US3588600A - Nonuniform crossed field electron gun for producing a stable electron beam orbit - Google Patents

Nonuniform crossed field electron gun for producing a stable electron beam orbit Download PDF

Info

Publication number
US3588600A
US3588600A US866202A US3588600DA US3588600A US 3588600 A US3588600 A US 3588600A US 866202 A US866202 A US 866202A US 3588600D A US3588600D A US 3588600DA US 3588600 A US3588600 A US 3588600A
Authority
US
United States
Prior art keywords
anode
cathode
tube
electrons
electrode
Prior art date
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
Application number
US866202A
Other languages
English (en)
Inventor
Norihiko Nakayama
Minoru Tanaka
Eizo Miyauchi
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Fujitsu Ltd
Original Assignee
Fujitsu Ltd
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Fujitsu Ltd filed Critical Fujitsu Ltd
Application granted granted Critical
Publication of US3588600A publication Critical patent/US3588600A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J23/00—Details of transit-time tubes of the types covered by group H01J25/00
    • H01J23/02—Electrodes; Magnetic control means; Screens
    • H01J23/06—Electron or ion guns
    • H01J23/075—Magnetron injection guns

Definitions

  • a nonuniform crossed field electron gun has a I long thin anode parallel to the axis of the tube and a cathode spaced from the anode by a constant interval and opposite the anode.
  • An electrode of dihedral configuration has a vertex with an elongated aperture formed therein in the center area of the vertex. The cathode is positioned in the aperture and the electrode opens toward the anode.
  • An electric field B(y) is produced in the area between the anode and the electrode to provide movement of electrons in axial direction of the tube.
  • a magnetic field B( y) is produced which has a strength which varies as a function of the distance y from the cathode to the anode in a direction transverse to that of the electric field and the axis of the tube.
  • Our invention relates to an electron gun More particularly, the invention relates to a nonuniform crossed field electron gun.
  • the electron gun of our invention is particularly adapted for use in electron tubes such as cathode-ray tubes and travellingwave tubes.
  • an electron tube utilizing an electron beam such as, for example, a cathode-ray tube, a travelling-wave tube or a velocity modulation tube
  • the obtaining of a large beam current presents a considerable problem.
  • An increase of the beam current in a cathode-ray tube permits the reduction of high voltage for acceleration and contributes to increased brightness.
  • Increased beam current in a travelling-wave tube or a velocity modulation tube contributes to the output power.
  • Electron guns utilized to produce electron beams in conventional electron tubes generally comprise a cathode having an electron radiating surface directed at right angles to the axis of the tube and a plurality of electrostatic electron lenses positioned coaxially with the cathode.
  • the area of the cathode is limited by the radius of the tube.
  • it becomes very difficult to focus the emitted electrons and it is therefore impossible to provide a beam of a current large enough for present purposes.
  • an electron beam is produced in the direction of the axis of the tube from a plate-shaped cathode having an electron radiating surface extending in the direction of the axis of the tube due to the utilization of acrossed field.
  • An electron gun of this type is described in an article by G. S. Kino, entitled A Design Method For Crossed Field Guns, IRE Transactions, Volume 7, July, 1960, pages 179 to 185.
  • the electron gun described in the Kino article is commonly referred to as the Kino gun.
  • the Kino gun may provide a slightly larger beam current than the electron gun of the firstmentioned type.
  • the Kino gun has a considerably complicated mechanism and design. It is therefore extremely difficult to produce a stable electron beam with the Kino gun. Furthermore, it is practically impossible to focus the electron beam thinly in the Kino gun.
  • This electron gun is a special crossed field electron gun and is based on the concept that when an electric field and a magnetic field which cross each other act on a space in which there is a movement of electrons, and the distribution of the magnetic field is made nonuniform so that the distribution is the same as the 2 for l betatron, a stable orbit of electrons is produced in such space.
  • This electron gun is different in principle from the Kino gun and the first-mentioned type of electron gun, since it utilizes a magnetic field of nonuniform distribution.
  • Our previously invented electron gun has the advantage that there is no limit in theory to the area of the cathode and the radiated electrons may be produced in a stable orbit. This electron gun is described in further detail with reference to FIG. 1.
  • the electron gun previously invented by us has the disadvantage that it is difficult to focus the electron beam in the lateral direction.
  • the cross section of the electron beam thus becomes bandshaped or oval, since said electron beam may be focused in the direction of the axis of the tube.
  • electron beams of such cross-sectional configuration may be effectively utilized with certain types of objects, they are unsuitable for electron tubes requiring thin beams such as, for example, cathode-ray tubes.
  • the principal object of the invention is to provide a new and improved nonuniform crossed field electron gun.
  • An object of the invention is to provide a nonuniform crossed field electron gun which focuses the electron beam in the lateral direction as well as in the direction of the axis of the tube.
  • An object of the invention is to provide a nonuniform crossed field electron gun which produces electron beams of large current.
  • An object of the invention is to provide a nonuniform crossed field electron gun which produces a thinly focused electron beam.
  • An object of the invention is to provide a nonuniform crossed field electron gun which functions with efficiency, effectiveness and reliability.
  • a nonuniform crossed field electron gun for a tube having an axis comprises a long thin anode parallel to the axis of the tube.
  • a cathode is spaced from the anode by a constant interval and opposite the anode.
  • An electrode of dihedral configuration has a vertex with an elongated aperture formed therein in the center area of the vertex.
  • the cathode is positioned in the aperture formed in the vertex of the electrode.
  • the electrode opens toward the anode.
  • Voltage means connected to the anode and the electrode provides different potentials to the anode and the e1ectrode to produce an electric field E( y) in the area between the anode and the electrode thereby providing movement of electrons in axial direction of the tube.
  • Magnetic means in operative proximity with the tube produces a magnetic field B(y) having a strength which varies as a function of the distance y from the cathode to the anode in a direction transverse to that of the electric field and the axis of the tube.
  • the electrode comprises nonmagnetic material and the magnetic means comprises a pair of spaced magnets in operative proximity with the tube in symmetrical positions relative to a plane through the axis of the tube and the longitudinal center of the cathode and in asymmetrical positions relative to any other plane through the axis of the tube.
  • the magnet is positioned in a manner whereby like poles of the magnet are opposite each other.
  • the electrode comprises a pair of thin plates joined to each other in dihedral configuration at an angle of substantially
  • the cathode is a direct heated-type cathode extending substantially parallel to the axis of the tube and substantially elongated and thin along its length
  • the cathode comprises a nickel ribbon.
  • the cathode and the vertex of the electrode are substantially parallel to the axis of the tube.
  • the cathode and the vertex of the electrode are oblique to the axis of the tube.
  • the anode is an elongated thin plate extending parallel to the axis of the tube and having a substantially cylindrical trough formed therein along its length and opening in the same direction as the electrode.
  • the centerline of the trough is the centerline of the anode arid is in a vertical plane through the vertex of the electrode.
  • FIG. 1 is a schematic diagram of the electron gun disclosed in our pending U.S. Pat. application, Ser. No. 703,513, now Pat. No. 3,492,531;
  • FIG. 2 is a schematic diagram illustrating electron focusing based on the principle of quadruple electrodes
  • FIG. 3 is a graphical presentation illustrating the potential distribution and the magnetic field distribution in the nonuni-form crossed field electron gun of the invention
  • FIG. 4 is a perspective schematic diagram of an embodiment of the nonuniform crossed field electron gun of the inention
  • FIG. is a sectional view taken along the lines v-V of FIG. 41-.
  • FIG. 6 is a schematic diagram, partly in axial section, of a modification of the embodiment of FIGS. 4 and 5.
  • a plate-shaped anode I is spaced from an electrode 2 and is positioned in opposition with said electrode.
  • a cathode 3 is provided in nearly the same-plane as the electrode 2.
  • the space between the anode 1 and the electrode 2 is such that the electrode structure may be regarded as equivalent to part of an annular space for movement of electrons in a betatron, which annular space has an infinitely enlarged radius.
  • the 2 for 1 rule of a betatron may be ordinarily expressed as Therefore, if the coordinate system of the space provided between the electrodes is determined as shown in FIG.
  • the electrode structure comprises the anode I to which a positive potential is applied, the electrode 2 positioned opposite said anode and the cathode 3 positioned in essentially the same plane as said electrode.
  • a magnetic field lB( y) to focus the electron beam produced by the electron gun of 1 FIG. l in the lateral direction.
  • the electrons radiated from the cathode 3 enter into the straight stable orbit 4, said electrons may be focused in the direction perpendicular to the surface of said cathode.
  • Such direction is the x direction shown in FIG. 1.
  • focusing cannot be provided in the lateral direction of the cathode, so that the cross-sectional configuration of the electron beam becomes band-shaped or oval.
  • the electron gun of our invention utilizes the concept of a stable orbit of electrons based on the 2 for 1 rule of the betatron.
  • the electron gun of the invention is superior to the electron guns of other types, since it produces electron beams -of large current.
  • the problem of focusing theelectron beam provided in the stable orbit in a lateral direction is solved in our invention by utilizing the principle of quadruple electrodes to provide electron focusing action.
  • a ribbon-shaped cathode is spaced from a long thin anode extending in the axial direction ofthe tube by a constant distance and is opposed to said anode.
  • an electrode is provided which is of dihedral configuration, or open V type configuration, opening toward the anode and accommodating the cathode along part ofits vertex.
  • An electric field of nonuniform distribution and a magnetic field of nonuniform distribution are provided incrossing relation with each other and are applied tothe space of movement of electrons between the anode and the dihedral electrode.
  • the electrons from the cathode pass through a single stable orbit determined by the crossed electric and magnetic fields and are derived in the direction of the axis of the tube as a thinly focused electron beam.
  • the electron gun of our invention is thus very effectively utilizable in cathode-ray tubes.
  • Equation (I) in order to provide a straight or linear stable orbit, it is necessary to provide to the space of movement of electrons a magnetic field of nonuniform distribution which satisfies the 2 for l rule of the betatron expressed by Equation (I). It is also necessary to provide an electric field which will produce a voltage of a magnitude or value suhsmnfiallv Pmml tn the critical vnltaoP and tn annlv perpendicular to the plane of the sheet of illustration and nonuniformly distributed in the y direction, and an electric field B(y) applied to the space of movement of electrons and perpendicularly crossing the magnetic field and nonuniforrnly distributed in the y direction.
  • the motion of the electrons radiated from the cathode 3 are ordinarily expressed as wherein e is the charge of the electrons, m is the mass of the electrons and t is the time.
  • the potential distribution V( Y) and the magnetic field distribution B(y) in the space of movement of electrons may generally be expressed as wherein E0 and P are constants which determine the electric field, b and c are constants which determine the magnetic field distribution, and d is the distance between the cathode 3 and the anode l.
  • Equations (4) and (6) The relation between the potential distribution and the magnetic field distribution, expressed by Equations (4) and (6), is illustrated in FIG. 3.
  • the abscissa represents the distance y from the cathode 3 toward the anode l and the ordinate represents the potential V and the magnetic field strength B.
  • the potential distribution curve is indicated as V( y) and the magnetic field distribution curve is indicated as B(y).
  • O is the position of the cathode 3
  • d is the position of the anode l
  • b the strength of the magnetic field at the position of the cathode
  • 0 the strength of the magnetic field at the position of the anode
  • Vd is the anode potential.
  • an electric field of nonuniform distribution IS utilized as the electric field in order to provide a stable orbit and a special electrode structure, based on the principle of quadruple electrodes, is utilized in order to focus electrons in the lateral direction under the control of the electric field.
  • the quadruple electrode construction is shown in FIG. 2.
  • two positive potential poles 6 and 7 are provided in coplanar position and two negative potential poles 8 and 9 are provided in coplanar position, the plane of one pair of poles intersecting the plane of the other pair of poles at right angles.
  • the positive potential poles 6 and 7 are positioned opposite each other and the negative potential poles 8 and 9 are positioned opposite each other.
  • the potential distribution is indicated by the lines 10.
  • the potential indication by lines 11 and 12 pass from intermediate positions between positive potential poles and negative potential poles through the axis between all the poles and become zero at such axis.
  • an electron beam 13 is provided along the axis in a direction perpendicular to the plane of illustration, said electron beam is focused so that it has a cross-sectional configuration, illustrated by the crosshatched lines 14, of an oblong elongated in one direction and compressed in the perpendicular direction.
  • FIGS. 4 and 5 illustrate a preferred embodiment of the electron gun of our invention.
  • an anode 15 is the equivalent of a positive potential pole of the quadruple electrode structure of FIG. 2.
  • An electrode 16,17 is positioned in correspondence with the zero potential lines 11 and 12 of the quadruple electrode structure of FIG. 2 and is provided as a dihedral configuration having a vertex with an elongated aperture formed therein in the center area of the vertex.
  • the electrode 16,17 opens toward the anode 15.
  • a cathode 18 is positioned in the aperture formed in the vertex of the electrode 16,17.
  • the angle of the dihedral electrode 16,17 is substantially 90. It is not, however, necessary to strictly regulate this angle.
  • the space of movement of electrons is enclosed by the anode 15 and the electrode 16,17. Therefore, in order to provide a nonuniform magnetic field in the space of movement of electrons, it is necessary that the electrode 16,17 comprise nonmagnetic material such as, for example, copper or stainless steel.
  • the cathode 18 is of direct heated-type and comprises a long thin nickel ribbon and an electron radiating material coated on the surface of said ribbon. The cathode 18 extends in a direction parallel to the axis of a tube 22, shown in broken lines, which supports the electron gun structure.
  • the anode 15 is an elongated thin plate extending parallel to the axis of the tube 22 and having a substantially semicylindrical trough formed therein along its length and opening in the same direction as the electrode 16,17.
  • the centerline of the trough is the centerline of the anode 15 and is in a vertical plane through the vertex of the electrode 16,17.
  • a suitable voltage source not shown in the FIGS. is connected from outside the tube 22 to the electrodes 16,17 in the electron gun structure, as well as to the anode 15 and the cathode 18. It is especially desirable to support one end of the cathode 18 with spring bias, so thatthermal expansion may be compensated for.
  • the nonuniform magnetic field may be provided, for example, by a pair of magnets 20 and 21, as shown in FIG. 5.
  • the magnets 20 and 21 are spaced'from each other and are in operative proximity with the tube 22 in symmetrical positions relative to a plane through the axis of said tube and the longitudinal center of the cathode 18.
  • the magnets 20 and 21 are in asymmetrical positions relative to any other plane through the axis of the tube 22..
  • Each of the magnets 20 and 21 has a curved pole face which corresponds with the wall of the tube 22.
  • the magnets 20 and Y 21 are asymmetrical relative to the axis of the tube 22 in a manner whereby like poles of said magnets are opposite each other.
  • Magnetic lines of force 23 in FIGS. 4 and 5 illustrate the condition of the magnetic field provided by the magnets 20 and 21 in the space of movement of electrons.
  • the magnetic field is provided in a distribution which is strong on the side of the cathode 18 and is gradually weakened as it approaches the anode 15. Needless to say, however, the magnetic field may also be provided in a distribution which increases as the anode 15 is approached, as far as Equations (7) and (8) are satisfied.
  • Equation (8) may be rewritten as Equation (9), in order to express the anode voltage Vd.
  • FIG. 6 illustrates a modification of the embodiment of FIGS. 4 and 5.
  • the cathode l8 and the vertex of the electrode 16', 17' extend obliquely with .or inclined to the axis of the tube 22.
  • the cathode ll8 and the vertex of the electrode 16,17 extend parallel to the axis of the tube 22. It has been confirmed by experiment that by positioning the cathode obliquely to the axis of the tube 22, the force of the electric field, as against the electrons, may be provided with a component in the axial or x direction. This results in a reduction of the suppression effect on electrons by the space charge. It is desirable to select the angle of inclination of the cathode 18' relative to the axis of the tube 22 as from 5 to 6.
  • FIG. 6 illustrates a first grid 24 for acceleration of electrons, a magnet 25 for prefocusing of electrons and a second grid 26.
  • the first grid 24 for the acceleration of the electrons has the same potential applied to it as that applied to the anode 15.
  • the first grid 24, the magnet 25 and the second grid 26 function as the principal electron lens.
  • a nonuniform crossed field electron gun for a tube having an axis said electron gun comprising a long thin anode parallel to the axis of the tube;
  • an electrode of dihedral configuration having a vertex with an elongated aperture formed therein in the center area of said vertex, said cathode being positioned in the aperture formed in the vertex of said electrode, said electrode opening toward said anode;
  • L is the position of the stable orbit of electrons between the cathode and anode
  • e is the charge of electrons
  • m is the mass of electrons
  • P is a constant

Landscapes

  • Microwave Tubes (AREA)
  • Particle Accelerators (AREA)
  • Electron Beam Exposure (AREA)
US866202A 1968-10-15 1969-10-14 Nonuniform crossed field electron gun for producing a stable electron beam orbit Expired - Lifetime US3588600A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP7517568 1968-10-15

Publications (1)

Publication Number Publication Date
US3588600A true US3588600A (en) 1971-06-28

Family

ID=13568589

Family Applications (1)

Application Number Title Priority Date Filing Date
US866202A Expired - Lifetime US3588600A (en) 1968-10-15 1969-10-14 Nonuniform crossed field electron gun for producing a stable electron beam orbit

Country Status (4)

Country Link
US (1) US3588600A (de)
DE (1) DE1950872B2 (de)
FR (1) FR2020745A1 (de)
GB (1) GB1232740A (de)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3932820A (en) * 1973-07-06 1976-01-13 The British Secretary of State for Defense Crossed field amplifiers
US4021697A (en) * 1975-12-10 1977-05-03 Warnecke Electron Tubes, Inc. Crossed-field amplifier
US4308486A (en) * 1979-11-27 1981-12-29 Rca Corporation Line cathode structure having recessed geometry
CN104735897A (zh) * 2015-03-30 2015-06-24 同方威视技术股份有限公司 电子帘加速器、接收极和电子加速方法

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3932820A (en) * 1973-07-06 1976-01-13 The British Secretary of State for Defense Crossed field amplifiers
US4021697A (en) * 1975-12-10 1977-05-03 Warnecke Electron Tubes, Inc. Crossed-field amplifier
US4308486A (en) * 1979-11-27 1981-12-29 Rca Corporation Line cathode structure having recessed geometry
CN104735897A (zh) * 2015-03-30 2015-06-24 同方威视技术股份有限公司 电子帘加速器、接收极和电子加速方法
CN104735897B (zh) * 2015-03-30 2017-08-25 同方威视技术股份有限公司 电子帘加速器、接收极和电子加速方法

Also Published As

Publication number Publication date
FR2020745A1 (de) 1970-07-17
DE1950872A1 (de) 1970-08-13
DE1950872B2 (de) 1972-03-30
GB1232740A (de) 1971-05-19

Similar Documents

Publication Publication Date Title
US2608668A (en) Magnetically focused electron gun
US2853641A (en) Electron beam and wave energy interaction device
US2707758A (en) Travelling wave tube
US3980919A (en) Rectangular beam laminar flow electron gun
US2464562A (en) Discharge tube
US3702951A (en) Electrostatic collector for charged particles
Bevc et al. On the design of the transition region of axisymmetric, magnetically focused beam valves
US3894261A (en) No-crossover electron gun
US3172004A (en) Depressed collector operation of electron beam device
US3588600A (en) Nonuniform crossed field electron gun for producing a stable electron beam orbit
GB2139413A (en) An electron gun
US3315110A (en) Shaped-field hollow beam electron gun having high beam perveance and high beam convergence ratio
US3148302A (en) Microwave amplifier tube with direct current field interaction means for the electron beam
US5955849A (en) Cold field emitters with thick focusing grids
GB1078832A (en) Electrostatic electron optical system
US3373310A (en) Cathode ray tube selective deflection amplifier using a quadrupole lens of critical length
US3217200A (en) Internal magnetic lens for electron beams
US2997615A (en) Brillouin flow gun
US2564743A (en) Charged particle beam forming apparatus
US3378718A (en) Crossed-field traveling wave electron reaction device employing cyclotron mode interaction
GB709842A (en) Improvements in apparatus comprising means for concentrating beams of charged particles
US3492531A (en) Non-uniform magnetic field type electron current generating device
US3226587A (en) Cathode ray tube and magnetic deflection means therefor
US3454806A (en) System for the production of a flat electron beam for a traveling wave tube with purely electrostatic focusing
US2996640A (en) Variable beam electron gun