# US 6,404,115 B1 · Particle beam emitting assembly > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 6,404,115 B1 - Document ID: US6404115B1 - Status: Granted - Kind: B1 - Application number: 09/508,914 - Filed: 2000-06-13 - Granted: 2002-06-11 - Earliest claimed: 1997-09-24 - Assignees: The Welding Institute - Inventors: Allan Sanderson - Web page: https://patentgrep.com/patent/US6404115B1 ## CPC - H01J 37/075: Electron guns using thermionic emission from cathodes heated by particle bombardment or by irradiation, e.g. by laser - H01J 37/063: Geometrical arrangement of electrodes for beam-forming - H01J 37/065: Construction of guns or parts thereof (H01J37/067 - H01J37/077 take precedence) - H01J 37/301: Arrangements enabling beams to pass between regions of different pressure - H01J 2237/3104: Welding - H01J: ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS (spark-gaps H01T; electric arc lamps H05B31/00; particle accelerators H05H) ## Abstract A charged particle emitting assembly comprises an emitter member (5) for emitting charged particles of one polarity. A tubular shield electrode (6) circumferentially surrounds the emitter member and is held in use at the same polarity as the charged particles. A tubular accelerating electrode (7) is positioned substantially coaxially with the shield electrode (6) and is held in use at the opposite polarity to the shield electrode. The arrangement is such that charged particles from the emitter member (5) initially spread laterally outwardly and then are focused into a beam which passes through the tubular accelerating electrode (7). ## Claims ### Claim 1 A charged particle emitting assembly comprising an emitter member for emitting charged particles of one polarity; a tubular shield electrode circumferentially surrounding the emitter member and held in use at the same polarity as the charged particles; and a tubular accelerating electrode positioned substantially coaxially with the shield electrode and held in use at the opposite polarity to the shield electrode, the arrangement being such that charged particles from the emitter member initially spread laterally outwardly and then are focused into a beam which passes through the tubular accelerating electrode. ### Claim 2 (depends on 1) An assembly according to claim 1, wherein the electrodes are arranged to generate an electrostatic field which initially causes divergence of the charged particle beam in a direction from the emitter member towards the tubular electrode. ### Claim 3 (depends on 2) An assembly according to claim 2, wherein the emitter is mounted to a central portion of the shield electrode, projecting from a base of the shield. ### Claim 4 (depends on 3) An assembly according to claim 3, wherein the projecting, central portion tapers outwardly towards the base of the shield electrode. ### Claim 5 (depends on 1) An assembly according to claim 1, further comprising means for causing the emitter to emit the charged particles. ### Claim 6 (depends on 5) An assembly according to claim 5, wherein the means for causing the emitter to emit charged particles comprises a source of second charged particles arranged to bombard the emitter. ### Claim 7 (depends on 6) An assembly according to claim 6, wherein the charged particles emitted by the source comprise electrons. ### Claim 8 (depends on 1) An assembly according to claim 1, wherein the charged particles emitted by the emitter comprise electrons. ### Claim 9 (depends on 6) An assembly according to claim 6, wherein the source of second charged particles includes an inductively heated auxiliary emitter. ### Claim 10 (depends on 1) An assembly according to claim 1, wherein the shield electrode has a substantially cylindrical side. ### Claim 11 (depends on 1) An assembly according to claim 1, wherein the tubular electrode terminates adjacent a plane defined by the edge of the shield electrode. ### Claim 12 (depends on 1) An assembly according to claim 1, wherein the emitter comprises an emitter member mounted in an aperture of a support member to which it is electrically connected, the emitter member having a lower work function than the support member whereby at a working temperature, the emitter member emits charged particles from an exposed surface. ### Claim 13 A charged particle emitter comprising an emitter member mounted in an aperture of a support member to which it is electrically connected, the emitter member having a lower work function than the support member whereby at a working temperature, the emitter member emits charged particles from an exposed surface characterised in that the exposed surface of the emitter member is substantially flush with or set back from an outwardly facing surface of the support member surrounding the aperture. ### Claim 14 (depends on 13) An emitter according to claim 13, wherein the emitter member is a close fit in the aperture of the support member. ### Claim 15 (depends on 13) An emitter according to claim 13, wherein part of the support member and part of the emitter member are correspondingly tapered. ### Claim 16 (depends on 15) An emitter according to claim 15, wherein the part of the support member and emitter member taper inwardly towards the exposed surface of the emitter member. ### Claim 17 (depends on 13) An emitter according to claim 13, wherein the emitter member is secured to the support member by a clip which engages each member. ### Claim 18 (depends on 17) An emitter according to claim 17, wherein the clip is received in a groove in the support member. ### Claim 19 (depends on 13) An emitter according to claim 13, wherein the exposed surface of the emitter member and the outwardly facing surface of the support member define a common plane. ### Claim 20 (depends on 19) An emitter according to claim 19, wherein the exposed surface of the emitter member and the outwardly facing surface of the support member define one of a convex, conical, concave or re-entrant form. ### Claim 21 (depends on 13) An emitter according to claim 13, wherein the support member includes a cone shaped section. ### Claim 22 (depends on 13) An emitter according to claim 13, wherein the emitter member emits electrons when heated to the working temperature. ### Claim 23 (depends on 13) An emitter according to claim 13, wherein the emitter member comprises lanthanum hexaboride. ### Claim 24 (depends on 13) An emitter according to claim 13, wherein the support member comprises tantalum. ### Claim 25 (depends on 12) An assembly according to at least claim 12, wherein the emitter comprises a charged particle emitter comprising an emitter member mounted in an aperture of a support member to which it is electrically connected, the emitter member having a lower work function than the support member whereby at a working temperature, the emitter member emits charged particles from an exposed surface characterised in that the exposed surface of the emitter member is substantially flush with or set back from an outwardly facing surface of the support member surrounding the aperture. ### Claim 26 (depends on 1) Welding apparatus including a charged particle emitting assembly according to claim 1; a workpiece support for supporting a workpiece exposed to the charged particle beam; and means for causing relative movement between the charged particle beam and the workpiece support. ### Claim 27 A charged particle beam column assembly for mounting to an evacuated charged particle beam source chamber, the assembly having a sequence of controlled pressure chambers, each having inlet and outlet apertures through which a charged particle beam can pass and an evacuation port for connection to a pump to enable the pressure in the chamber to be controlled, whereby the pressure in successive chambers increases in use characterised in that an evacuation port is connected to a downstream chamber via a conduit which extends within the assembly past at least one upstream chamber. ### Claim 28 (depends on 27) An assembly according to claim 27, wherein the chambers are defined by nested tubes, each conduit being formed by the tubular wall of a tube defining the chamber to which the conduit is connected and the tubular wall of the next upstream chamber. ### Claim 29 (depends on 28) An assembly according to claim 28, wherein the nested tubes are substantially coaxial. ### Claim 30 (depends on 27) An assembly according to claim 27, wherein the chambers are defined by a set of tubular sections located within an outer tube, each tubular section having a radially outwardly facing opening, the radially outwardly facing opening of each chamber being circumferentially offset from the radially outwardly facing openings of all the other chambers; and a set of axially extending dividing walls positioned between the tubular sections and the outer tube to form the respective conduits, each conduit connecting the radially outwardly facing opening of a chamber with a corresponding evacuation port. ### Claim 31 (depends on 30) An assembly according to claim 30, wherein the tubular sections have substantially the same diameter. ### Claim 32 (depends on 28) An assembly according to claim 28, wherein the nested tubes or the tubular sections are substantially cylindrical. ### Claim 33 (depends on 27) An assembly according to claim 27, wherein the inlet aperture of one chamber is defined by the outlet aperture of the next adjacent upstream chamber. ### Claim 34 (depends on 27) An assembly according to claim 27, wherein the inlet and outlet apertures define a rectilinear path for the beam. ### Claim 35 (depends on 27) A charged particle beam assembly comprising an evacuated charged particle beam source chamber coupled to an assembly according to claim 27. ### Claim 36 (depends on 35) An assembly according to claim 35, wherein the pressure of the chamber furthest from the charged particle beam source chamber is held below atmospheric pressure. ### Claim 37 (depends on 35) A charged particle beam assembly according to claim 35, wherein the evacuated charged particle beam source chamber includes a source comprising a charged particle emitting assembly comprising an emitter member for emitting charged particles of one polarity; a tubular shield electrode circumferentially surrounding the emitter member and held in use at the same polarity as the charged particles; and a tubular accelerating electrode positioned substantially coaxially with the shield electrode and held in use at the opposite polarity to the shield electrode, the arrangement being such that charged particles from the emitter member initially spread laterally outwardly and then are focused into a beam which passes through the tubular accelerating electrode.