Devices and methods for electrostatic ion beam deflection and filtration

1 . A device for electrostatic deflection of an ion beam, wherein the device comprises:

an entrance aperture to allow the ion beam to enter the device;

an exit aperture to allow the ion beam to exit the device;

a first set of electrodes disposed above an ion beam path, wherein the first set of electrodes comprises:

a first entrance-end electrode positioned closest, of the first set of electrodes, to the entrance aperture; and

a first exit-end electrode positioned closest, of the first set of electrodes, to the exit aperture, wherein the first entrance-end electrode is biased to within 5% of an electric potential to which the first exit-end electrode is biased; and

a second set of electrodes disposed below the ion beam path, wherein the second set of electrodes comprises:

a second entrance-end electrode positioned closest, of the second set of electrodes, to the entrance aperture; and

a second exit-end electrode positioned closest, of the second set of electrodes, to the exit aperture, wherein the second entrance-end electrode is biased to within 5% of an electric potential to which the second exit-end electrode is biased, and

wherein the first set of electrodes comprises a different number of electrodes than the second set of electrodes.

2 . The device of claim 1 , wherein the first set of electrodes are biased to electric potentials that are less negative than electric potentials to which the second set of electrodes are biased.

3 . The device of claim 1 , wherein:

a plurality of electrodes of the first set of electrodes are biased such that electric potentials of the plurality of electrodes of the first set of electrodes differ by at least 5%, and

the second set of electrodes are biased such that electric potentials of the second set of electrodes differ by at most 5%.

4 . The device of claim 1 , wherein one or more electrodes of the first set of electrodes and the second set of electrodes are biased to electric potentials between −2 kV and −15 kV.

5 . The device of claim 1 , wherein the first entrance-end electrode is electrically coupled to the first exit-end electrode, and the second entrance-end electrode is electrically coupled to the second exit-end electrode.

6 . The device of claim 1 , wherein the electric potential distribution across the first set of electrodes, from the first entrance-end electrode to the first exit-end electrode, is symmetric.

7 . The device of claim 1 , wherein the electric potential distribution across the second set of electrodes, from the second entrance-end electrode to the second exit-end electrode, is symmetric.

8 . The device of claim 1 , wherein the first set of electrodes comprises a greater number of electrodes than the second set of electrodes.

9 . The device of claim 1 , wherein the first set of electrodes comprises 3-7 electrodes and the second set of electrodes comprises 1-5 electrodes.

10 . The device of claim 1 , wherein the first set of electrodes comprises 5 electrodes and the second set of electrodes comprises 3 electrodes.

11 . The device of claim 1 , wherein the ion beam has a maximum energy of 5 keV.

12 . The device of claim 1 , wherein a central ray trajectory of the ion beam is deflected at a vertical angle of between 30 degrees and 90 degrees.

13 . The device of claim 1 , wherein a central ray trajectory of the ion beam is deflected at a vertical angle of 35 degrees.

14 . The device of claim 1 , wherein biasing the first set of electrodes and the second set of electrodes produces at least one effect on the ion beam selected from a group consisting of: parallelizing the ion beam, focusing the ion beam, and increasing a divergence of the ion beam.

15 . The device of claim 1 , wherein the device further comprises an insulator configured to electrically isolate an electrode of the first set of electrodes and an electrode of the second set of electrodes.

16 . The device of claim 1 , wherein one or more electrodes of the first set of electrodes, one or more electrodes of the second set of electrodes, or both, each comprise a circular cross section, wherein a diameter of the circular cross section is between 8 mm and 24 mm.

17 . The device of claim 1 , wherein the device further comprises one or more piston vacuum seals configured to hermetically seal one or more electrodes of the first set of electrodes, one or more electrodes of the second set of electrodes, or both.

18 . The device of claim 1 , wherein one or more electrodes of the first set of electrodes, one or more electrodes of the second set of electrodes, or both, comprise graphite and aluminum.

19 . The device of claim 1 , wherein one or more electrodes of the first set of electrodes, one or more electrodes of the second set of electrodes, or both, comprise a cylindrical graphite component, wherein the cylindrical graphite component is mated at a first end to a first cylindrical aluminum component and the cylindrical graphite component is mated at a second end to a second cylindrical aluminum component.

20 . The device of claim 1 , wherein one or more electrodes of the first set of electrodes or the second set of electrodes each comprise one or more wires disposed circumferentially about a central axis of a respective electrode of the one or more electrodes of the first set of electrodes or the second set of electrodes.

21 . The device of claim 20 , wherein the one or more wires comprise 4-12 wires.

22 . The device of claim 1 , wherein the first set of electrodes comprises a plurality of wires disposed above the ion beam path, wherein the electric potential difference between a given wire of the plurality of wires and a closest nearby wire of the plurality of wires does not exceed 200 V.

23 . The device of claim 1 , wherein the second set of electrodes comprises a plurality of wires disposed below the ion beam path, wherein the electric potential difference between a given wire of the plurality of wires and a closest nearby wire of the plurality of wires does not exceed 200 V.

24 . A method for electrostatic deflection of an ion beam, wherein the method comprises:

biasing a first set of electrodes disposed above an ion beam path, the first set of electrodes comprising a first entrance-end electrode positioned closest to an entrance aperture and a first exit-end electrode positioned closest to an exit aperture, such that electric potentials of the first entrance-end electrode and the first exit-end electrode differ by at most 5%; and

biasing a second set of electrodes disposed below the ion beam path, the second set of electrodes comprising a second entrance-end electrode positioned closest to the entrance aperture and a second exit-end electrode positioned closest to the exit aperture, such that electric potentials of the second entrance-end electrode and the second exit-end electrode differ by at most 5%,

wherein the first set of electrodes comprises a different number of electrodes than the second set of electrodes.

25 . The method of claim 24 , wherein:

biasing the first set of electrodes comprises biasing a plurality of electrodes of the first set of electrodes such that electric potentials of the plurality of electrodes of the first set of electrodes differ by at least 5%; and

biasing the second set of electrodes comprises biasing the second set of electrodes such that electric potentials of the second set of electrodes differ by at most 5%.

26 . The method of claim 24 , wherein biasing the first set of electrodes produces an electric potential distribution across the first set of electrodes, from the first entrance-end electrode to the first exit-end electrode, that is symmetric.

27 . The method of claim 24 , wherein biasing the second set of electrodes produces an electric potential distribution across the second set of electrodes, from the second entrance-end electrode to the second exit-end electrode, that is symmetric.