Mass spectrometer leak detector and ion source therefor having magnetic focusing means

Claim 1

AN IMPROVED MASS SPECTROMETER COMPRISING IN COMBINATION: (A) A BODY MEMBER HAVING OPPOSED FACES AND NARROW SIDE WALLS ENCLOSING A GAS EVACUATED INTERNAL CAVITY, A GAS FLOW INLET IN THE SURFACE OF THE BODY LEADING TO THE CAVITY AND ADAPTED TO BE CONNECTED TO A SYSTEM TO BE INVESTIGATED, AUXILIARY OPENINGS IN THE SURFACE OF THE BODY ALSO LEADING TO THE CAVITY, (B) DEMOUNTABLE VACUUM CLOSURE MEANS COVERING SAID AUXILIARY OPENINGS AND SUPPORTING A COLD CATHODE DISCHARGE GUAGE, ION SOURCE ELECTRODES AND A COLLECTOR IN SAID CAVITY, (C) MAGNET MEANS PROVIDING MAGNETIC FIELDS THROUGH THE GUAGE, THROUGH THE ION SOURCE, AND THROUGH A PORTION OF THE CAVITY BETWEEN THE IRON SOURCE AND COLLECTOR, AND COMPRISING OPPOSED POLE PLATES EXTERNAL OF THE GUAGE AND STRADDLING THE FACES OF THE BODY WITH PAIRS OF POLE EXTENSIONS EXTENDING INWARDLY FROM THE PLATES TO PROVIDE SAID FIELDS AND WHEREIN THE POLE EXTENSION WHICH PROVIDE SAID ION SOURCE FIELD ARE ADJUSTABLE TO VARY THE SENSITIVITY OF THE ION SOURCE.