Quadrupole mass filters with introductory ion accelerating field proportional to thequadrupole electric field

Claim 1

IN A MULTI-POLE MASS FILTER HAVING A PLURALITY OF SUBSTANTIALLY PARALLEL PRIMARY ELECTRODES SPACED SYMMETICALLY ABOUT A CENTRAL AXIS, MEANS FOR IMPOSING AN EXCITATION VOLTAGE ON THE PRIMARY ELECTRODES INCLUDING MEANS FOR APPLYING A D.C. VOLTAGE TO PRODUCE A STATIC MULTI-POLE ELECTRIC FIELD COMPONENT BETWEEN THE PRIMARY ELECTRODES AND MEANS FOR APPLYING AN A.C. VOLTAGE TO PRODUCE AN ALTERNATING MULTI-POLE ELECTRIC FIELD COMPONENT BETWEEN THE PRIMARY ELECTRODES, A SOURCE OF IONS LOCATED OUTSIDE THE MULTI-POLE FIELD, AND PROPELLING ELECTRODE MEANS LOCATED IN THE REGION OF THE SOURCE OF IONS, THE IMPROVEMENT WHICH COMPRISES MEANS FOR APPLYING A POTENTIAL TO THE PROPELLING ELECTRODE MEANS FOR INJECTING IONS FROM THE SOURCE INTO THE MASS FILTER AND MEANS FOR MAINTAINING THE POTENTIAL APPLIED TO THE PROPELLING ELECTRODE MEANS UNIFORMLY PROPORTIONAL TO THE MULTI-POLE ELECTRIC FIELD TO CAUSE THE ENERGY WITH WHICH THE IONS ARE INJECTED INTO THE MASS FILTER TO BE UNIFORMLY PROPORTIONAL TO THE EXCITATION VOLTAGE.