Process for the manufacture of a multipolar elongate-electrode l

Details Process for the manufacture of a multipolar elongate-electrode l Process for the manufacture of a multipolar elongate-electrode l

1994-02-03

1995-01-24

Berman, Jack I.

Radiant energy

Ionic separation or analysis

Cyclically varying ion selecting field means

250396R, H01J 4942, H01J 318

Patent

active

053844610

DESCRIPTION:

BRIEF SUMMARY
This invention comprises an improved method of manufacture of multipolar elongate electrode structures suitable for electrostatically focusing or mass-filtering a beam of charged particles. The method is particularly suitable for the manufacture of a quadrupole mass filter.
Electrostatic lenses comprising a plurality of parallel elongate electrodes are in common use for focusing and/or filtering beams of charged particles. Typically they comprise four or six rod electrodes disposed parallel to and equidistant from an axis along which the particles are travelling. The rods are insulated from one another so that AC or DC potentials may be applied to them according to the required purpose. The elongate electrodes may be cylindrical or may have a hyperbolic cross-section. Other geometries comprising more electrodes (e.g. 8 or 12), or a single rod electrode and a `V` angled electrode (a "monopole" mass filter) are also known, and may be manufactured according to this method.
In all such lenses or filters the electrodes must comprise electrically conductive material and means must be provided for holding them in place while providing electrical insulation between them. Particularly in the case of quadrupole mass filters the electrodes must be precisely aligned to ensure high transmission efficiency at high mass resolution. Although several of the prior methods of construction described below are conventionally used to manufacture elongate electrode structures, there remains a need for a lower cost method of production, particularly of high performance quadrupole mass filters.
Most quadrupole mass filters are constructed from four accurately ground cylindrical or hyperbolic electrodes which are supported by two or more ceramic ring insulators comprising accurately formed locations for the electrodes (see, for example, U.S. Pat. No. 4,032,782, SU patent 868,885, GB patent 2,138,201 and JP patent application 58-204464). Manufacture of the ring insulators is however difficult and considerable time is required to align the rods when the filter is assembled. In order to reduce the amount of precision machining of ceramic components, several prior designs incorporate metallic end-plates to which the electrodes are attached through insulated washers, bushes or pins (for example as disclosed in JP patent application 62-103956 and SU patent 469479), or by specially shaped insulators (SU 989614, 989615). In other forms of construction, electrodes made of an insulating material coated with a conductive film may be fitted to metallic endplates, as disclosed in U.S. Pat. Nos. 3,699,330 and 3,793,063. U.S. Pat. No. 4,870,283 discloses metallic electrodes mounted in locations machined in a metallic yoke but spaced from the yoke by a thin insulating film. Further methods comprise spacing the electrodes apart by saphire balls which locate in dimples formed in the electrodes (Munro, Rev. Sci. Instrum, 1967, vol. 38 (10) pp 1532), spacing the electrodes apart by precision machined cylindrical insulators disposed around the inside of a cylinder (Okayama, Nucl. Instrum. Methods in Phys. Res. 1990 vol. A298 pp 488-495), and the use of ceramic ring insulators without locations in conjunction with non-circular electrodes which have an outwardly facing radius of curvature equal to the inside radius of the ring insulator (U.S. Pat. No. 3,553,451). A ceramic ring insulator without locations is also used in the structure disclosed in SU 694917, wherein a metallic end-plate for locating all the electrodes is brazed inside a ring insulator and subsequently cut into sections (typically by spark erosion) to provide electrical insulation between the electrodes. In another variation using ceramic ring insulators (U.S. Pat. No. 3,840,742) a method of locating and fixing hyperbolic electrodes is disclosed.
A different approach is to form the structure of the lens or mass filter from an insulator and provide the conductive electrodes by coating a conductive material on the structure as required. GB patent 1,367,638 discloses a quadrupole filter form

REFERENCES:
patent: 3553451 (1971-01-01), Uthe
patent: 4117321 (1978-09-01), Meyer

Affiliated with

Also associated with

Rating

Process for the manufacture of a multipolar elongate-electrode l does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Process for the manufacture of a multipolar elongate-electrode l, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for the manufacture of a multipolar elongate-electrode l will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-1469608