QUADRUPOLE MASS FILTER

摘要

Apparatus and method to improve the filtering action of a quadrupole mass filter by reducing a precursor fault caused by au uymmetric electrical fleld between a pair of opposing electrode rods in a y-axis of the quadrupolo mass filter. Processing means for processing detector data determine the filtering action of the quadrupole mass filter by chxking for a precursor fault. If a precursor fault is detected then power supply control means introduce an AC potential differcnce across the electrode rods in the y-axis in order to reduce asymmetry in the electrical field ia the y-axis.