Biased electrostatic deflector
First Claim
1. An angular electrostatic filter comprising:
- a top deflection plate set to a top voltage extending from an entrance side to an exit side, wherein the top deflection plate is planar;
a bottom deflection plate wherein at least a portion is substantially parallel to the top deflection plate and at least a portion is angled with respect to the top deflection plate, extending from the entrance side to the exit side, and set to a bottom voltage, wherein the bottom voltage is more negative than the top voltage, and wherein an electric field is generated between the top deflection plate and the bottom deflection plate;
an entrance electrode positioned at the entrance side of the filter and set to a first focus voltage; and
an exit electrode positioned at the exit side of the filter, wherein the exit electrode is set to a second focus voltage.
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Abstract
Angular electrostatic filters and methods of filtering that remove energy contaminants from a ribbon shaped ion beam are disclosed. An angular electrostatic filter comprises a top deflection plate and a bottom deflection plate extending from an entrance side to an exit side of the filter. The bottom deflection plate is substantially parallel to the top deflection plate and includes an angle portion. An entrance focus electrode is positioned on the entrance side of the filter and an exit focus electrode is positioned on the exit side of the filter and both serve to focus the ion beam. Edge electrodes are positioned between the top and bottom deflection plates and at sides of the filter to mitigate edge effects. A negative bias is also applied to the top and bottom plates to mitigate space charge by elevating the beam energy.
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Citations
19 Claims
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1. An angular electrostatic filter comprising:
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a top deflection plate set to a top voltage extending from an entrance side to an exit side, wherein the top deflection plate is planar; a bottom deflection plate wherein at least a portion is substantially parallel to the top deflection plate and at least a portion is angled with respect to the top deflection plate, extending from the entrance side to the exit side, and set to a bottom voltage, wherein the bottom voltage is more negative than the top voltage, and wherein an electric field is generated between the top deflection plate and the bottom deflection plate; an entrance electrode positioned at the entrance side of the filter and set to a first focus voltage; and an exit electrode positioned at the exit side of the filter, wherein the exit electrode is set to a second focus voltage. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A beamline assembly comprising:
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an accelerator component that selectively decelerates a ribbon shaped incoming ion beam; a tube focus component that further decelerates the ion beam and focuses the ion beam in a vertical direction; and an angular electrostatic filter that removes energy contaminants from the ion beam and directs the ion beam toward a target, wherein the angular electrostatic filter comprises; a top deflection plate extending from an entrance side to an exit side, wherein the top deflection plate is planar; a bottom deflection plate having a non-angled portion substantially parallel to the top deflection plate, extending from the entrance side toward the exit side and an angled portion extending from the non-angled portion to the exit side; an entrance electrode having an aperture that permits passage of the ion beam positioned at entrance side of the filter; an exit electrode positioned having an aperture that permits passage of the ion beam positioned at the exit side of the filter; a pair of edge electrodes extending from the entrance side to the exit side, substantially parallel to the top deflection plate and positioned midway between the top deflection plate and the bottom deflection plate; and an exit slit positioned downstream of the exit electrode that blocks energy contaminants and permits passage of ions having selected energies. - View Dependent Claims (11, 12, 13, 14, 15, 16)
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17. A method of removing energy contaminants form a ribbon shaped ion beam comprising:
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selecting an angle of deflection for a selected energy range for the ribbon shaped ion beam; applying an entrance focus field that focuses the ion beam in a vertical direction; applying an edge field that mitigates non-uniform fields near an end of a deflection field; and applying the deflection field according to the selected energy range at the selected angle of deflection, wherein applying the deflection field comprises applying a negative bias across a planar top deflection plate and a bottom deflection plate having an angled portion and a planar portion, wherein the ion beam travels between the top and bottom deflection plates, wherein the planar portion is parallel to the top deflection plates an is located at an entrance side of the deflection field. - View Dependent Claims (18, 19)
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Specification