Universal quadrupole and method of manufacture

Abstract

A quadrupole electrode assembly for a mass spectrometer and a method for forming the electrode assembly are provided. The quadrupole electrode assembly is comprised of an elongate outer tube, having an internal surface and an external surface wherein the outer tube is the outermost structure of the electrode assembly and supports a vacuum, and an electrode structure fused to the internal surface of the outer tube. Typically, there are four electrodes where each electrode includes an arced region having a conductive surface. The arced regions of the electrodes are aligned in parallel opposing pairs equidistant from a central axis. The four electrode structures can be four cylindrical glass tubes where the curvature of the arced region approximates a hyperbola. At least a portion of the surface of the arced region is a conductive region typically formed by applying a metal coating to the surface of the glass tube. The arced region of the electrode may be a hyperbola formed by placing the electrode structure in proximity to a first hyperbolic surface and modifying the shape of the electrode structure by heating the structure to its softening point. In response to a pressure differential, the structure expands to conform to the first hyperbolic surface.