Method and apparatus for generating ion beams
AssigneeAtomic Energy of Canada Limited
InventorMurray R. Shubaly
Life of this patent
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Abstract
In an ion beam source, the plasma is contained near the extraction front by a cup-shaped magnetic field for improved stability and uniformity. The intermediate electrode has a profiled electron beam aperture having a first narrowest section, a second slightly wider section, and the third, known, conical section. The anode electrode or anode insert has a very narrow entrance aperture followed by outwardly flared, longer, section.
Claims15
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.
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.
Dependencies are inferred from the claim text.