Electron impact ion source for mass spectrometer with coincident electron beam and ion beam axes

Claim 1

A MASS SPECTROMETER UTILIZING A STREAM OF IONS GENERATED BY MEANS OF A STREAM OF ELECTRONS MOVING PARALLEL TO THE OPTIC AXIS OF SAID SPECTROMETER, SAID STREAM OF IONS MOVING COLINEARLY WITH RESPECT TO SAID STREAM OF ELECTRONS, COMPRISING AN IONIZABLE MEDIUM, A SOURCE OF ELECTRONS DISPOSED ON SAID OPTIC AXIS, AND A PLURALITY OF AXIALLY DISPLACED, APERTURED ELECTRODES IN SAID IONIZABLE MEDIUM, SAID ELECTRODES INCLUDING SEQUENTIALLY: A FIRST ELECTRON FOCUSING ELECTRODE, AN ELECTRON ACCELERATING ELECTRODE AXIALLY DISPLACED FROM SAID SOURCE OF ELECTRONS, A SECOND ELECTRON FOCUSING ELECTRODE, SAID FIRST AND SECOND FOCUSING ELECTRODES AND SAID ELECTRON ACCELERATING ELECTRODE COACTING TO FOCUS ELECTRONS FROM SAID SOURCE OF ELECTRONS INTO A STREAM CONVERGING AT A SITE ON SAID AXIS AT A GIVEN DISTANCE REMOTE FROM SAID ELECTRON ACCELERATING ELECTRODE, A VOLTAGE DEFINING ELECTRODE AT SAID SITE, SAID VOLTAGE DEFINING ELECTRODE DEFINING THE INITIAL ENERGY OF IONS FORMED IN A REGION IN THE VICINITY OF SAID SITE; AN ION FOCUSING ELECTRODE AND AN OBJECT ELECTRODE, SAID ION FOCUSING, OBJECT AND VOLTAGE DEFINING ELECTRODES COACTING TO EXTRACT, FOCUS AND ACCELERATE THE IONS FORMED IN SAID REGION INTO A STREAM OF IONS MOVING PARALLEL TO SAID GIVEN AXIS AND BEYOND SAID OBJECT ELECTRODE AND FOR PREVENTING ELECTRONS WITHIN AND IONS FORMED WITHIN THE REGION BETWEEN SAID VOLTAGE DEFINING AND OBJECT ELECTRODES FROM MOVING BEYOND SAID OBJECT ELECTRODE; SAID ELECTRON ACCELERATING ELECTRODE, SECOND ELECTRON FOCUSING ELECTRODE AND SAID VOLTAGE DEFINING ELECTRODE FURTHER COACTING TO PREVENT IONS FORMED IN THE REGION BETWEEN SAID ELECTRON ACCELERATING AND VOLTAGE DEFINING ELECTRODES FROM EMERGING FROM SAID REGION; SAID ELECTRON ACCELERATING ELECTRODE AND SAID SOURCE OF ELECTRONS FURTHER COACTING TO PREVENT IONS FORMED IN THE REGION BETWEEN SAID ELECTRON ACCELERATING ELECTRODE AND SAID SOURCE OF ELECTRONS FROM EMERGING FROM SAID REGION; MAGNETIC MEANS DISPOSED ALONG SAID AXIS FOR DEFLECTING THE IONS IN SAID STREAM OF IONS IN ACCORDANCE WITH THE MOMENTUM THEREOF, AND ION CURRENT MEASURING MEANS FOR MEASURING THE CURRENT IN THE DEFLECTED STREAM OF IONS.