Abstract: A method for fabricating a quadrupole mass filter (QMF) or quadrupole ion trap (QIT) capable of generating a hyperbolic electric field. The method comprises: (a) cutting four elongate erodible metal workpieces axially at opposing extremities; (b) parallel mounting the four elongate erodible metal workpieces axially in an elongate slot in an insulating housing in a mutually spaced apart disposition such that an axial bore is formed therebetween whereby a first part of each elongate erodible metal workpiece is freely inward facing and the cutting forms a recess remote from the axis of the insulating housing; (c) electrically connecting the erodible metal workpieces; and (d) generating electrical discharges between the erodible metal workpiece and a wire electrode as the wire electrode passes through the axial bore to erode the erodible metal of the first part of the erodible metal workpiece to a hyperbolic profile.

Abstract: The present invention relates to a method for fabricating a quadrupole mass filter (QMF) or a quadrupole ion trap (QIT).