Electric mass filter

Claim 1

AN ELECTRIC MASS-FILTER CELL, PARTICULARLY FOR MEASURING PARTIAL PRESSURE IN VACUUM OF 10-2 TO 10-6 MM. HG, COMPRISING AN ENVELOPE TUBE OF METAL AND TWO ENVELOPE END PORTIONS SEALING THE REPECTIVE ENDS OF SAID TUBE, SAID TUBE HAVING A LATERAL NECK FOR CONNECTION TO A SUPPLY OF GAS TO BE INVESTIGATED; AN ION SOURCE MOUNTED ON ONE OF SAID END PORTIONS AND FORMING A FIRST STRUCTURAL UNIT TOGETHER THEREWITH; A COLLECTOR ELECTRODE MOUNTED ON SAID OTHER END PORTION AND FORMING A SECOND STRUCTURAL UNIT TOGETHER THEREWITH; AND A GROUP OF ANALYZER ELECTRODES CONSISTING OF ELONGATED RODS PARALLEL TO THE AXIS OF SAID TUBE AND DISTRIBUTED ABOUT SAID AXIS, SAID RODS BEING MOUNTED ON SAID TUBE IN INSULATED RELATION TO SAID SOURCE AND COLLECTOR ELECTRODE AND TUBE, AND SAID RODS FORMING TOGETHER WITH SAID TUBE A THIRD STRUCTURAL UNIT; SAID THREE UNITS BEING INDIVIDUALLY ADJUSTABLE PRIOR TO BEING ASSEMBLED AND BEING FASTENED AND SEALED TOGETHER IN COAXIAL ALIGNMENT WHEN ASSEMBLED, SAID METAL TUBE AND SAID ONE END PORTION HAVING RESPECTIVE METAL FLANGES RELEASABLY AND VACUUM-TIGHTLY JOINED WITH EACH OTHER, AN ION ENTRANCE DIAPHRAGM MOUNTED ON SAID ONE END PORTION COAXIALLY IN FRONT OF THE ION OUTLET OF SAID COURCE, SAID DIAPHRAGM BEING AXIALLY SPACED FROM SAID OUTLET A DISTANCE AT MOST EQUAL TO ONE-HALF OF THE MUTUAL SPACING OF SAID ANALYZER RODS.