Mass filter with sheet electrodes on each side of the analyzer rod that intersect on the ion beam axis

Claim 1

AN ELECTRIC MASS FILTER, COMPRISING AN EVACUABLE ENVELOPE, AN ION SOURCE, COLLECTOR ELECTRODE MEANS SPACED FROM AND DEFINING WITH SAID ION SOURCE AN ION PATH AXIS IN SAID ENVELOPE, PAIR OF ELONGATED ANALYZER ELECTRODE RODS EXTENDING BETWEEN SAID SOURCE AND SAID COLLECTOR ELECTRODE MEANS IN AXIALLY SPACED RELATION TO BOTH AND RADIALLY SPACED FROM SAID AXIS FOR APPLYING AN ALTERNATING ELECTRIC FIELD FOR LATERAL DEFLECTION OF IONS, SAID ANALYZER ELECTRODE RODS BEING SYMMETRICALLY POSITIONED TO AT LEAST TWO SYMMETRY PLANES THROUGH SAID AXIS, INTERMEDIATE SHEET ELECTRODES INTERMEDIATE TWO OF SAID SYMMETRY PLANES, SAID SHEET ELECTRODES HAVING A SUBSTANTIALLY UNIFORM THICKNESS SMALLER THAN THAT OF SAID ANALYZER ELECTRODE RODS AND EXTENDING RADIALLY THROUGH AND FROM SAID AXIS AND BETWEEN SAID ANALYZER ELECTRODE RODS, SAID ION SOURCE BEING MOUNTED ON SAID AXIS, SAID SHEET ELECTRODES BEING AT LEAST AS LONG AS SAID RODS IN AXIAL LENGTH, AND VOLTAGE SUPPLY MEANS CONNECTED TO SAID ANALYZER ELECTRODE RODS FOR SUPPLYING DETERMINED VOLTAGES TO SAID ANALYZER ELECTRODE RODS.