Gate for modulating beam of charged particles and method for making same
AssigneeThe Board of Trustees of the Leland Stanford Junior University
InventorsJoel R. Kimmel, Friedrich Engelke, Richard N. Zare
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Abstract
Bradbury-Nielson gates for the modulation of beams of charged particles, particularly ion beams in mass spectrometry, have been produced with an adjustable wire spacing down to 0.075 mm or a smaller spacing. The gates are robust, they can be fabricated in less than 3 hours, and the method of production is reproducible. In time-of-flight mass spectrometers, fine wire spacing leads to improvements in mass resolution and modulation rates. Gates that were produced using this new method have been installed in a Hadamard transform time-of-flight mass spectrometer in order to demonstrate their utility.
Claims28
A method for making a gate for electrically modulating a beam of charged particles, comprising:
- providing a body having a surface and grooves on the surface, a hole in the body through the surface, and at least a first and a second electrical contact on the body;
- winding an electrically conducting wire under tension onto the grooves so that a first set of portions of the wire in grooves that are not adjacent to one another is in contact with the first electrical contact, and a second set of portions of the wire is in at least some of the remaining grooves and in contact with the second electrical contact, and so that the two sets are electrically isolated from each other;
- and
- attaching the first set of portions of the wire to the first electrical contact and the second set of portions of the wire to the second electrical contact so that the portions of the first and second sets of the wire passing over a side of the hole at the surface are fixed in position, wherein the grooves and the surface are such that the two sets of wires are substantially coplanar at the hole.
A gating apparatus for electrically modulating a beam of charged particles, comprising:
- a body having a surface and grooves on the surface, a hole in the body through the surface, and at least a first and a second electrical contact on the body;
- a first set of electrically conducting wires located in grooves that are not adjacent to one another, said first set being in electrical contact with the first electrical contact;
- and
- a second set of electrically conducting wires located in at least some of the remaining grooves on the surface, said second set being in electrical contact with the second electrical contact, the two sets being electrically isolated from each other, wherein the two sets of portions of wires pass over a side of the hole at the surface and the grooves and the surface are such that the two sets of wires are substantially co-planar at the hole.
A method comprising:
- winding electrically conducting wire under tension about a body, the body having a surface and a plurality of wire-positioning features along the surface, said features comprising grooves on the surface, the wires wound so that the positioning features comprising grooves maintain a first set of portions of the wire interspersed with a second set of portions of the wire across the surface;
- electrically isolating the two sets from each other and attaching the first set of portions of the wire to a first electrical contact and the second set of portions of the wire to a second electrical contact;
- and
- modulating a beam of charged particles transiting a hole through the surface of the body using electrical potentials applied to the first and second electrical contacts while the portions of the first and second sets of the wire span the hole and are substantially co-planar at the hole.
A gating apparatus for electrically modulating a beam of charged particles, comprising:
- a body having a surface and a hole in the body through the surface and grooves on the surface;
- a first set of electrically conducting wires in the grooves in electrical contact with a first electrical contact;
- and
- a second set of electrically conducting wires in the grooves interspersed with the first set with a spacing between adjacent wires of the two sets being about 0.1 mm or less, said second set being in electrical contact with a second electrical contact, the two sets being electrically isolated from each other, wherein the two sets of portions of wires span the hole along the surface such that the two sets of wires are substantially co-planar at the hole.
Dependencies are inferred from the claim text.