| 摘要 |
The invention is a unique and substantive improvement in ion source assemblies which is able to produce a ribbon-shaped ion beam having an arbitrarily chosen breadth dimension which is at least ten times greater [and often more than thirty times greater] than its thickness dimension, the breadth and thickness dimensions of the beam being normal (i.e., perpendicular) to the Z-axis direction of travel for the ion beam. In all its embodiments, the improved ion source will comprise not less than two discrete component parts: (i) A closed, solid wall, prism-shaped arc discharge chamber having limited width and depth dimensions, and which concurrently has an arbitrarily chosen and predetermined length dimension which can be as small as 80 millimeters and alternatively exceed 3,000 millimeters in size; and (ii) A primary electron trap assembly which comprises at least an adjacently located magnetic field generating yoke subassembly able to provide a discernible quadrupole magnetic field internally within a confined cavity volume existing within the measurable dimensions of the arc discharge chamber walls. |
| 主权项 |
1. In an ion beam source able to produce a ribbon-shaped ion beam having a measurable breadth dimension which is at least ten times greater than its thickness dimension, the breadth and thickness dimensions of the produced beam being normal to the Z-axis direction of travel for the beam, and wherein the ion beam source includes
(i) a closed arc discharge chamber including a discrete solid front wall which presents at least one exit aperture for ion beam egress, a discrete solid back wall, at least two laterally positioned and oppositely situated solid adjoining sidewalls, two discrete solid and oppositely placed contiguous endwalls, and an internal cavity of determinable volume and configuration, wherein the arc discharge chamber presents a predetermined width dimension which extends along the Y-axis, a set front-to-hack dimension which extends along the Z-axis, and an arbitrarily chosen fixed length dimension which extends along the X-axis and can vary in its measurable size from about 80 mm to about 3,000 mm, (ii) at least one thermionic cathode disposed within said internal cavity volume of said arc discharge chamber, each cathode terminal being able to emit a stream of moving primary electrons on-demand, (iii) a controlled orifice for introducing a gaseous substance into the internal cavity volume of the arc discharge chamber, (iv) at least one extraction electrode located externally to the exit aperture in the front wall of the arc discharge chamber, and (v) a remotely positioned source of electrical power having both a positive terminal and a negative terminal;
the substantive structural improvement of: an operative primary electron trap assembly able to generate and install at least one discernible quadrupole magnetic field on-demand within the internal cavity volume of the arc discharge chamber, wherein said installed quadrupole magnetic field primary electron trap assembly causes
(α) a redirection of travel pathways for the moving primary electrons emitted by the cathode terminal in a direction away from the internal peripheral regions and marginal edges of the cavity volume near the two adjoining sidewalls and the back wall of the arc discharge chamber,(β) a redirecting of travel movements for the primary electrons towards the central spatial zone then existing in the approximate middle of the confined cavity volume of the arc discharge chamber, and(δ) a distribution of the redirected primary electrons uniformly at the approximate middle of the confined cavity space over the length dimension distance of the arc discharge chamber, andwherein said primary electron trap assembly uses combined electric and magnetic fields of which no significant component is directed in the X-axis direction,andwherein said primary electron trap assembly comprises(a) at least one identifiable rod-shaped anode disposed upon the inner face surface of one laterally positioned adjoining sidewall of the arc chamber and extending over the length dimension of the adjoining sidewall in the X-axis direction within the cavity volume of the arc discharge chamber, said rod-shaped anode being immersed within and encompassed by said installed quadrupole magnetic field of high strength within the cavity volume such that the lines of magnetic flux curve over and around each disposed rod-shaped anode, said curved magnetic flux lines being effective to block primary electrons moving within the cavity volume from reaching each disposed rod-shaped anode,(b) a magnetic field generating yoke subassembly lying at a preset distance adjacent to and surrounding the exterior faces and perimeter of at least three discrete three walls of the arc discharge chamber, said magnetic field generating yoke subassembly comprising a open yoke framework upon which at least three discrete magnetic pole constructs of alternating polarity lie disposed azimuthally about the X-axis and extend over the length dimension of the arc discharge chamber, said polarity-alternating multiple pole constructs collectively generating and installing a discernible quadrupole magnetic field within the dimensional confines of the internal cavity volume of the arc discharge chamber,wherein the field strength of said installed quadrupole magnetic field is weaker, but not a zero value, along the internal face surface of the front wall than at the internal face surfaces of the two oppositely situated adjoining sidewalls and back wall of the arc chamber, andwherein the strength of said quadrupole magnetic field falls to an effective zero value at a spatial location which exists forward of the cavity midline along a central plane aligned with the X-axis and lies medially over the exit aperture in the front wall of the arc chamber,(c) a thermionic cathode which is spatially located at the internal face surface of an endwall of the arc discharge chamber such that the primary electrons emitted by the cathode surround and engage the null value axis of effectively zero magnetic field strength then existing approximately at the cavity volume midline along a central plane aligned with the X-axis and extending medially adjacent to the exit aperture in the front wall of the arc chamber, and(d) an electrical connection between said spatially located thermionic cathode and the arc chamber which causes the potential of said located cathode to have a small positive value with respect to the potential of the arc discharge chamber. |
