Claims
- 1. An array of elements forming a quadrupole of the type which applies a strong focusing force to a beam of charged particles, comprising:
- (a) four substantially identical elements, each comprising an electrically conductive support rod and an electrically conductive electrode, the electrode having a longitudinal axis and a cross-sectional area orthogonal to the longitudinal axis which is greater than the cross-sectional area of the rod, the electrode being mounted on and in electrical contact with the rod with the longitudinal axis of the electrode substantially orthogonal to the axis of the rod, the electrodes having planar faces at each end orthogonal to the longitudinal axis of the electrode, and the electrodes being mounted asymmetrically on the rods;
- (b) means for positioning the electrodes in a substantially square array to form a quadrupole with the axes of the electrodes being substantially parallel, the faces of the electrodes being aligned in two planes orthogonal to the longitudinal axes of the electrodes, the rods connected to one pair of opposite electrodes forming a first parallel pair and the rods connected to the other pair of opposite electrodes forming a second parallel pair, the first pair of rods being substantially orthogonal to the second pair and spaced from the second pair due to asymmetrical mounting of the electrodes, the rods being so positioned that no rod will obstruct the passage of a beam through the volume, defined by the quadrupole, wherein the beam may be exposed to strong focusing forces and so that a plan view of the array taken orthogonally to the longitudinal axes of the electrodes would show the sides of the square formed by said electrodes being at an angle of approximately 45 degrees with the rods, the positioning means further comprising:
- (b1) an insulator; and
- (b2) first and second conductive terminals, each terminal having two ends, the terminals being electrically and mechanically connected to the first and second pairs of rods respectively and being mechanically joined but electrically insulated at one end by the insulator, whereby the elements are held in position to form the quadrupoles and each of the pairs of opposite electrodes may be connected to sources of electrical potential so that they have opposite polarity.
- 2. An element array as claimed in claim 1, further comprising second, third, and fourth insulators, and third and fourth conductive terminals, each terminal having two ends and being mechanically joined at one end, but electrically isolated from each other by means of one of the insulators and said terminals being joined similarly at their other end to the free ends of the first and second terminals by the remaining insulators, the third terminal being positioned generally opposite the first terminal to receive the opposite end of the rods connected to the first terminal, and the fourth terminal being positioned opposite the second terminal to receive the opposite ends of the rods connected to the second terminal.
- 3. An element array as claimed in claim 2, wherein each of the elements further comprise a plurality of substantially identical electrodes similarly oriented and mounted on the rods, and the array further comprises a plurality of identical elements, the plurality of elements being divided into a first and a second group, the first group being positioned with their rods in the same plane as and connected to the same terminals as the first pair of rods, while the rods of the second group are positioned in the same plane as and connected to the same terminals as the second pair of rods, the plurality of electrodes on each rod being spaced along the rods and the rods being spaced along the terminals to form a plurality of quadrupoles each having a square array with the faces of the electrodes lying in the first and second planes.
BACKGROUND OF THE INVENTION
The United States Government has rights in this invention pursuant to Contract Number DE-AC02-76CH00016, between the United States Department of Energy and Associated Universities, Inc.
US Referenced Citations (4)