Ion source for a mass spectrometer

Claim 2

AN ION SOURCE, SAID SOURCE BEING CLOSED AT ONE END AND OPEN AT THE OPPOSITE END FOR DISCHARGE OF AN ION STREAM, SAID SOURCE COMPRISING A GAS CONNECTION FOR SUPPLY OF A GAS TO BE IONIZED, AN ELECTRON-EMITTING CATHODE, A LONG DRIFT TUBE DISPOSED ON THE SIDE OF THE CATHODE REMOTE FROM THE DISCHARGE END OF THE SOURCE, A MAGNET SURROUNDING THE DRIFT TUBE, A FOCUSING ELECTRODE BETWEEN THE CATHODE AND THE DRIFT TUBE, THE OPPOSITE SIDE OF THE CATHODE LEADING TO THE OPEN END OF THE SOURCE HAVING FOCUSING AND ACCELERATING ELECTRODES, MEANS TO POLARIZE THE DRIFT TUBE POSITIVELY RELATIVE TO THE CATHODE, AND MEANS TO APPROPRIATELY POLARIZE THE FOCUSING AND ACCELERATING ELECRODES, SAID CATHODE BEING THE SOLE SOURCE OF ELECTRONS, THE ARRANGEMENT BEING SUCH THAT AN ELECTRON STREAM FLOWS IN REVERSE DIRECTION THROUGH THE DRIFT TUBE TOWARD THE CLOSED END OF THE SOURCE, AND RESULTING IONS FLOW IN A FORWARD DIRECTION OPPOSITE TO THE DIRECTION OF THE ELECTRON STREAM AND THROUGH THE FOCUSING AND ACCELERATING ELECTRODES TOWARD THE DISCHARGE END OF THE SOURCE.

Claim 3

AN ION SOURCE FOR USE IN A MASS SPECTROMETER, SAID SOURCE BEING CLOSED AT ONE END AND OPEN AT THE OPPOSITE END FOR DISCHARGE OF AN ION STREAM INTO THE SPECTROMETER TUBE, SAID SOURCE COMPRISING A GAS CONNECTION FOR SUPPLY OF A GAS TO BE IONIZED, AN ELECTRON-EMITTING CATHODE, A LONG DRIFT TUBE DISPOSED ON THE SIDE OF THE CATHODE REMOTE FROM THE DISCHARGE END OF THE SOURCE, A MAGNET SURROUNDING THE DRIFT TUBE, A FIRST FOCUSING ELECTRODE BETWEEN THE CATHODE AND THE DRIFT TUBE, THE OPPOSITE SIDE OF THE CATHODE LEADING TO THE DISCHARGE END OF THE SOURCE HAVING IN SUCCESSION A SECOND FOCUSING ELECTRODE AND AN ACCELERATING ELECTRODE AND A THIRD FOCUSING ELECTRODE, MEANS TO HEAT THE CATHODE, MEANS TO POLARIZE THE DRIFT TUBE POSITIVELY RELATIVE TO THE CATHODE, AND MEANS TO POLARIZE THE FIRST AND SECOND FOCUSING ELECTRODES AT A POSITIVE POTENTIAL LESS THAN THAT OF THE DRIFT TUBE, AND TO POLARIZE THE THIRD FOCUSING ELECTRODE MORE NEGATIVELY THAN THE CATHODE, AND THE ACCELERATING ELECTRODE MORE NEGATIVELY THAN THE THIRD FOCUSING ELECTRODE, SAID CATHODE BEING THE SOLE SOURCE OF ELECTRONS, THE ARRANGEMENT BEING SUCH THAT AN ELECTRON STREAM FLOWS IN REVERSE DIRECTION THROUGH THE DRIFT TUBE TOWARD THE CLOSED END OF THE SOURCE, AND RESULTING IONS FLOW IN A FORWARD DIRECTION OPPOSITE TO THE DIRECTION OF THE ELECTRON STREAM AND THROUGH THE FOCUSING AND ACCELERATING ELECTRODES TOWARD THE DISCHARGE END OF THE SOURCE.

Claim 4

AN ION SOURCE FOR USE IN A MASS SPECTROMETER, SAID SOURCE BEING CLOSED AT ONE END AND OPEN AT THE OPPOSITE END FOR DISCHARGE OF AN ION STREAM INTO THE SPECTROMETER TUBE, SAID SOURCE COMPRISING A GAS CONNECTION FOR SUPPLY OF A GAS TO BE IONIZED, AN ELECTRON-EMITTING CATHODE, A LONG DRIFT TUBE DISPOSED ON THE SIDE OF THE CATHODE REMOTE FROM THE DISCHARGE END OF THE SOURCE, A MAGNET SURROUNDING THE DRIFT TUBE, A FIRST FOCUSING ELECTRODE BETWEEN THE CATHODE AND THE DRIFT TUBE, THE OPPOSITE SIDE OF THE CATHODE LEADING TO THE DISCHARGE END OF THE SOURCE HAVING IN SUCCESSION A SECOND FOCUSING ELECTRODE AND AN ACCELERATING ELECTRODE AND A THIRD FOCUSING ELECTRODE, MEANS TO HEAT THE CATHODE, MEANS TO POLARIZE THE DRIFT TUBE POSITIVELY RELATIVE TO THE CATHODE, AND MEANS TO POLARIZE THE FIRST AND SECOND FOCUSING ELECTRODES AT A POSITIVE POTENTIAL LESS THAN THAT OF THE DRIFT TUBE, AND TO POLARIZE THE THIRD FOCUSING ELECTRODE MORE NEGATIVELY THAN THE CATHODE, AND THE ACCELERATING ELECTRODE MORE NEGATIVELY THAN THE THIRD FOCUSING ELECTRODE, SAID CATHODE BEING THE SOLE SOURCE OF ELECTRONS, THE ARRANGEMENT BEING SUCH THAT AN ELECTRON STREAM FLOWS IN REVERSE DIRECTION THROUGH THE DRIFT TUBE TOWARD THE CLOSED END OF THE SOURCE, AND RESULTING IONS FLOW IN A FORWARD DIRECTION OPPOSITE TO THE DIRECTION OF THE ELECTRON STREAM AND THROUGH THE FOCUSING AND ACCELERATING ELECTRODES TOWARD THE DISCHARGE END OF THE SOURCE.