Vacuum pumps

Claim 1

AN IONISATION AND EVAPORATION VACUUM PUMP, COMPRISING A SEALED CYLINDRICAL ENCLOSURE MADE OF A NONMAGNETIC MATERIAL, AN INLET ON SAID ENCLOSURE FOR CONNECTING SAID PUMP TO A STRUCTURE TO BE EVACUATED, A COATING ON THE INSIDE WALL OF SAID ENCLOSURE, SAID COATING HAVING GOOD GAS ABSORPTION PROPERTIES, A CYLINDRICAL GRID STRUCTURE OPEN AT ONE END ARRANGED AXIALLY WITHIN AND ELECTRICALLY INSULATED FROM SAID ENCLOSURE, SAID GRID STRUCTURE CONSISTING OF A PLURALITY OF RODS DISPOSED IN SQUIRREL-CAGE FASHION ALONG THE GENERATORS OF A CYLINDER, AND A PLURALITY OF RINGS SECURED TO AND WITHIN SAID RODS IN PARALLEL AXIALLY SPACED RELATIONSHIP, THE OUTER DIAMETER OF SAID GRIP STRUCTURE BEING OF SUCH SIZE AS TO LEAVE A GAP BETWEN SAID INNER WALL OF SAID ENCLOSURE, MEANS FOR SUPPORTING SAID GRID STRUCTURE, MEANS FOR HEATING SAID GRID STRUCTURE, SAID GRID STRUCTURE BEING MADE OF A MATERIAL HAVING AT LEAST A COATING OF A METAL TO BE EVAPORATED, MEANS FOR APPLYING A POTENTIAL DIFFERENCE BETWEEN SAID GRID STRUCTURE AND SAID ENCLOSURE TO CAUSE SAID ENCLOSURE TO FUNCTION AS A CATHODE IN RELATION TO SAID GRID STRUCTURE, SAID POTENTIAL DIFFERENCE BEING OF A MAGNITUDE TO SET UP AN ELECTRICAL FIELD BETWEEN THE WALL OF SAID ENCLOSURE AND SAID GRID AND TO SET UP AN ELECTRICAL CHARGE THEREBETWEEN, AND MAGNET MEANS LOCATED OUTSIDE SAID ENCLOSURE WITH THEIR POLE PIECES THEREUNTO ADJACENT FOR SETTING UP A MAGNETIC FIELD WITHIN SAID ENCLOSURE TO PREVENT ELECTRONS ISSUING FROM SAID INNER WALL OF SAID ENCLOSURE FROM FOLLOWING SAID ELECTRICAL FIELD AND REACHING SAID GRID STRUCTURE DURING THEIR FIRST TRAJECTORY, WHEREBY SAID ELECTRONS ARE CAUSED TO MAKE A LARGE NUMBER OF OSCILLATIONS BEFORE REACHING SAID GRID STRUCTURE.