Universal quadrupole and method of manufacture

Abstract

The present invention provides a method and apparatus for formation of a quadrupole electrode assembly for a mass spectrometer. The quadrupole electrode assembly is comprised of an outer elongate tube having an internal and external surface where the outer elongate tube as the outermost structure may be used for supporting a vacuum and an electrode structure fused to the internal surface of the outer elongate tube. Typically there are four electrodes where each electrode includes an arced region having a conductive surface where the arcs are aligned in parallel opposing pairs equidistant from a central axis. In the preferred embodiment, the four electrode structures are four cylindrical glass tubes where the curvature of the arc approximates a hyperbola. At least a portion of the surface of the arc 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 structure.