Patent ID: 7501623

Claim:
An electrode structure for manipulating ions, comprising: a plurality of electrodes coaxially disposed about a central axis, each electrode having an axial length extending generally in the direction of the central axis, each electrode including a first axial end, a second axial end and segmented into a first end section, a central section and a second end section axially spaced therebetween, an outside surface generally facing away from an interior space of the electrode structure, and an inside surface generally facing the interior space and axially extending from the first axial end to the second axial end, wherein: at least one of the electrodes is an apertured electrode having an aperture radially extending from the inside surface to the outside surface; and the inside surface of the apertured electrode includes a surface profile, the surface profile includes an apical region generally centered about the aperture and axially extending from the first axial end to the second axial end, the surface profile in the apical region is uniform along the axial direction from the first axial end to the second axial end of the central section of the apertured electrode, and the uniformity of the surface profile continues along the axial direction over at least a portion of the first end section of the apertured electrode nearest to the first axial end of the center section and over at least a portion of the second end section of the apertured electrode nearest to the second axial end of the center section.