Method and apparatus for generating ion beams

Claim 2

An ion beam source apperatus of the type comprising cathode means in a cathode chamber for generating an electron beam, means for collimating said electron beam, aperture means in said cathode chamber for admitting the collimated electron beam into an ionizing chamber for containing an ion plasma, anode means at one end of said ionizing chamber adjacent said aperture means, and ion beam extraction means at the opposite end of said ionizing chamber, CHARACTERIZED IN THAT said aperture means is a bore in said cathode chamber having a smaller cross-section adjacent said cathode means, said smaller cross-section being sufficient for electron beam passage therethrough, and said aperture means including a predetermined length thereof having a predetermined uniform cross-section larger than said smaller cross-section.

Claim 3

The apparatus as defined in claim 1, said aperture means in said cathode chamber comprising first, second and third sections; the first section, adjacent the cathode means, having the smallest cross-section; and the second, intermediate, section having an intermediate cross-section between the smallest cross-section and a larger cross-section of the third section.

Claim 4

The apparatus as defined in claim 2, said first and second sections being cylindrical.

Claim 5

The apparatus as defined in claim 3, said third section being conical.

Claim 9

An ion beam source comprising a hot cathode for generating electrons and being positioned in a cathode chamber to which a gas is supplied by a primary gas supply means, a generally cylindrical, partly conical, intermediate electrode made of a magnetic material defining the cathode chamber and having an electrode canal therein at the apex of the conical part for admitting the electrons into a generally cylindrical reflex arc chamber via an intermediate region, the reflex arc chamber being axially aligned with but separated from the intermediate electrode and defining the said intermediate region therebetween, the said reflex arc chamber having the intermediate electrode at one end, a plasma aperture plate at the other end and first and second anodes at locations between said ends, the first anode being provided with a hole therein which is axially aligned with the electrode canal and through which the electrons are admitted into the reflex arc chamber, secondary gas supply means for supplying a gas to be ionized into the reflex arc chamber, the plasma aperture plate having one or more apertures therein through which the ionized gas emerges from the reflex arc chamber and extraction means positioned near the plasma aperture plate comprising accelerating and decelerating electrodes to extract and accelerate ions emerging from the reflex arc chamber, wherein the electrode canal is in a stepped configuration having a narrow uniform cross-section at one end nearest to the hot cathode followed by a larger uniform cross-section and ending in a concave opening at the other end facing the intermediate region, an intermediate electrode ring made of a non-magnetic material is located about and connected electrically to the intermediate electrode and there are further provide a compressor coil on the intermediate electrode to create an electron confining magnetic field in the reflex arc chamber and the intermediate region and power supply means for supplying electrical potentials to the cathode, the intermediate electrode, the first and second anodes and the plasma aperture plate so that the electrons admitted into the reflex arc chamber bounce back and forth between the intermediate electrode and the plasma aperture plate and, in so doing, ionize the gas in the reflex arc chamber by colliding therewith.

Claim 10

An ion beam source comprising a hot cathode for generating electrons and being positioned in a cathode chamber to which a gas is supplied by a primary gas supply means, a generally cylindrical, partly conical, intermediate electrode made of a magnetic material defining the cathode chamber and having an electrode canal therein at the apex of the conical part for admitting the electrons into a generally cylindrical reflex arc chamber via an intermediate region, the reflex arc chamber being axially aligned with but separated from the intermediate electrode and defining the said intermediate region therebetween, the said reflex arc chamber having the intermediate electrode at one end, a plasma aperture plate at the other end and first and second anodes at locations between said ends, the first anode being provided with a hole therein which is axially aligned with the electrode canal and through which the electrons are admitted into the reflex arc chamber, secondary gas supply means for supplying a gas to be ionized into the reflex arc chamber, the plasma aperture plate having one or more apertures therein through which the ionized gas emerges from the reflex arc chamber and extraction means positioned near the plasma aperture plate comprising accelerating and decelerating electrodes to extract and accelerate ions emerging from the reflex arc chamber, wherein the electrode canal is in a stepped configuration having a narrow uniform cross-section at one end nearest to the hot cathode followed by a larger uniform cross-section and ending in a concave opening at the other end facing the intermediate region, an intermediate electrode ring made of a non-magnetic material is located about and connected electrically to the intermediate electrode and there are further provide a compressor coil on the intermediate electrode to create an electron confining magnetic field in the reflex arc chamber and the intermediate region and power supply means for supplying electrical potentials to the cathode, the intermediate electrode, the first and second anodes and the plasma aperture plate so that the electrons admitted into the reflex arc chamber bounce back and forth between the intermediate electrode and the plasma aperture plate and, in so doing, ionize the gas in the reflex arc chamber by colliding therewith.

Claim 11

The ion beam source of claim 8 wherein a generally cylindrical anode insert made of a non-magnetic material is rotatably fitted in the hole of the first anode, the anode insert having an inside bore which is flared to match the electron confining magnetic field created by the compressor coil.

Claim 12

The ion beam source of claim 9, wherein the first anode has passage means connected to the secondary gas supply means and the anode insert has a flange to secure the anode insert against the first anode, the said flange having one radial port milled in one surface thereof and another radial port in the other surface so that either port can be aligned with the passage means by rotating the anode insert.

Claim 13

The ion beam source of claim 10, comprising further means for closing the secondary gas supply means so that a gas can be introduced through the primary gas supply means to the cathode chamber and then to the reflex arc chamber to be ionized by the electrons.

Claim 14

The ion beam source of claim 11, wherein the gas to be introduced through the primary gas supply means is a gas selected from a group consisting of argon, xenon, nitrogen, hydrogen and neon.

Claim 15

The ion beam source of claim 10, wherein the gas to be supplied by the primary gas supply means is a gas selected from a group consisting of argon, xenon, nitrogen, hydrogen and neon, and the gas to be supplied by the secondary gas supply means is a gas selected from a group consisting of argon, xenon, nitrogen, hydrogen, neon, phosphine, arsine, boron trifluoride and oxygen.

Claim 16

The ion beam source of claims 8, 9 or 10, wherein the canal said narrow uniform cross-section is cylindrical and has a diameter of 5.5 mm and said larger uniform cross-section is cylindrical and has a diameter of 6.0 mm.

Claim 17

The ion beam source of claims 11, 12 or 13, wherein said narrow uniform cross-section is cylindrical and has a diameter of 5.5 mm and said larger uniform cross-section is cylindrical and has a diameter of 6.0 mm.