EP3853879A1 - Canon à électrons - Google Patents

Canon à électrons

Info

Publication number
EP3853879A1
EP3853879A1 EP19769112.4A EP19769112A EP3853879A1 EP 3853879 A1 EP3853879 A1 EP 3853879A1 EP 19769112 A EP19769112 A EP 19769112A EP 3853879 A1 EP3853879 A1 EP 3853879A1
Authority
EP
European Patent Office
Prior art keywords
cathode
electron gun
wehnelt cylinder
holder
gun according
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.)
Pending
Application number
EP19769112.4A
Other languages
German (de)
English (en)
Inventor
Christof Dietrich
Norbert FESTL
Harald Seidel
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.)
Hitachi Rail GTS Deutschland GmbH
Original Assignee
Hitachi Rail GTS Deutschland GmbH
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 Hitachi Rail GTS Deutschland GmbH filed Critical Hitachi Rail GTS Deutschland GmbH
Publication of EP3853879A1 publication Critical patent/EP3853879A1/fr
Pending legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J1/00—Details of electrodes, of magnetic control means, of screens, or of the mounting or spacing thereof, common to two or more basic types of discharge tubes or lamps
    • H01J1/02—Main electrodes
    • H01J1/13—Solid thermionic cathodes
    • H01J1/20—Cathodes heated indirectly by an electric current; Cathodes heated by electron or ion bombardment
    • H01J1/26—Supports for the emissive material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J3/00—Details of electron-optical or ion-optical arrangements common to two or more basic types of discharge tubes or lamps
    • H01J3/02—Electron guns
    • H01J3/027—Construction of the gun or parts thereof
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J1/00—Details of electrodes, of magnetic control means, of screens, or of the mounting or spacing thereof, common to two or more basic types of discharge tubes or lamps
    • H01J1/02—Main electrodes
    • H01J1/13—Solid thermionic cathodes
    • H01J1/15—Cathodes heated directly by an electric current
    • H01J1/18—Supports; Vibration-damping arrangements
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J1/00—Details of electrodes, of magnetic control means, of screens, or of the mounting or spacing thereof, common to two or more basic types of discharge tubes or lamps
    • H01J1/02—Main electrodes
    • H01J1/13—Solid thermionic cathodes
    • H01J1/20—Cathodes heated indirectly by an electric current; Cathodes heated by electron or ion bombardment
    • H01J1/28—Dispenser-type cathodes, e.g. L-cathode
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J1/00—Details of electrodes, of magnetic control means, of screens, or of the mounting or spacing thereof, common to two or more basic types of discharge tubes or lamps
    • H01J1/88—Mounting, supporting, spacing, or insulating of electrodes or of electrode assemblies
    • H01J1/94—Mountings for individual electrodes
    • 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
    • H01J23/04—Cathodes
    • 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
    • H01J23/07—Electron or ion guns producing a hollow cylindrical beam
    • 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
    • H01J23/08—Focusing arrangements, e.g. for concentrating stream of electrons, for preventing spreading of stream
    • H01J23/083—Electrostatic focusing arrangements
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J25/00—Transit-time tubes, e.g. klystrons, travelling-wave tubes, magnetrons
    • H01J25/34—Travelling-wave tubes; Tubes in which a travelling wave is simulated at spaced gaps
    • H01J25/36—Tubes in which an electron stream interacts with a wave travelling along a delay line or equivalent sequence of impedance elements, and without magnet system producing an H-field crossing the E-field
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J25/00—Transit-time tubes, e.g. klystrons, travelling-wave tubes, magnetrons
    • H01J25/34—Travelling-wave tubes; Tubes in which a travelling wave is simulated at spaced gaps
    • H01J25/42—Tubes in which an electron stream interacts with a wave travelling along a delay line or equivalent sequence of impedance elements, and with a magnet system producing an H-field crossing the E-field
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J3/00—Details of electron-optical or ion-optical arrangements common to two or more basic types of discharge tubes or lamps
    • H01J3/14—Arrangements for focusing or reflecting ray or beam
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J35/00—X-ray tubes
    • H01J35/02—Details
    • H01J35/04—Electrodes ; Mutual position thereof; Constructional adaptations therefor
    • H01J35/06—Cathodes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J35/00—X-ray tubes
    • H01J35/02—Details
    • H01J35/04—Electrodes ; Mutual position thereof; Constructional adaptations therefor
    • H01J35/06—Cathodes
    • H01J35/066—Details of electron optical components, e.g. cathode cups
    • 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
    • H01J37/067—Replacing parts of guns; Mutual adjustment of electrodes

Definitions

  • the invention relates to an electron gun, in particular for
  • An electron gun is a component by means of which thermal electrons are first generated, then accelerated and within one
  • Beam path can be focused on a target.
  • the electrons are released from a cathode, to which energy is supplied in the form of heat.
  • the electrons released from the cathode are then subjected to a first focusing by a Wehnelt cylinder, in which the electrons are aligned with an anode, which is usually designed as a pinhole.
  • the electrons are accelerated between the anode, which has a positive electrical potential with respect to the cathode, and the cathode.
  • Known designs for electron guns are, in addition to a large number of other designs, for example the Rogowski electron gun or the Pierce electron gun.
  • a Wehnelt cylinder focuses electrons into a continuous electron beam. The focusing takes place between the mostly concave Wehnelt cylinder and the anode
  • the focus of the electron beam is of particular importance in the construction of electron guns.
  • Constructive parameters by means of which the focusing and the divergence of an electron beam can be influenced are the shape of the Wehnelt cylinder, the shape of the Anode, the shape of the cathode, the respective potential differences between the components and the design-related distances between the components.
  • An electron gun is known from US 2006/0091776 A1, in which a disk-shaped cathode is arranged within a hood-like holder on a heating element and a Wehnelt cylinder is arranged around the heating element and the cathode, the Wehnelt cylinder and the
  • FR 2 965 971 B1 proposes a support structure for improving the
  • the carrier housing is simultaneously formed as an anode.
  • a replaceable cathode is shown in US Pat. No. 3,478,244, the cathode being insulated within a housing and the Wehnelt cylinder likewise being insulated from the housing.
  • traveling wave tubes which are often used in space travel, the focus of the electron beam and thus the mutual alignment of the components of an electron gun and the component strength under load are of particular importance.
  • an electron gun which comprises a cathode having a cathode holder and a cathode body and a Wehnelt cylinder, the cathode holder receiving the cathode body and the Wehnelt cylinder being suitable for free electrons which come out of the can emerge in the direction of the Wehnelt cylinder, bundle them into an electron beam and the Wehnelt cylinder is arranged at least in sections along a first inner surface facing the cathode holder in a form-fitting manner on an outer surface of the cathode holder and at least partially surrounds the cathode holder.
  • an electron gun is specified in which the cathode holder is the central component with the cathode body and also with the Wehnelt cylinder is connected, these components touching each other directly.
  • the Wehnelt cylinder is essentially hollow-cylindrical in shape and receives the cathode holder in its interior in a form-fitting manner, which can be either circular disk-shaped or cylindrical.
  • the cathode holder in turn takes up the cylindrical cathode body in its interior, which can also be hollow cylindrical.
  • the cathode body is frustoconical
  • the cathode holder is shaped with respect to its inner surface in such a way that it interacts positively with the frustoconical cooling body would be particularly advantageous.
  • the Wehnelt cylinder can have the shape of a truncated cone on its inner surface, so that a frustoconical structure of the cathode holder can engage in this inner surface of the Wehnelt cylinder. With such a configuration, the cathode body and the cathode holder could only escape in one direction.
  • cathode body is designed conically and engages in a corresponding inner surface of the cathode holder
  • the cathode body can then be introduced into the cathode holder from the direction in which thermal electrons are later emitted.
  • the Wehnelt cylinder is then additionally designed such that an area which projects in the direction of the central axis of the components and which covers the cathode holder also projects at least partially over the cathode body, the cathode body is trapped and cannot be wise vibrations fall out. Since the cathode holder, the cathode body and the Wehnelt cylinder interlock positively with one another, these components are firmly aligned with one another with respect to their central axis.
  • the components of the electron gun according to the invention are already shaped such that the electron beam can be focused easily and without further processing steps.
  • the Wehnelt cylinder is provided with an inner surface facing the electrons emerging from the cathode body, to which potential surfaces are formed which bundle and focus the electrons.
  • the area of the Wehnelt cylinder facing the beam axis of the electrons is typically conical in shape toward the cathode body.
  • the cross section of the Wehnelt cylinder can therefore be approximately trapezoidal, semicircular or parabolic in the area facing the beam axis.
  • the Wehnelt cylinder is at least partially electrically conductively connected to the outer surface of the cathode holder along the first inner surface, and the cathode holder and the Wehnelt cylinder have the same electrical potential.
  • Wehnelt cylinders and cathode holders therefore have the same electrical potential.
  • This electrical potential will usually be slightly negative with respect to the cathode body, so that the exit of electrons from the cathode body is preferred.
  • a thermal insulator can nevertheless be inserted between the Wehnelt cylinder and the cathode holder.
  • heat from the cathode body can only be limited to the
  • Wehnelt cylinders are delivered.
  • the cathode body is heated during operation of the electron gun, so measures like this are necessary to control the heat flow.
  • thermal insulation is understood to mean that either a material has been introduced or a constructive precaution has been taken by means of which the corresponding area can be actively cooled.
  • the material should be selected so that it at least inhibits the phononic heat transfer.
  • active cooling there are slits along which a cooling fluid, such as air, can flow.
  • Compounds from the group of tellurides come into consideration as materials which inhibit the thermal heat flow, or at least the phononic part of the heat flow. For example, bismuth telluride inhibits heat transfer using phonons, but allows electrons to move, so that potential equalization can take place.
  • an electrical insulator is arranged between the cathode holder and the cathode body, and the cathode holder and the cathode body have an unequal electrical potential.
  • This electrical insulator ensures that when the electron gun is operated along the inner surfaces of the cathode holder, which face the cathode body, an electrical field is created which is oriented in such a way that electrons are displaced within the cathode body in the direction of its central axis. The consequence of this is that the number of electrons per unit time that emerge from the cathode body in the area of the Wehnelt cylinder is increased.
  • the insulator requires a potential separation between the cathode body and the cathode holder.
  • the isolator between the cathode body and the cathode holder also separates the potential of the Wehnelt cylinder and cathode body.
  • thermal insulation in connection with a thermal insulation could also be provided, so that the heat flow between the cathode body and the cathode holder is reduced.
  • thermal insulation instead of an electrical insulator, so that the heat flow between the cathode body and the cathode holder is prevented as completely as possible.
  • the Wehnelt cylinder Due to the thermal separation of the cathode body and the cathode holder, the Wehnelt cylinder is also heated less, so that no or only a few thermal electrons are emitted from the Wehnelt cylinder.
  • thermal insulation to be introduced between the cathode holder and the Wehnelt cylinder, said insulation being arranged, for example, all around the cathode holder.
  • the cathode body is conductively connected at least in sections to an inner surface of the cathode holder and the cathode holder and the cathode body have the same electrical potential.
  • the cathode body, the cathode holder and the Wehnelt cylinder have the same electrical potential.
  • electrical insulation, which causes the Wehnelt cylinder to have a mostly more negative potential than the cathode is therefore not necessary and is therefore not provided.
  • thermal insulation can be provided between the Wehnelt cylinder and the cathode holder and / or between the cathode holder and the cathode body, so that no heat flow from the cathode body, which is usually heated by an external energy source, to the cathode - holder and there is no heat flow from the cathode holder to the Wehnelt cylinder.
  • Bismuth telluride or lead tellurium can be used as materials which offer good electrical conductivity but also good thermal insulation. Instead of insulation based on material properties, active cooling could also take place, for example by contacting a heat sink.
  • the electron gun is provided at least in regions with a non-emitting coating, this non-emitting coating having a greater work of triggering for the emission of electrons than the cathode body.
  • Thermal electrons can leave a solid-state composite if they have been supplied with sufficient energy in the form of heat. This is desirable in the case of a cathode body of an electron gun. In other areas, however, free electrons emerging from the metal composite are mostly undesirable. In order to avoid these electrons, which are referred to as parasitic interference electrons, the corresponding region from which an exit is undesirable can be cooled. By cooling, the material in the area is kept below the temperature at which Electrons are emitted. Alternatively, however, a material can be applied to the areas from which the escape of thermal electrons is undesirable, which has a high work function and thus inhibits the escape of thermal electrons.
  • the cathode holder, the cathode body and the Wehnelt cylinder can be in thermal equilibrium, and thus, for example, the Wehnelt cylinder could have approximately the same temperature as the cathode body, is provided by a corresponding coating of the surfaces prevents electrons from being released from the coated area of the Wehnelt cylinder.
  • the Wehnelt cylinder is provided with the non-emitting coating on a second inner surface facing the electron beam.
  • this mostly concave second inner surface lies on a side of the electron gun facing an anode.
  • non-emitting means that the material and temperature-dependent release work for electrons is greater in the material from which the non-emitting coating is made than in the material of the cathode. de. Low trigger work for the cathode body and high trigger work for the other components of the electron gun are generally intended.
  • the escape of thermal electrons from the Wehnelt cylinder must be reduced or prevented by applying a non-emissive coating to parts of the Wehnelt cylinder.
  • this coating could be provided on further components of the electron gun or further components of a tube in which the electron gun is used as an electron source.
  • the collector of a traveling wave tube could be provided with the non-emitting layer at least in some areas.
  • the non-emissive coating comprises hafnium as a component.
  • Hafnium has a high release work for electrons with the usual operating parameters of an electron gun.
  • a coating with hafnium or an alloy containing hafnium thus increases the release work in the coated areas, so that fewer electrons or no electrons are released from these areas.
  • the Wehnelt cylinder is made in two parts, an inner Wehnelt cylinder being surrounded by a hollow cylindrical outer Wehnelt cylinder.
  • the outer Wehnelt cylinder can advantageously be used as a jet shield to reduce heat radiation from the cathode.
  • the Wehnelt cylinder and the cathode holder are formed in one piece.
  • the connected component consisting of the Wehnelt cylinder and the cathode holder thus represents an essentially radially symmetrical component which could be manufactured simply and inexpensively using a CNC milling process.
  • this connected component is made from a material which has a high release work for electrons and is heat-resistant.
  • the cathode holder is designed as a hollow cylinder, the inside diameter being dimensioned such that the cathode body can be received in a form-fitting manner in the cathode holder.
  • the cathode body is often designed as a porous body and could have a carrier in which the material is inserted like a disc. The carrier would then engage in the cathode holder. In the case of the embodiment with an insulation introduced between the cathode holder or the cathode body, this is also hollow-cylindrical in accordance with the shape of the cathode holder and connects the cathode holder and the cathode body in a force-locking manner.
  • the cathode holder has on its outer surface a surface that is circumferential to the cathode holder. radially extending step formed at least in sections, the Wehnelt cylinder resting on this step.
  • a step is provided for the simple and firm connection of the Wehnelt cylinder and cathode holder, on which the Wehnelt cylinder rests in the assembled state.
  • a carrier device of a tube in which the electron gun is used can correspond to the step.
  • the electron gun can be easily inserted into a tube and is held in the tube by a support device.
  • a further carrier device can run in the direction of the beam axis, by means of which, for example, one or more anodes are held.
  • the cathode body is made of a porous material which is suitable for emitting free electrons when energy is supplied in the form of heat.
  • the work function essentially depends on material-specific properties. Since it is desired to exit thermal electrons from the cathode, the cathode is made from a low work function material. Since the current of the thermal electrons is proportional to the area from which the electrons are emitted, the material is made porous, ie with a large area.
  • the electron gun comprises a pickling device which is suitable for supplying energy to the cathode body in the form of heat, the pickling device being on one of the
  • Wehnelt cylinder opposite side of the cathode body is arranged and is optionally arranged within the cathode holder. Accordingly, a heating element is provided within the cathode holder, from which heat can be given off to the cathode body, so that the thermal electrons can overcome the work function of the cathode body.
  • the heating device is at least electrically insulating from the cathode body, so that the current flow heating the heating element does not also heat the cathode holder or even the Wehnelt cylinder. It is also expedient for the heating device to be designed thermally with respect to the cathode holder in which it can be arranged.
  • the heating device can also be designed as a rod which engages at least partially in an electrically insulated manner in the cathode body.
  • the heating device can be arranged within a cylindrical body which corresponds to the inner surface of the cathode holder. It is also possible for the heating element to be assigned to the tube in which the electron gun is used and to be arranged, for example, on a carrier device for the electron gun. According to this, the electron gun would be held in the tube and aligned, among other things, via the heating device.
  • the electron gun comprises an anode arranged along its beam axis, the anode having an electrical potential which is positive with respect to the cathode and is electrically insulated from the Wehnelt cylinder, the cathode body and the cathode. Regardless of the potential that exists between the cathode body, the cathode holder and the Wehnelt cylinder, this ensures that the cathode has a negative electronic potential compared to the anode. Electrons that emerge from the cathode body due to heating are thus accelerated in the direction of the anode.
  • the anode is convex and, in terms of its shape, corresponding to the Wehnelt cylinder.
  • the anode can be arranged on the Wehnelt cylinder or, for example, on the step of the cathode body by means of an insulated or insulating carrier.
  • the anode it is also possible to use several anodes arranged one behind the other in the course of the beam axis.
  • the anode can be aligned with respect to the Wehnelt cylinder, the cathode and the beam axis using an adjusting means.
  • Such an adjustment means could, for example, be one or more screws running radially with respect to the beam axis, via which the anode is connected to an insulating or insulated support structure.
  • the anode with its central axis, that is, with its hole formed in the middle could be aligned precisely with the electron beam.
  • the components can be aligned with one another in such a way that the electron beam is focused on a target.
  • the electron gun can be focused before it is installed in a tube.
  • this has the advantage that focusing outside the tube can still be carried out easily because the individual components can still be accessed, on the other hand, the complexity when assembling a tube is reduced.
  • traveling wave tubes for example, focusing the electron beam is one of the most complex steps in assembling the tube. Assembling traveling wave tubes is made significantly easier with electron guns that have already been focused in advance.
  • the use of an electron gun with the aforementioned features within a tube is specified as an electron source.
  • Such a tube could be an X-ray tube, for example.
  • a traveling wave tube typically comprises a delay line, a collector and an electron source, which is designed as one of the above-mentioned electron guns.
  • the Wehnelt cylinder is neither thermally or electrically insulated from the cathode, but also no electrons can escape from it, because at least in certain areas it is provided with a non-emissive coating .
  • a particularly simple construction of an electron gun is thus possible without the need to provide further insulators, spacers or cooling elements.
  • 1 shows an electron gun according to the invention in a sectional representation
  • 2 shows an embodiment of the electron gun according to the invention in a sectional view
  • FIG. 3 shows a further embodiment of the electron gun according to the invention in a sectional view
  • Fig. 4 shows a further embodiment of the invention
  • FIG. 6 shows a traveling wave tube with an electron gun according to the invention in a sectional view
  • FIG. 7 shows an X-ray tube with an electron gun according to the invention in a sectional view.
  • an electron gun EK which has a Wehnelt cylinder WZ and a cathode holder KH and a cathode body KK having cathode KA.
  • the cathode holder KH receives the cathode body KK along its inner surface Kl.
  • the Wehnelt cylinder WZ in turn receives the cathode holder KH along its outer inner surface WI1 along its outer surface KA.
  • FIG. 2 shows an embodiment of the electron gun in which the Wehnelt cylinder WZ touches the cathode holder KH directly, but the cathode holder KH is separated from the cathode body KK by means of an insulation IS.
  • the potential of the Wehnelt cylinder WZ and the cathode holder KH with respect to the cathode body KK could be positive or negative, usually a negative potential of the Wehnelt cylinder WZ, in which the Wehnelt cylinder WZ compared to the Cathode body KK has a negative potential, is preferred.
  • the electron gun EK shown in FIG. 2 also includes a stage ST on which the Wehnelt cylinder WZ is supported. On its side facing away from the Wehnelt cylinder WZ, the cathode holder KH is also provided with an internal cutout AU, which can engage when using the electron gun EK within a tube arrangement, for example a support structure or a fleece element.
  • the front side of the Wehnelt cylinder WZ shown in FIG. 2 is inclined significantly more towards a direction of an electron beam in the direction towards the anode, so that the Wehnelt cylinder WZ is shorter along this direction and thus has less mass .
  • Wehnelt cylinder WZ ' is provided, which along the direction of an electron Beam encloses the inner Wehnelt cylinder WZ and the cathode holder KH in the form of a hollow cylinder.
  • the outer Wehnelt cylinder WZ ' also serves to shield the heat radiation emitted by the cathode.
  • inner Wehnelt cylinders WZ and outer Wehnelt cylinders WZ ' one could also speak of a two-part Wehnelt cylinder.
  • a heating element HE is shown, from which energy in the form of heat can be given to the cathode body KK.
  • the heating element HE is arranged inside the cathode holder KH and is thermally and electrically separated from it via a spacer AH.
  • the electron gun shown in FIG. 3 is designed such that the Wehnelt cylinder WZ and the cathode holder KK are provided as a common, one-piece component.
  • the boundaries between the Wehnelt cylinder WZ and the cathode holder KH, as would be present in the design as separate components, are shown in FIG. 3 with a broken line.
  • the electron gun in FIG. 3 has a step ST to which the electron gun can be held within a tube.
  • An anode AN is arranged on a side of the electron gun EK opposite the heating device HE. Between the anode AN and the concave Wehnelt cylinder WZ, half-shell-shaped potential surfaces PF run as far as possible. Along these potential surfaces PF, thermal electrons released from the cathode body KK are focused in the direction of a pinhole provided in the anode AN.
  • the anode AN itself has a positive potential with respect to the cathode KA, so that the free electrons emerging from the cathode body KK are accelerated toward the anode AN.
  • the non-emissive coating NS shown in FIG. 4 is arranged, for example, along the second inner surface WI2 of the Wehnelt cylinder WZ. This non-emitting coating NS does not release any thermal electrons called interference emissions from this area. Furthermore, a non-emissive coating NS is also provided on the outer surface WA of the Wehnelt cylinder WZ.
  • the meat device HE shown in FIG. 4 is arranged in a support structure TK of a tube, not shown.
  • the support structure TK which can accommodate the electron gun EK within a tube arrangement, for example, rests on the step ST, as does the Wehnelt cylinder.
  • the non-emitting coating NS can be provided at any point or in any area of the electron gun EK, with a coating being particularly useful in the area of the electron beam.
  • the coating can be vapor-deposited, for example.
  • 5 shows different potential constellations between the Wehnelt cylinder WZ, the cathode holder KH, the cathode body KK and the anode AN.
  • 5A shows a constellation in which the cathode body KK has a low negative electrical potential P2 compared to the Wehnelt cylinder WZ and the cathode holder KH.
  • the higher negative potential P1 is applied to the Wehnelt cylinder WZ and the cathode holder KH.
  • the anode AN has an electrical potential P3 which is negative with respect to the zero point 0, but more positive with respect to the other potentials.
  • FIG. 5A is particularly advantageous because the more negative potential of the cathode holder KH and Wehnelt cylinder WZ forces electrons into the inner region of the cathode body KK, so that in this region the electron density increases and the Trigger work is reduced or the number of electrodes released per unit of time increases. The reverse of this is shown in Fig. 5B.
  • the potential distribution shown in FIG. 5B again provides a more positive potential P3 for the anode AN, but the lower negative potential P2 is present at the Wehnelt cylinder WZ and the cathode holder KH.
  • the cathode body KK on the other hand, has the higher negative electrical potential.
  • the result of this arrangement is that the electrons are more concentrated within the edge region of the cathode body KK facing the cathode holder KH.
  • an emission takes place predominantly along this edge region.
  • 5C shows an embodiment in which the Wehnelt cylinder WZ, the cathode holder KH and the cathode body KK are not insulated from one another. There, the Wehnelt cylinder WZ, the cathode holder KH and the cathode body KK all have the higher negative electrical potential P1.
  • the anode AN again has the more positive potential P3.
  • FIG. 5C all components except the anode AN have the same higher negative electrical potential P1, these components could at least be thermally insulated from one another. It should be noted in Fig. 5 that it it is a non-scaled axis from which only the polarity of an electrical potential and thus also the direction of an electrical field between individual components can be taken. The absolute amount of individual potential differences cannot be found in FIG. 5.
  • FIG. 6 shows a traveling field tube arrangement WR in which an electron gun EK according to the invention is connected to the tube RO via a support structure TK.
  • the anode AN of the electron gun EK is also connected via a support structure PK.
  • the support structure TK of the anode AN rests on the stage ST of the electron gun EK.
  • the TK support structures are each electrically insulated.
  • a helical delay line FIX follows, into which electrical signals are fed from an input IN to an output OFF.
  • Around the delay line FIX is a magnetic focusing device ME, which forms the electron beam within the delay line FIX.
  • the collector KO follows in the path of the electron beam ES, in which the electrons of the electron beam ES are collected. Since the electron gun EK with its anode AN, its Wehnelt cylinder WZ, its cathode holder KH and the cathode body KK and the filler element HE was already focused before being inserted into the tube RO, this step no longer had to be carried out when assembling the traveling wave tube WR . The provision of an already pre-focused electron gun thus saves time in the firing of traveling wave tube arrangements WR.
  • FIG. 7 Another tube, namely an X-ray tube, is shown in FIG. A preconfigured electron gun EK, the components of which were already coordinated with one another with regard to the focusing of the electron beam, was also installed in FIG. 7.
  • the electron beam ES from the Electron gun EK goes out, is passed to an anti-cathode UK with an anode AN behind it, the electrons being braked so strongly when the electrons of the electron beam ES strike the anti-cathode UK that this X-ray radiation RS in a direction specified by the anti-cathode submit.
  • the electron gun as described in this application, can be used in all tubes that require an electron source in the form of an electron gun.

Landscapes

  • Electron Sources, Ion Sources (AREA)
  • Microwave Tubes (AREA)

Abstract

L'invention concerne un canon à électrons qui comprend une cathode, comportant un support de cathode et un corps de cathode, et un cylindre de Wehnelt. Le support de cathode reçoit le corps de cathode et le cylindre de Wehnelt est adapté pour concentrer des électrons libres qui peuvent sortir du corps de cathode en direction du cylindre de Wehnelt, en un faisceau d'électrons, et le cylindre de Wehnelt est disposé au moins par endroits le long d'une première surface intérieure, faisant face au support de cathode, par complémentarité de formes sur une surface extérieure du support de cathode et entoure au moins partiellement le support de cathode.
EP19769112.4A 2018-09-20 2019-09-11 Canon à électrons Pending EP3853879A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE102018123100.8A DE102018123100A1 (de) 2018-09-20 2018-09-20 Elektronenkanone
PCT/EP2019/074183 WO2020058053A1 (fr) 2018-09-20 2019-09-11 Canon à électrons

Publications (1)

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EP3853879A1 true EP3853879A1 (fr) 2021-07-28

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US (1) US11990307B2 (fr)
EP (1) EP3853879A1 (fr)
DE (1) DE102018123100A1 (fr)
WO (1) WO2020058053A1 (fr)

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Publication number Priority date Publication date Assignee Title
US11380509B2 (en) * 2020-01-28 2022-07-05 GE Precision Healthcare LLC Systems and methods for controlling thermal conduction in x-ray tube cathodes
CN120149130B (zh) * 2025-02-27 2025-11-25 电子科技大学 一种应用于回旋管的非绝热平面发射电子枪

Citations (4)

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US3154711A (en) * 1961-06-19 1964-10-27 Gen Electric Electron beam focusing by means of contact differences of potential
US6771737B2 (en) * 2001-07-12 2004-08-03 Medtronic Ave, Inc. X-ray catheter with miniature emitter and focusing cup
US20060091776A1 (en) * 2004-10-28 2006-05-04 Nec Microwave Tube, Ltd. Electron gun
FR2965971A1 (fr) * 2010-10-06 2012-04-13 Thales Sa Tube a ondes progressives avec alignement ameliore du canon avec la structure hyperfrequences du tube et procede de fabrication d'un tel tube

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FR759676A (fr) 1932-09-01 1934-02-07 Fernseh Ag Dispositif de montage d'une cathode incandescente dans les tubes à rayons cathodiques
CH452067A (de) 1965-12-14 1968-05-31 Steigerwald Strahltech Elektronenstrahl-Erzeugungsvorrichtung
US3610988A (en) * 1968-12-12 1971-10-05 Telefunken Patent Cathode arrangement and cathode-ray tube having such a cathode arrangement
DE3407434A1 (de) * 1984-02-29 1985-08-29 Siemens AG, 1000 Berlin und 8000 München Strahlerzeugersystem fuer elektronenroehren, insbesondere wanderfeldroehren
CA1286769C (fr) 1988-01-07 1991-07-23 Hans Joachim Kolpin Canon electronique
US6115453A (en) * 1997-08-20 2000-09-05 Siemens Aktiengesellschaft Direct-Heated flats emitter for emitting an electron beam
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US3154711A (en) * 1961-06-19 1964-10-27 Gen Electric Electron beam focusing by means of contact differences of potential
US6771737B2 (en) * 2001-07-12 2004-08-03 Medtronic Ave, Inc. X-ray catheter with miniature emitter and focusing cup
US20060091776A1 (en) * 2004-10-28 2006-05-04 Nec Microwave Tube, Ltd. Electron gun
FR2965971A1 (fr) * 2010-10-06 2012-04-13 Thales Sa Tube a ondes progressives avec alignement ameliore du canon avec la structure hyperfrequences du tube et procede de fabrication d'un tel tube

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See also references of WO2020058053A1 *

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US20210350995A1 (en) 2021-11-11
US11990307B2 (en) 2024-05-21
DE102018123100A1 (de) 2020-03-26
WO2020058053A1 (fr) 2020-03-26

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