Analytical apparatus with variable energy ion beam source

A source to produce a variable energy ion beam, comprising:

• a. a repeller electrode;
• b. first, low energy, alignment electrode, having a first alignment slit therein and coacting with said repeller electrode to define an ion-forming region therebetween;
• c. inlet means for introducing gas into the ion-forming region;
• d. means for forming an electron beam in said ion-forming region;
• e. an extraction electrode with an extraction slit therein;
• f. second, high energy, alignment electrode having a second alignment slit therein;
• g. an entrance electrode having an entrance slit therein, all of the aforesaid electrodes being in sequential order and all of the aforesaid slits being aligned to define a trajectory between the electron beam and the entrance slit;
• h. means for maintaining said repeller electrode at a constant potential relative to said first alignment electrode and said first alignment electrode at a constant positive potential relative to said extraction electrode;
• i. means for maintaining said second alignment electrode at a potential more negative than the proportional to that of said extraction electrode;
• and
• j. means to maintain said extraction electrode at a positive potential relative to said entrance electrode and to vary its potential relative to said entrance electrode.

An analytical apparatus comprising:

• a. a gas chromatograph comprising a gas chromato-graphic column with a gas inlet and a gas outlet;
• b. a mass spectrometer comprising a variable energy ion beam source, a magnetic sector for deflecting the ions in the ion beam according to their momentum and detector means for detecting those ions within the ion beam which have been deflected by a given angle by the magnetic sector, said ion beam source comprising:
• i. a repeller electrode;
• ii. first, low energy, alignment electrode, having a first alignment slit therein and coacting with said repeller electrode to define an ion-forming region therebetween;
• iii. inlet means for introducing gas into the ion-forming region;
• iv. means for forming an electron beam in said ion-forming region;
• v. second, high energy, alignment electrode having a second alignment slit therein;
• vi. an entrance electrode having an entrance slit therein separating said ion beam source from said magnetic sector, all of the aforesaid electrodes being in sequential order and all of the aforesaid slits being aligned to define a straight path between the electron beam and the entrance slit;
• vii. means for maintaining said repeller electrode at a constant potential relative to said first alignment electrode;
• viii. means for maintaining said second alignment electrode at a potential more negative than and proportional to that of said first alignment electrode;
• ix. means to maintain said first alignment electrode at a positive potential relative to said entrance electrode and to vary its potential relative to said entrance electrode;
• and
• c. an interface for connecting the gas outlet of said chromatograph to said inlet means of said ion beam source.

An analytical apparatus comprising:

• a. a gas chromatograph comprising a gas chromatographic column with a gas inlet and a gas outlet;
• b. a mass spectrometer comprising a variable energy ion beam source, a magnetic sector for deflecting the ions in the ion beam according to their momentum and detector means for detecting those ions within the ion beam which have been deflected by a given angle by the magnetic sector, said ion beam source comprising:
• i. a repeller electrode;
• ii. first, low energy, alignment electrode, having a first alignment slit therein and coacting with said repeller electrode to define an ion-forming region therebetween;
• iii. inlet means for introducing gas into the ion-forming region;
• iv. means for forming an electron beam in said ion-forming region;
• v. an extraction electrode with an extraction slit therein;
• vi. second, high energy, alignment electrode having a second alignment slit therein;
• vii. an entrance electrode having an entrance slit therein separating said ion beam source from said magnetic sector, all of the aforesaid electrodes being in sequential order and all of the aforesaid slits being aligned to define a straight path between the electron beam and the entrance slit;
• viii. means for maintaining said repeller electrode at a constant potential relative to said first alignment electrode and said first alignment at a constant positive potential relative to said extraction electrode;
• ix. means for maintaining said second alignment electrode at a potential more negative than and proportional to that of said extraction electrode;
• x. means to maintain said extraction electrode at a positive potential relative to said entrance electrode and to vary its potential relative to said entrance electrode;
• and
• c. an interface for connecting the gas outlet to said chromatograph to said inlet means of said ion beam source.

An analytical apparatus comprising:

• a. a gas chromatograph comprising a gas chromatographic column with a gas inlet and a gas outlet;
• b. a mass spectrometer comprising a variable energy ion beam source, a magnetic sector for deflecting the ions in the ion beam according to their momentum, and detector means for detecting those ions within the ion beam which have been deflected by a given angle by the magnetic sector, said detector means comprising:
• i. an ion detector;
• ii. an exit plate having an exit slit separating said magnetic sector from said ion detector;
• iii. a pair of opposed deflector electrodes disposed within said magnetic sector adjacent said exit plate, one of said deflector electrodes being located on either side of the ion beam;
• and
• iv. means for applying an AC potential to said deflector plate;
• and
• c. an interface for connecting the gas outlet of said chromatograph to said ion beam source.

An analytical apparatus comprising:

• a. a gas chromatograph comprising a gas chromatographic column with a gas inlet and a gas outlet;
• b. a mass spectrometer comprising a variable energy ion beam source, a magnetic sector for deflecting the ions in the ion beam according to their momentum, and detector means for detecting those ions within the ion beam which have been deflected by a given angle by the magnetic sector;
• and
• c. an interface for connecting the sample gas outlet of said chromatograph to said ion beam source, said interface comprising:
• i. an electrically nonconductive interface conduit connecting the sample gas outlet of said chromatograph to said ion beam source,
• ii. a restriction disposed in said interface conduit to create a pressure drop in said interface conduit between said gas chromatograph and said mass spectrometer,
• iii. a sample gas enricher disposed in said interface conduit downstream from said restriction for enriching the concentration of sample relative to carrier in the gas flowing through said interface conduit,
• iv. a first electrical conductor disposed relative to the low pressure region of said interface conduit, and
• v. means to maintain the potential of said first electrical conductor at about the potential of said ion beam source.