US3369142A - Device for generating a strong electronic beam from a plasma emitting cathode - Google Patents

Device for generating a strong electronic beam from a plasma emitting cathode Download PDF

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Publication number
US3369142A
US3369142A US541678A US54167866A US3369142A US 3369142 A US3369142 A US 3369142A US 541678 A US541678 A US 541678A US 54167866 A US54167866 A US 54167866A US 3369142 A US3369142 A US 3369142A
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US
United States
Prior art keywords
cathode
anode
electronic beam
generating
plasma
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
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US541678A
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English (en)
Inventor
Jacobsen Clas
Breitholtz Bo
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ABB Norden Holding AB
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ASEA AB
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Publication date
Application filed by ASEA AB filed Critical ASEA AB
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Publication of US3369142A publication Critical patent/US3369142A/en
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J3/00—Details of electron-optical or ion-optical arrangements or of ion traps common to two or more basic types of discharge tubes or lamps
    • H01J3/02—Electron guns
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
    • H01J37/02—Details
    • H01J37/04—Arrangements of electrodes and associated parts for generating or controlling the discharge, e.g. electron-optical arrangement or ion-optical arrangement
    • H01J37/06—Electron sources; Electron guns
    • H01J37/077—Electron guns using discharge in gases or vapours as electron sources

Definitions

  • a device for generating a strong electronic beam has a vacuum vessel; a cathode is arranged in the vessel.
  • An anode means comprises an annular acceleration anode and a collector anode.
  • the anode means may be arranged either inside or outside the vessel.
  • the cathode is surrounded by insulating material except for that surface turned away from the anode means.
  • An auxiliary anode is arranged in the vicinity of the cathode to start a plasma-emitting cathode spot on the uninsulated cathode surface.
  • the cathode and the auxiliary anode are provided with condensation screens of insulating material.
  • Heated cathodes In electronic valves and similar apparatus a heated cathode is usually used as the electronic source. Heated cathodes have however relatively low current density and are therefore not suitable when high current density is desired in the electronic beam.
  • a mercury cathode may be used as the electronic source. Ions and neutral gas atoms are also emitted from the cathode spot on such a cathode, which ions and atoms are thrown out in straight paths in all directions away from the cathode. The ions however return relatively quickly to the cathode, but the neutral atoms which are not influenced by the field in the arc continue and at a relatively great distance from the cathode may be ionised by electrons, which means that ions may occur practically anywhere between the anode and the cathode.
  • the present invention relates to a device for generating such a strong and pure electronic beam between a cathode arranged in a vacuum and an anode.
  • the invention is characterised in that the cathode is surrounded by insulating material except on a surface turned from the anode and that the plasma which expands from a cathode spot generated on said surface acts as the electronic source in the device.
  • the pure and high energetic electronic beam obtained can be used for many different purposes, such as welding, melting of metals in vacuum in order to obtain as far as possible gas-free metals and alloys, etc.
  • a cathode 2, a catch anode 3, an acceleration anode 4 and an auxiliary anode 5 are arranged in a vacuum container 1.
  • the cathode is surrounded by an insulating layer 6 of for example ceramic material. Only the upper surface 7 is free from the coating and on this surface is situated the ion and electron emitting cathode spot 8.
  • the auxiliary anode 5 is arranged immediately above the surface 7 "ice of the cathode and is raisable and lowerable through a wall of the container 1.
  • the cathode and the auxiliary anode are connected to an auxiliary voltage source 9.
  • a screen 10 is inserted between the cathode and the auxiliary anode in order to prevent a current in the auxiliary circuit.
  • condensation screen 11 On the auxiliary anode a condensation screen 11 is fixed by means of an insulating intermediate layer 12 and also the cahtode is provided with such a condensation screen which in the figure is denoted by 13 and is fixed at the insulating layer 6 surrounding the cathode.
  • the purpose of the condensation screens is to catch the neutral atoms which are emitted from the cathode spot and to prevent them from being transferred to the walls of the container.
  • the acceleration anode 4 is placed between the cathode and the catch anode.
  • the field in the acceleration anode is to be shaped so that the greatest possible part of the electronic current passes straight through the anode and reaches the catch anode.
  • a longitudinal magnetic field can be connected in.
  • the discharge is started by lowering the auxiliary anode until it makes contact with the cathode surface 7 and then raising it so that an arc occurs between the two electrodes.
  • the cathode spot 8 appears. Electrons, ions and neutral metal atoms are emitted from the cathode spot and these form a plasma over the cathode.
  • the ions and the neutral metal gas atoms can only move in straight paths and this is the reason why the plasma only exists above the straight line AA in the figure.
  • the electrons on the other hand can be influenced by the field from the main voltage source 14 and the potential of these can be chosen to be high if it is desirable to have a high are voltage drop and obtain a beam of high-energy electrons against the catch anode 3.
  • the electronic beam becomes very strong, since a cathode spot is used as the electronic source and the area of the cathode spot is to a great extent unlimited. What sets an upper limit for the electronic current is that at cur-rent strengths of several tens of kA the properties of the plasma above the cathode are determined by collision between the particles of the plasma, and neutral metal atoms are spread to the area below the line AA.
  • a high ohmic control electrode can be arranged on the cathode surface.
  • a third possibility is to start the discharge by means of a focus laser beam directed against the cathode.
  • the current source 9 can be disconnected as soon as the cathode spot has been created and the discharge stabilised.
  • the cathode must be manufactured of an extremely gas-free material in order that the quantity of neutral gas which is released during the fusing of the cathode will be as small as possible.
  • the cathode material can be solid or liquid metal, such as copper or mercury.
  • the catch anode can be arranged outside the container and the electronic beam can be taken out through a window arranged in the wall of the container between the acceleration anode and the catch anode. rIt is also possible to arrange both the acceleration anode and the catch anode outside the vacuum container.
  • a device for generating a strong electronic beam comprising anode means and a cathode, at least said cathode being arranged in a vacuum vessel, insulating material covering said cathode laterally and on the side facing said anode means, the surface of said cathode turned away from said anode means being uninsulated, whereby plasma which expands from a cathode spot generated on said surface constitutes an electronic source in the device, an auxiliary anode means in the vicinity of said cathode for starting a plasma emission, and a condensation screen of insulating material between said cathode and said auxiliary anode means.
  • auxiliary anode means and said cathode being provided with metallic 0ondensation screens, said condensation screens being insulated from said auxiliary anode means and said cathode.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Electron Sources, Ion Sources (AREA)
  • Manufacture Of Electron Tubes, Discharge Lamp Vessels, Lead-In Wires, And The Like (AREA)
US541678A 1965-04-12 1966-04-11 Device for generating a strong electronic beam from a plasma emitting cathode Expired - Lifetime US3369142A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
SE4719/65A SE321533B (enrdf_load_stackoverflow) 1965-04-12 1965-04-12

Publications (1)

Publication Number Publication Date
US3369142A true US3369142A (en) 1968-02-13

Family

ID=20264824

Family Applications (1)

Application Number Title Priority Date Filing Date
US541678A Expired - Lifetime US3369142A (en) 1965-04-12 1966-04-11 Device for generating a strong electronic beam from a plasma emitting cathode

Country Status (5)

Country Link
US (1) US3369142A (enrdf_load_stackoverflow)
CH (1) CH437547A (enrdf_load_stackoverflow)
DE (1) DE1539639B1 (enrdf_load_stackoverflow)
GB (1) GB1136144A (enrdf_load_stackoverflow)
SE (1) SE321533B (enrdf_load_stackoverflow)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113369661A (zh) * 2021-06-30 2021-09-10 中国航发动力股份有限公司 一种电子束焊接接头的保温工艺方法
CN116884827A (zh) * 2023-09-06 2023-10-13 艾瑞森表面技术（苏州）股份有限公司 真空等离子装置及加工方法

Families Citing this family (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2153140B (en) * 1983-12-20 1988-08-03 English Electric Valve Co Ltd Apparatus for forming electron beams
EP0146383B1 (en) * 1983-12-20 1992-08-26 Eev Limited Apparatus for forming electron beams
GB2190786A (en) * 1986-05-21 1987-11-25 Oxford Appl Res Ltd Liquid metal field emission electron source
DE3817897A1 (de) * 1988-01-06 1989-07-20 Jupiter Toy Co Die erzeugung und handhabung von ladungsgebilden hoher ladungsdichte
CA1330827C (en) * 1988-01-06 1994-07-19 Jupiter Toy Company Production and manipulation of high charge density
US5054046A (en) * 1988-01-06 1991-10-01 Jupiter Toy Company Method of and apparatus for production and manipulation of high density charge
US5153901A (en) * 1988-01-06 1992-10-06 Jupiter Toy Company Production and manipulation of charged particles
US5123039A (en) * 1988-01-06 1992-06-16 Jupiter Toy Company Energy conversion using high charge density
US5018180A (en) * 1988-05-03 1991-05-21 Jupiter Toy Company Energy conversion using high charge density
DE102009005620B4 (de) * 2009-01-22 2010-12-30 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. Verfahren und Anordnung zur Erzeugung eines Elektronenstrahls

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1929124A (en) * 1924-03-01 1933-10-03 Raytheon Inc Space current device
US2686275A (en) * 1951-03-31 1954-08-10 Rca Corp Art of storing or delaying the transmission of electrical signals
US2805365A (en) * 1954-01-06 1957-09-03 North American Phillips Compan Gas-filled amplifying tube
US2937300A (en) * 1957-12-26 1960-05-17 Rca Corp High density electron source

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1107838B (de) * 1957-06-20 1961-05-31 Licentia Gmbh Verfahren zur Extraktion von Ionen aus Gasentladungen
US2937390A (en) * 1957-12-27 1960-05-24 Ibm Loose toner pick-up device
FR1281964A (fr) * 1960-11-18 1962-01-19 Csf Nouvelle cathode à grand pouvoir émissif
FR1385711A (fr) * 1962-12-27 1965-01-15 Thomson Houston Comp Francaise Perfectionnements aux dispositifs à faisceaux électroniques

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1929124A (en) * 1924-03-01 1933-10-03 Raytheon Inc Space current device
US2686275A (en) * 1951-03-31 1954-08-10 Rca Corp Art of storing or delaying the transmission of electrical signals
US2805365A (en) * 1954-01-06 1957-09-03 North American Phillips Compan Gas-filled amplifying tube
US2937300A (en) * 1957-12-26 1960-05-17 Rca Corp High density electron source

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113369661A (zh) * 2021-06-30 2021-09-10 中国航发动力股份有限公司 一种电子束焊接接头的保温工艺方法
CN116884827A (zh) * 2023-09-06 2023-10-13 艾瑞森表面技术（苏州）股份有限公司 真空等离子装置及加工方法
CN116884827B (zh) * 2023-09-06 2023-12-05 艾瑞森表面技术（苏州）股份有限公司 真空等离子装置及加工方法

Also Published As

Publication number Publication date
GB1136144A (en) 1968-12-11
DE1539639B1 (de) 1969-10-02
CH437547A (de) 1967-06-15
SE321533B (enrdf_load_stackoverflow) 1970-03-09

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