differing ionized constituents of said gaseous stream to a second readout channel.

2. A multichannel readout mass spectrometer according to claim 1 further including means for effecting readout of said plurality of constituents upon a common channel, means for independently sensing upon said common channel interval of a differing readout channel, and means for correlating the recording interval of said differing readout channel with a constituent of a given mass desired to be recorded upon said differing readout channel.

3. A multichannel readout mass spectrometer according to claim 1 wherein means selectively passing ionized constituents of said gaseous stream comprise at least two elongated conductors disposed on opposite sides of said ionized stream and means for simultaneously applying DC and RF signals to said elongated conductors to effect a spiral trajectory in the ionized stream passing between said elongated conductors.

4. A multichannel readout mass spectrometer according to claim 3 wherein said control signal is a ramp voltage.