US3459994A - Crossed-field discharge device and improved magnetic pole structures therefor - Google Patents

Crossed-field discharge device and improved magnetic pole structures therefor Download PDF

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US3459994A
US3459994A US584769A US3459994DA US3459994A US 3459994 A US3459994 A US 3459994A US 584769 A US584769 A US 584769A US 3459994D A US3459994D A US 3459994DA US 3459994 A US3459994 A US 3459994A
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anode
disposed
pole pieces
annular
extending
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James E Staats
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General Electric Co
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General Electric Co
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    • 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
    • H01J23/36—Coupling devices having distributed capacitance and inductance, structurally associated with the tube, for introducing or removing wave energy
    • H01J23/40—Coupling devices having distributed capacitance and inductance, structurally associated with the tube, for introducing or removing wave energy to or from the interaction circuit
    • H01J23/48—Coupling devices having distributed capacitance and inductance, structurally associated with the tube, for introducing or removing wave energy to or from the interaction circuit for linking interaction circuit with coaxial lines; Devices of the coupled helices type
    • 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
    • H01J23/10—Magnet systems for directing or deflecting the discharge along a desired path, e.g. a spiral path
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J25/00—Transit-time tubes, e.g. klystrons, travelling-wave tubes, magnetrons
    • H01J25/50—Magnetrons, i.e. tubes with a magnet system producing an H-field crossing the E-field
    • H01J25/52—Magnetrons, i.e. tubes with a magnet system producing an H-field crossing the E-field with an electron space having a shape that does not prevent any electron from moving completely around the cathode or guide electrode
    • H01J25/54—Magnetrons, i.e. tubes with a magnet system producing an H-field crossing the E-field with an electron space having a shape that does not prevent any electron from moving completely around the cathode or guide electrode having only one cavity or other resonator, e.g. neutrode tubes
    • H01J25/56—Magnetrons, i.e. tubes with a magnet system producing an H-field crossing the E-field with an electron space having a shape that does not prevent any electron from moving completely around the cathode or guide electrode having only one cavity or other resonator, e.g. neutrode tubes with interdigital arrangements of anodes, e.g. turbator tube

Definitions

  • FIGJ 236a 227 INVEN TOR JAMES E. STA/1T5 BY VWIQATTYS.
  • a crossed-field discharge device comprising an envelope enclosing an anode structure which defines an axially extending space, an electron emissive cathode structure disposed in the axially extending space and a pair of identical composite pole pieces disposed adjacent to the opposite ends of the anode structure, each composite pole piece including an inner annular pole piece disposed internally of the envelope and an outer annular pole piece disposed externally of the envelope in radial alignment with the inner pole piece, the outer diameter of the composite pole piece being from about 2.0 to about 2.5 times the axial gap between the internal pole pieces.
  • the present invention relates to an improved crossedfield discharge device and particularly to an improved magnetic pole structure therefor, and to microwave assem'blies incorporating the improved crossed-field discharge device therein.
  • a further object of the invention is to provide a microwave assembly incorporating therein the improved crossed-field discharge device of the present invention, the device also being provided with a plurality of radially extending cooling fins mounted on the envelope in good thermal contact therewith, a pair of annular field coils disposed with the axes thereof in alignment with the longitudinal axis of the interaction space and respectively arranged adjacent to the opposite ends of the device for establishing a unidirectional magnetic field therebetween, a
  • cooling fins a pair of outer sections disposed on opposite sides of the associated field coil and magnetically coupled to the end section and extending toward the device and terminating at points spaced outwardly and well away from the associated external pole piece, and side walls of non-magnetic material interconnecting the opposed pairs of the outer sections, the end sections and the outer sections and the side walls cooperating to provide a box-like structure open on two opposed sides thereof and defining a passage for cooling air passing therethrough and over the cooling fins and around the device to cool the same.
  • a still further object of the invention is to provide a microwave assembly of the type set forth wherein the cooling fins and the end sections have substantially rectangular peripheries and the outer sections are disposed on opposed sides of the rectangular end sections, the cooling fins being formed of copper and the side walls being formed of aluminum.
  • FIGURE 1 is a view in vertical section through a microwave assembly incorporating therein a crossed-field discharge device of the present invention, there being illustrated and associated with the device magnetic field coils therefor and the magnetic return structure and air duct housing therefor and the coupler and filter construction used therewith;
  • FIG. 2 is an enlarged view in vertical section through the crossed-field discharge device illustrated in FIG. 1;
  • FIG. 3 is a view in horizontal section through the assembly of FIG. 1 along the line 33 thereof;
  • the anode structure 101 is essentially annular in shape and is confined within the interior of the sleeve 102 (see FIGS. 2. and 5), the sleeve 102 being generally tubular and having a circular cross section at all points therealong, the outer surface 103 thereof being cylindrical.
  • the inner surface 104 of the sleeve 102 is also cylindrical in shape and has at each end thereof a recess to define upper and lower end Walls 102 and upper and lower side walls 106 of reduced thickness, the end walls 105 being essentially annular in shape and disposed parallel to each other and normal to the axis of the device 100 the side walls 106 being annular in shape and extending axially of the device 100.
  • the sleeve 1-02 and the fins 108 are formed of a metal having good thermal conductivity, the preferred material being copper, thereby to accommodate the conduction of heat from the device 100 outwardly therefrom and into the fins 108.
  • the shape of the fins 108 is substantially rectangular so that they fit within a box-like structure 200 disposed therearound, there preferably being provided means for passing a cooling fluid, such as a stream of air, through the box-like structure 200 and over the fins 108 to effect cooling thereof and a consequent removal of heat from the device 100 during the operation thereof.
  • each anode member 1 10 is generally annular in shape and includes a body portion 111 disposed at one end thereof (the upper end as viewed in FIG. 2), the body portion 111 having an outer end wall 112 at one end thereof connecting with an annular outer wall 113 having an outer diameter only slightly less than the inner diameter of the sleeve 102, and specifically the inner surface 104 thereof, whereby the anode member 110 can fit within the sleeve 102 and ultimately is connected thereto as by brazing.
  • the end of the body portion 111 opposite the end wall 112 is cut away or recessed to provide an annular inner Wall 114 extending therearound and concentric with the annular outer wall 113 but having a substantially smaller diameter, the walls 113 and 114 being joined by an annular end wall 115 disposed parallel to the outer end wall 112 and normal to the walls 113 and 114; the other end of the inner wall 114 connects with an inner end wall 116 that defines the other end of the body portion 111, the end wall 116 being disposed in a plane parallel to the end walls 112 and 115 and normal to the walls 113 and 114.
  • anode member 110 There is provided interiorly of the anode member 110 and extending the length of the body portion 111 a plurality of axially extending anode segments 117 that project radially inwardly into the axially extending space within the anode member 110 and providing therebetween a corresponding plurality of axially extending anode recesses 122, fifteen of the anode segments 11 7 and fifteen of the corresponding recesses 122 being provided in the anode member 110 as illustrated.
  • Each of the anode segments 117 has an axially extending inner surface 118 and a pair of outwardly directed side walls 119 on the opposite sides thereof, the circumferential extent of the inner surface 118 being substantially less than the radial extent of the associated side walls 119.
  • the anode member 110 further has thereon and integral therewith fifteen rods or vanes 125, each of the rods 125 being integral with and extending longitudinally from one of the anode segments 117. More specifically, the inner surface 118 of each of the anode segments 117 extends forwardly beyond the inner end wall 116 and substantially parallel to the axis of the anode member 110 and forms the inner surface of the associated rod 125. A portion of the side walls 119 on the anode segment 117 also extends forwardly beyond the inner end wall 116 to provide the radially extending sides of the associated rod 125, the inner surface 118 and the side walls 119 terminating at an end 126 disposed substantially normal to the axis of the anode member 110.
  • An outer surface 127 is provided for each of the rods 125, the outer surface 127 extending from the inner end wall 116 forwardly to the rod 126; more specifically, the inner end of the outer surface 127 joins the inner end wall 116 at a point spaced radially inwardly away from the adjacent outer walls 121 (see FIG. 4) and tapers inwardly toward the associated inner surface from the end wall 116 to the rod end 126.
  • the anode members 110 are also formed of a metal having good thermal conductivity, the preferred material being copper.
  • the sleeve 102 and the anode members 110 also must have good electrical conductivity, the copper providing the necessary good electrical conductivity as well as the good thermal conductivity.
  • one of the anode members 110 is disposed in the upper portion of the sleeve 102 with the body portion 111 thereof disposed upwardly and with the rods 125 thereof extending downwardly; the other one of the anode members 110 is disposed in the lower portion of the sleeve 102 with the body portion 111 thereof disposed downwardly and with the rods 125 thereof extending upwardly.
  • FIG. 2 and 5 one of the anode members 110 is disposed in the upper portion of the sleeve 102 with the body portion 111 thereof disposed upwardly and with the rods 125 thereof extending downwardly; the other one of the anode members 110 is disposed in the lower portion of the sleeve 102 with the body portion
  • the anode members 110 are rotated slightly with respect to each other so that the anode rods 125 on one of the anode members 110 are disposed in the center of the recesses 12 of the other one of the anode members 110, and conversely the anode rods 125 on the other one of the anode members 110 are disposed in the center of the recesses 122 of the one anode member 110.
  • the sleeve 102 and the anode members 110 also cooperate to provide an outer axially extending space 120, the space 120 being annular in shape and bounded on the outer portion by the inner wall 104 of the sleeve 102 and on the inner portion by the inner walls 114 and at the upper and lower ends by the end walls 115.
  • the interior of the anode members 110 form a second or inner axially extending space Within which is disposed the cathode structure 150, the space between the outer surface of the cathode structure 150 and the spaced facing surfaces 118 defining an annular axially extending interaction space 160.
  • the inner end walls 116 are spaced apart to provide therebetween a radially extending annular passage 123 interconnecting the outer space 120 at the mid-portion thereof to the inner axially extending space at the midportion thereof and to the interaction space 160 at the mid-portion thereof.
  • the cathode structure 150 is provided in the axially extending space defined by the anode members 110, the cathode structure 150 including a cylindrical metal wall 151 (see FIG. 4) arranged with the axis thereof disposed at the axis of the device 100, the wall 151 being formed of a heat resistant and electrically conducting metal, the preferred material of construction being nickel. Mounted on each end of the wall 151 is a cathode end 152, the cathode ends 152 being substantially identical in construction, whereby the same reference numerals have been applied to like parts of both.
  • the upper cathode end 152 it includes a substantially flat annular center plate 153 carrying on the outer edge thereof an axially directed annular inner flange 154 carrying on the inner end thereof an outwardly directed flat flange 155; the outer periphery of the flange 155 carries a mounting flange 156 thereon extending outwardly and disposed within the adjacent end of the wall 151 and suitably secured thereto as by welding.
  • the outer edge of the flange 156 carries a radially and outwardly extending shield flange 157 that extends radially outwardly beyond the wall 151 and overlies the adjacent end of the interaction space 160.
  • Each center plate 153 has a central opening 158 therein, the lower cathode end 152 carrying on the inner edge and surrounding the opening 158 therein a center end flange 159.
  • the cathode ends 152 are also preferably formed of nickel.
  • the upper cathode end 152 is mechanically and electrically connected to a cathode stud 167, the cathode stud 167 being generally circular in cross section and having at the lower end thereof a reduced diameter portion 168 that extends through the opening 158 in the cathode end 152 and is fixedly secured thereto as by a pair of outwardly directed flanges 169. It will be appreciated that the upper end of the cathode structure 150 is both electrically and mechanically connected to the stud 167.
  • the cathode wall 151 is provided with a sintered porous coating 161 impregnated with a suitable electron emissive oxide material, whereby upon heating of the cathode structure 150, the coating 161 readily emits electrons from the outer surface thereof.
  • the coating 161 is shaped to provide a plurality of outwardly extending projections 162 each having outwardly converging side walls joining a generally circumferentially arranged outer surface 163, a space 164 being provided between the adjacent projections 162. As illustrated, the circumferential extent of the outer surface 163 is substantially equal to the space 164 between the adjacent projections 162.
  • the preferred range of the circumferential extent of each of the outer surfaces 163 is approximately 25% to approximately 60% of the circumferential distance between the centers of adjacent outer surfaces 163.
  • the number of projections 162 provided on the coating 161 is equal to the sum of the number of the anode segments 117 and the number of cooperating rods 125, whereby there are thirty of the projections 162 provided upon the coating 161.
  • the outer surfaces of the coating 161 together with the inner surfaces 118 on the anode members 110, define the interaction space 160 disposed therebetween in which the emitted electrons from the coating 161 interact with the electrical fields and the magnetic fields disposed between the anode structure 101 and the cathode structure 150.
  • the projections 162 combine with the anode segments 117 and with the rods 125 to provide a preferred distribution of the several fields within the interaction space 160 of the device that results in more desirable operating characteristics thereof.
  • One particularly desirable result of the shape of the coating 161 is the minimized back heating of the cathode structure 150', the desirable emitted electrons emanating from the projections 162, and the undesirable emitted electrons emanating from the space 164 between the projections 162, thereby to facilitate the emission of desirable electrons and to suppress the emission of undesirable electrons.
  • each projection 162 is circumferentially displaced relative to the center line of its corresponding anode segment 117 or its corresponding rod 125, as the case may be; more specifically, the center lines of the projection 162 are displaced in a clockwise direction a circumferential distance equal to approximately 40% of the circumferential spacing between the center lines of an adjacent anode segment 117 and an adjacent rod (for example 5 rotation for a 12 spacing or a percentage of 41.8% as illustrated).
  • the circumferential displacement of the projections 162 with respect to the corresponding anode segments or rods is preferably in the range between 0% and approximately 45% of the circumferential spacing between adjacent anode segments and rods, the preferred range being between approximately 25% and 45% of the spacing between adjacent anode segments and rods, a still more preferred range being between approximately 35% and 45% of the spacing between adjacent anode segments and rods.
  • the displacement is on the downstream side, i.e., in the direction of normal initial electron flow from the projections 162.
  • the electron emissive coating 161 is confined between the outer end walls 112 of the anode members 110, the cathode structure being carefully centered with respect to the anode members 110, whereby each of the cathode projections 162 extends axially of the device 100 parallel to the axis thereof and confined between the outer end walls 112.
  • each of the projections 162 varies from end to end of the cathode structure 150. Adjacent to the outer ends of the cathode structure 150, the radial dimensions of each of the projections 162 is preferably greater than about 20% of the spacing between the anode surfaces 118 and the coating 161 on the cathode structure 150. At the longitudinal midpoint of the emissive coating 161, an area 166 of reduced radial dimension is provided, the radial extent of the projections 162 being substantially nil and in certain instances the coating 161 being completely removed at the center reduced portion 166; the portion 166 is opposite the annular passage 123 between the anode members 110 and is provided at this point to match impedances at this area in the device 100.
  • the longitudinal extent of the outer coating portions is substantially equal to the longitudinal extent of the intermediate reduced portions 165, which is in turn substantially equal to the longitudinal extent of the center reduced portion 1'66.
  • difference in the thickness of the coating is approximately mils from one section to the adjacent section of the coating 161.
  • the cathode structure 150 is of the indirectly heated type, and accordingly, there has been provided within the cathode wall 151 a heater 176 in the form of a coiled filament extending substantially the entire length of the cathode wall 151 and spaced inwardly a short distance from the inner surface thereof.
  • the upper end of the heater 176 as viewed in FIG. 2 has an outer end or terminal 177 that extends outwardly into an opening in the lower end of the cathode stud 167, and specifically through an annular opening in the reduced portion 168 thereof and is mechanically and electrically connected to the cathode stud 167, whereby the cathode structure 150 and the heater 176 are both mechanically and electrically connected to the cathode stud 167.
  • the lower end of the heater 17 6 has an outer end or terminal 178 that extends into an opening in the upper end of a conductor 197 and is mechanically and electrically secured thereto.
  • the conductor 197 is preferably formed of copper and extends outwardly and into a threaded connector 196. It will be noted that the heater terminal 178 is spaced from and electrically insulated with respect to the lower end of the cathode structure 150.
  • each of the internal pole pieces 130 is generally cylindrical in shape including a first substantially flat inner plate 131 disposed centrally thereof and disposed in a plane substantially normal to the longitudinal axis of the device 100 and in longitudinal alignment with the interaction space 160.
  • first annular coupling flange 132 Disposed about the periphery of the inner plate 131 and integral therewith is a first annular coupling flange 132 extending outwardly therefrom and carrying on the outer edge thereof an outwardly directed outer plate 133 that is substantially fiat and lying in a plane normal to the axis of the device 100 and being in longitudinal alignment with the adjacent end of the outer axially extending space 120.
  • the outer edge of the outer plate 133 carries a annular and outwardly extending mounting and magnetic coupling flange 134 that has an outer diameter slightly less than the inner diameter of the associated recessed end of the anode sleeve 102 to be received therein and hermetically sealed thereto.
  • each of the inner plates 131 there is provided centrally of each of the inner plates 131 a circular opening 135 in general longitudinal alignment with the adjacent end of the cathode structure 150, and specifically the adjacent end of the cathode wall 151, the opening 135 receiving the terminals of the cathode structure and heater therethrough.
  • the internal pole pieces 130 are each formed of a single sheet of low carbon steel shaped as described by a samping operation, thereby to provide accurate dimensions therefor together with an inexpensive manufacture thereof.
  • the external pole pieces 140 are formed of a material having high magnetic permeability, the preferred material being a low carbon steel, and are copper plated to render the assembly thereof to the anode sleeve 102 readily possible by a brazing operation.
  • each of the external pole pieces 140 is generally circular in shape and each includes a first substantially flat plate 141 dlsposed in a plane substantially normal to the longitudinal axis of the device and disposed in substantially the same plane as the outer plate 133 of the associated internal pole piece 130.
  • the outer plate 141 has an opening centrally thereof circular in shape and having a diameter to receive therethrough the adjacent end of the anode sleeve 102.
  • an annular coupling flange 144 Disposed about the periphery of the opening in the center of the outer plate 141 and integral therewith is an annular coupling flange 144 extending normal thereto and surrounding the adjacent end of the anode sleeve 102, the coupling flange 144 extending from the associated outer plate 141 in the same direction that the coupling flange 132 of the adjacent internal pole piece extends from the associated outer plate 133 thereof.
  • the external pole pieces are each formed of a single sheet of low carbon steel shaped as described by a stamping operation, thereby to provide accurate dimensions thereof together with an inexpensive manufacture thereof.
  • the upper internal pole piece 130 and the upper external. pole piece 140 cooperate to provide an upper composite pole piece and the lower internal pole piece 130 and the lower external pole piece 140 cooperate to provide a lower composite pole piece 145.
  • the pole pieces 130 and 140 in each of the composite pole pieces 145 are not in direct physical and magnetic contact one with the other, there is strong magnetic coupling therebetween, it being pointed out that the sleeve 102 has a reduced wall thickness 106 disposed between the adjacent ones of the pole pieces 130 and 140.
  • each of the internal pole pieces 130 is disposed concentrically within and adjacent to the magnetic coupling flange 144 on the associated external pole piece 140, thereby to provide a large mass of magnetically permeable material that constitutes a low reluctance path for magnetic lines of force between the adjacent ones of the pole pieces 130 and 140.
  • An upper end structure is provided at the upper end of the device 100 as viewed in FIG. 2 and a lower end structure is provided at the lower end of the device 100, the end structures 180 and 190 serving to provide a hermetic seal between the associated internal pole pieces 130 and the associated connections to the cathode structure 150 and/or the heater 176, as the case may be.
  • the upper end structure 180 includes a short tube 181 having the lower end thereof disposed within the opening 135 in the upper internal pole piece 130 and suitably hermetically secured thereto as by brazing and extending upwardly therefrom substantially concentric with the longitudinal axis of the device 100 and the axis of the cathode stud 167.
  • the upper end of the tube 181 receives therein the lower end of an annular insulator 182 which is formed, for example, of a good electrically insulating ceramic, the tube 181 being hermetically sealed to the insulator 182.
  • an annular insulator 182 which is formed, for example, of a good electrically insulating ceramic, the tube 181 being hermetically sealed to the insulator 182.
  • a cap 185 Surrounding the upper end of the insulator 182 and the adjacent portion of the cathode stud 167 is a cap 185, the cap 185 being generally annular in shape and including an annular flange 186 surrounding an outer periphery of the upper end of the insulator 182 and being hermetically sealed thereto.
  • the sleeve 181 and the cap 185 are both formed of a material that can be readily secured both to a metal surface and to a ceramic surface, the preferred material being Fernico alloy, a typical composition being 54% iron, 28% nickel and 18% cobalt.
  • the upper end structure 180 forms a good hermetic seal that also provides electrical insulation between the upper internal pole piece 130 and the output conductor in the form of the cathode stud 167, the end structure 180 likewise providing the necessary mechanical support for the cathode structure 150 to position it within the anode structure 101.
  • a ceramic insulator 191 is provided that is annular in shape and has an outer diameter just slightly less than the diameter of the opening 135 in the lower internal pole piece 130 and an inner diameter just slightly greater than the external diameter of the centering flange 159 on the lower cathode end 152, whereby the insulator 191 serves to center the lower end of the cathode structure 150 with respect to the lower internal pole piece 130.
  • the insulator 191 extends outwardly well beyond the lower internal pole piece 130 and there is provided a seal member 192 annular in shape and surrounding the insulator 191, the seal member 192 including a mounting flange 193 fixedly secured as by brazing to the outer surface of the mner plate 131 on the lower internal pole piece 130, the mounting flange 193 having integral therewith an annular wall 194 carrying an outer flange 195 that is inwardly directed and surrounds and is secured to the outer wall of the insulator 191.
  • the seal member 192 is made of the same material as the sleeve 181 and the cap 185 and is hermetically sealed both to the lower internal pole piece 130 and the insulator 191.
  • the outer end of the insulator 191 carries thereon a second seal member 198 that overlies the outer end thereof and is suitably secured as by brazing to the connector 196, the seal member 198 including an annular flange 199 surrounding the outer end of the insulator 191 and sealed thereto.
  • the seal member 198 is formed of the same material as the seal member 192 and is hermetically sealed both to the insulator 191 and the connector 196.
  • the lower end structure 190 therefore serves hermetically to seal the lower end of the device 100 and also provides electrical insulation between the lower end of the cathode structure 150 and the associated internal pole piece 130 and the heater 176, all while providing for the mechanical support of the lower end of the cathode structure 150' and the lower end of the heater 176.
  • the composite pole pieces 145 arranged adjacent to the opposite ends of the anode structure 101 are utilized for establishing a unidirectional magnetic field extending axially through the several spaces within the anode structure 101, and specifically through the axially extending space 120 and through the interaction space 160, as well as the annular passage 123 and the various spaces between the anode members 110.
  • a pair of magnet coils 210 and 215 has been-provided, the magnet coil 210 being disposed about the upper end of the device as viewed in FIG. 1 and the magnet coil 215 being disposed about the lower end of the device 100 as viewed in FIG. 1.
  • the magnet coils 210 and 215 are both shaped as a torous, are wound of electrically conductive wire, and as illustrated are disposed respectively about magnet yokes 211 and 216, respectively, that include inner annular sections cylinder disposed within the opening in the associated magnet coil. There further are provided outwardly extending end sections or flanges 213 and 218, respectively, about the outer ends of the inner sections 212 and 217 and secured respectively thereto.
  • the end plate 205 is provided on one pair of opposed sides thereof with integral side flanges 206, the side flanges 206 being disposed substantially normal to the end plate 205 and extending upwardly toward the upper end plate 201 and terminating just slightly above the upper edge of the lower magnet coil 215. Enclosing the space between the opposed free edges of the side flanges 202 and 206 are side walls 203, the side walls 203 being disposed inside of the associated ones of the side flanges 202 and 206 and being suitably secured thereto.
  • the other sides of the end plates 201 and 205 are free, whereby the associated sides of the box-like structure 200 are open to receive therethrough a stream of cooling fluid, such as air, that passes around the magnet coils 210 and 215 and around the cooling fins 108, it being noted that the external pole pieces also provide a certain amount of cooling for the device 100.
  • a foraminous sheet such as a screen (not shown) in order to prevent inadvertent contact with the high potentials present in the box-like structure 200.
  • the end plates 201 and 205 and the side flanges 202 and 206 integral therewith are formed of a material that has a high magnetic permeability, such as soft iron and low carbon steel, whereby these parts form a portion of a magnetic return path for the magnetic circuit.
  • the side walls 203 are preferably formed of a material having a low magnetic permeability, a preferred material being aluminum, whereby the side walls 203 provide high reluctance paths for magnetic force lines.
  • the set of opposed sides of the box-like structure 200 on which are disposed the side walls 203 also appear to be open to the magnetic circuit as are the other set of opposed sides of the box-like structure 200, whereby there is substantially no distortion of the magnetic field within the device 100 due to the presence of the materials of construction of the box-like structure 200.
  • a much more uniform magnetic field is provided in the interaction space 160 than would be the case if the side walls 203 were formed of a material having a high magnetic permeability, whereby to provide a low reluctance magnetic path on one set of opposed sides of the boxlike structure 200 while providing a high reluctance magnetic path on the other set of opposed sides of the box-like structure 200.
  • the external pole pieces 140 tend to shunt the leakage field that would otherwise tend to distort the magnetic field in the interaction space, the use of non-magnetic material for the side plates 203 tending to minimize leakage flux which would otherwise tend to saturate the magnetic yokes 211 and 216 and reduce the field intensity in the interaction space 160.
  • a tubular conductor 204 is provided formed of a material that is electrically conductive, the conductor 204 having the lower end thereof received within the upper internal pole piece coupling flange 132 in telescoping relation therewith and is electrically connected thereto, the conductor 204 also being disposed within the upper magnet yoke 211 and extending upwardly and beyond the upper end thereof.
  • the cathode stud 167 at the upper end of the crossed-field discharge device 110 has the outer end thereof disposed below the outer end of the associated magnet yoke 211.
  • the cathode stud 167 and the conductor 204 form a coaxial transmission line that provides output RF terminals for the generator 10, the terminals having applied therebetween the output RF energy from the generator 10.
  • the outer conductor 204 has applied thereto the B+ potential from the conductor 207a which is connected thereto via the input terminal 207, the upper magnet coil 210, the conductor 214, the lower magnet coil 215, the conductor 219, the cooling fin 108, the anode sleeve 102 and the upper internal pole piece 130, the upper internal pole piece 130 being directly connected to the lower end of the outer conductor 204 as illustrated.
  • the outer conductor 204 not only serves as one of the RF terminals for the device 100 but also is in direct electrical connection with the B+ potential on the anode sleeve 102.
  • the cathode stud 167 not only has the RF output energy thereon but has applied thereto both the B potential for the cathode 150 of the device 100 and the low voltage AC potential for energizing the heater 176.
  • a coupler and filter structure 230 In order to accommodate the application to and the presence of the various potentials named on the output terminals 167 and 204 while preventing the introduction of RF energy into the power supply 51, and while preventing the application of the B+ and B- potentials to the output terminals 231 and 241 provided, there has been provided a coupler and filter structure 230. Referring to FIG.
  • the coupler and filter structure 230 includes a first RF output terminal in the form of annular outer conductor 231 which is capacitively coupled to the conductor 204 by a coupler 232, the coupler 232 including a sleeve 233 of electrically insulating dielectric material, the sleeve 233 preferably being formed of a synthetic organic plastic resin, the preferred resin being a tetrafluoroethylene resin sold under the trademark Teflon.
  • the insulating sleeve 233 is disposed around and firmly embraces the outermost end of the tubular conductor 204 and extends upwardly therebeyond; the lower end of the outer conductor 231 is in turn placed in telescoping relationship about the sleeve 233, the lower end of the conductor 231 telescopically overlapping the upper end of the conductor 204 for a distance equal to A of the wavelength of the frequency of operation of the generator 10 in order to provide a portion of a second harmonic filter.
  • An opening is provided in the side wall of the conductor 204 adjacent to the upper end of the generator 10, and joining the conductor 204 and surrounding the opening in the side wall thereof is a second annular conductor 234 that is suitably secured as by welding to the conductor 204 and extends laterally therefrom and to the right as viewed in FIG. 1 with the longitudinal axes of the conductors 204 and 234 disposed substantially normal to each other.
  • insulators 235 and 236 Disposed in the conductor 204 adjacent to the junction thereof with the conductor 234 is a pair of annular insulators 235 and 236 substantially filling the conductor 204 and spaced apart a short distance from each other, the insulators 235 and 236 being formed of an electrically insulating dielectric material, the preferred material being a synthetic organic plastic resin, the preferred resin being a tetrafluoroethylene resin sold under the trademark Teflon.
  • the lower insulator 235 has an opening centrally therein that receives therethrough a portion of a bullet 237 having on the lower end thereof a plurality of spring fingers 237a that resiliently grip the upper end of the cathode stud 167 to form a good electrical contact and mechanical interconnection therewith, a laterally extending flange 2237b extending around the bullet 237 and being disposed below and in supporting relationship with the insulator 235.
  • a probe 238 Extending upwardly through an opening in the center of the bullet 237 is a probe 238 in the form of a solid rod of electrically conductive material, the preferred material being copper.
  • the probe 238 passes through an opening in the center of the insulator 236 and upwardly therebeyond, the insulator 236 having an upstanding flange 236a surrounding the probe 238.
  • a suitable fastener such as a screw 239 is provided at the lower end of the probe 238 and threadedly engages a complementarily threaded opening at the lower end thereof, the head of the screw 239 overlying the lower surface of the bullet 237.
  • annular inner conductor 240 Arranged about and in telescoping relationship with the upper end of the probe 238 is an annular inner conductor 240 that has the lower end resting upon the insulator 236 and surrounding the upstanding flange 236a thereon, the upper end of the conductor 240 having an enlarged section 240a thereon that extends upwardly well beyond the probe 238 and telescopically receives therein a second tubular inner conductor 241 that serves as an RF output terminal for the coupler and filter structure 230, whereby the conductors 231 and 241 provide the RF output terminals for the coupler and filter structure 230.
  • a capacitive coupling is provided between the probe 238 and the conductors 240 and 241 by a coupler 242 including an annular washer 243 formed of an electrically insulating dielectric material, the preferred material being a synthetic organic plastic resin, the preferred resin being a tetrafluoroethylene resin sold under the trademark Teflon.
  • the washer 243 surrounds the upper end of the probe 238 and is seated in the enlarged portion 240a at the upper end of the conductor 240 and serves fixedly to position the upper end of the probe 238 with respect to the conductors 240 and 241.
  • a second fastener in the form of a screw 239 is provided in the upper end of the probe 238 and has a threaded shank threadedly engaged in a complementarily shaped threaded opening in the upper end of the probe 238, the head of the screw 239 engaging the upper surface of the insulating washer 243, whereby the two opposed screws 239 serve fixedly to interlock the insulators 235 13 V and 236, the bullet 237, the conductor 240 and the insulating Washer 243.
  • a cylindrical choke 246 in the form of a tubular conductor that surrounds and receives therethrough the conductor 244 arranged concentrically therewith, the insulator 245 having a laterally extending flange 245a surrounding theconductor 244 and extending in the lefthand end of the choke 246 to position the adjacent end of the choke 246 with respect to the conductor 244.
  • a conductive nut 247 is provided about the conductor 244 adjacent to the righthand end thereof and including a flange 247a extending into the righthand end of the choke 246 to position the adjacent ends of the conductor 244 and the choke 246 with respect to each other.
  • the righthand end of the conductor 244 is threaded as at 2440 and threadedly engages an internally threaded opening in the nut 247 to lock the insulator 245 and the choke 246 against the flange 244b; the threaded end 2440 is connected to an input terminal 208 formed of a conductive metal, the terminal 208 having an enlarged lefthand end 249 having a threaded opening therein to receive the adjacent threaded end 2440 of the conductor 244.
  • the terminal 208 extends outwardly to the right beyond the outer conductor 234 and is connected to a conductor 208a from the associated power supply, the conductor 208a carrying both the B" potential and the heater supply potential.
  • a filter capacitor 248 of the feed through type that is in the form of two layers of conductive foil between which are interposed layers of insulating film, the layers of conductive foil and insulating film being wound to form the capacitor 248, one terminal of the capacitor 248 being connected to the outer conductor 234 and the other terminal of the capacitor 248 being connected to the terminal 208.
  • the inner conductor 204 and the outer conductor 231 telescopically overlap a distance equal to A1 wavelength of the frequency of operation of the generator 10.
  • the probe 238, the inner conductor 240 and the choke 246 are also constructed to have a length equal to A Wavelength of the frequency of operation of the generator 10.
  • the outer conductors 204234 serve as a B+ input terminal, the con ductor 204 being directly connected to the conductor 219 by which B+ potential is applied to the outer sleeve 102, and the terminal 208 services as the B input terminal and is connected to the cathode 150 via the conductor 244, the probe 248, the bullet 237, and the cathode stud 167 (see FIG. 3 also), whereby to apply B potential to the cathode 150.
  • the terminal 208 also serves as an input terminal for the low voltage AC filament supply and is connected to one end of the heater 176 via the conductor 244, the probe 238, the bullet 237 and the cathode stud 167, whereby to apply low voltage AC potential to the upper end of the heater 176.
  • the connector 196 at the lower end of the device 110 is connected to a filter capacitor of the feed through type, and more specifically is connected to the input terminal 209 that has the adjacent end thereof internally threaded and receives the threaded outer end of the terminal 196 therein.
  • a tubular conductor 221 is provided formed of a metal that is electrically conductive, the conductor 221 having the upper end thereof received Within the lower internal pole piece coupling flange 132 in telescoping relation therewith and being electrically connected thereto, the conductor 221 being disposed-within the lower magnet yoke 216 and extending downwardly and beyond the lower end thereof.
  • a cover 222 formed of conductive metal and including a flange 224 surrounding and in telescoping relationship with the lower end of the conductor 221 and mechanically and electrically secured thereto.
  • a filter capacitor 226 Disposed between the terminal 209 and the cover 222 is a filter capacitor 226 of the same type of construction as the filter capacitor 248 described above, one of the terminals of the filter capacitor 226 being connected to the cover 222 and the other terminal of the filter capacitor 226 being connected to the terminal 209, a flange 227 being provided on the exterior of the filter capacitor 226 in overlying relationship with the cover 222.
  • the filter capacitor 226 serves to by-pass RF energy from the terminal 209 to the outer conductor 221 through the cover 222, thereby to prevent the introduc tion of RF energy into the associated power supply via the conductor 209a.
  • the crossed-field discharge device of the above mentioned application Ser. No. 559,267 when incorporated in a large magnet structure has an operating efficiency of about 35%, but when that device is placed in a compact magnet structure, i.e., when the magnet coils were placed close to the magnetic pole pieces within the device, the efliciency was reduced to about 30%.
  • the same device of application Ser. No. 559,267 was equipped with the external pole pieces of the present invention and was placed in the improved box-like structure 200 incorporating the side plates 203 of non-magnetic material, the effiicency thereof was increased to 40%, whereby it will be seen that the present invention presents a substantial increase in the efficiency of the crossed-field discharge device.
  • a crossed-field discharge device comprising an envelope, an anode structure disposed in said envelope and defining an axially extending space, an axially extending cathode structure disposed in said axially extending space and cooperating with said anode structure to define an axially extending annular interaction space therebetween, said cathode structure including an electron emissive element disposed within said anode structure and adjacent to the inner portion of said interaction space, a pair of internal identically constructed magnetic pole pieces disposed interiorly of said envelope and respectively arranged adjacent to the opposite ends of said anode structure for establishing a unidirectional magnetic field extending axially through said interaction space, and a pair of identically constructed external magnetic pole pieces disposed exteriorly of said envelope and respectively arranged adjacent to said internal pole pieces and in surrounding relation therewith and extending radially outwardly therefrom, each one of said internal pole pieces cooperating with the adjacent one of said external pole pieces to provide a composite pole piece, the dimensions of said composite pole pieces normal to the axis of said interaction space being
  • each of said internal pole pieces has an axially extending annular flange thereon disposed against said envelope
  • each of said external pole pieces has an axially extending annular flange thereon disposed against said envelope; the flange on each of said internal pole pieces being disposed in radial alignment with the flange on the adjacent one of said external pole pieces.
  • a crossed-field discharge device comprising an envelope, an annular anode structure disposed in said envelope and defining an annular axially extending space, an axially extending annular cathode structure disposed in said axially extending space and cooperating with said anode structure to define an axially extending annular interaction space therebetween, said cathode structure including an electron emissive element disposed within said anode structure and adjacent to the inner portion of said interaction space, a pair of identically constructed annular internal magnetic pole pieces each having a generally circular periphery and disposed interiorly of said envelope and respectively arranged adjacent to the opposite ends of said anode srtucture for establishing a unidirectional magnetic field extending axially through said interaction space, and a pair of identically constructed annular external magnetic pole pieces each having a generally circular periphery and disposed exteriorly of said envelope and respectively arranged adjacent to said internal pole pieces and in surrounding relation therewith and extending radially outwardly therefrom, each one of said internal pole
  • each of said internal pole pieces has an axially extending annular flange thereon disposed against said envelope
  • each of said external pole pieces has an axially extending annular flange thereon disposed against said envelope, the flange on each of said internal pole pieces being disposed in radial alignment with the flange on the adjacent one of said external pole pieces.
  • a crossed-field discharge device comprising an annular sleeve, a pair of annular anode members disposed Within said sleeve, a plurality of rods disposed adjacent to the inner surfaces of said anode members, said sleeve and said anode members being electrically connected at the opposite ends of said device and said rods being electrically connected to said anode members at the outer ends thereof, said sleeve and said anode members cooperating to define a first axially extending space therebetween and said anode members cooperating to define a second axially extending space therethrough and said anode members being spaced apart axially to provide a lateral passage therebetween interconnecting said axially extending spaces, each of said anode members having a plurality of radially extending anode segments on the inner surface thereof projecting radially into said second axially extending space and providing a plurality of axially extending anode recesses therebetween, said rods being respectively disposed in said an
  • a microwave assembly comprising a crossed-field discharge device including an envelope, an anode structure disposed in said envelope and defining an axially extending space, an axially extending cathode structure disposed in said axially extending space and cooperating with said anode structure to define an axially extending annular interaction space therebetween, said cathode structure including an electron emissive element disposed within said anode structure and adjacent to the inner portion of said interaction space, a pair of internal magnetic pole pieces disposed interiorly of said envelope and respectively arranged adjacent to the opposite ends of said anode structure for establishing a unidirectional magnetic field extending axially through said interaction space, a pair of external magnetic pole pieces disposed exteriorly of said envelope and respectively arranged adjacent to said internal pole pieces and in surrounding relation therewith and extending radially outwardly therefrom, each one of said internal pole pieces cooperating with the adjacent one of said external pole pieces to provide a composite pole piece, the dimensions of said composite pole pieces normal to the axis of said interaction space being substantially greater
  • a crossed-field discharge device comprising an envelope, an anode structure disposed in said envelope and defining an axially extending space, an axially extending cathode structure disposed in said axially extending space and cooperating with said anode structure to define an axially extending annular interaction space therebetween, said cathode structure including an electron emissive element disposed within said anode structure and adjacent to the inner portion of said interaction space, a pair of identically constructed internal magnetic pole pieces disposed interiorly of said envelope and respectively arranged adjacent to the opposite ends of said anode structure for establishing a unidirectional magnetic field extending axially through said interaction space, each of said internal magnetic pole pieces comprising an annular inner plate disposed in a plane substantially normal to the longitudinal axis of said device, a first annular axially extending flange disposed around the periphery of said inner plate integral therewith and extending outwardly therefrom, an annular outer plate integral with the outer edge of said first flange and extending outwardly
  • a crossed-field discharge device comprising an envelope, an annular anode structure disposed in said envelope and defining an annular axially extending space, an axially extending annular cathode structure disposed in said axially extending space and cooperating with said anode structure to define an axially extending annular interaction space therebetween, said cathode structure including an electron emissive element disposed within said anode structure and adjacent to the inner portion of said interaction space, a pair of identically constructed annular internal magnetic pole pieces each having a generally circular periphery and disposed interiorly of said envelope and respectively arranged adjacent to the opposite ends of said anode structure for establishing a unidirectional magnetic field extending axially through said interaction space, each of said internal magnetic pole pieces comprising an annular inner plate disposed in a plane substantially normal to the longitudinal axis of said device, a first annular axially extending flange disposed around the periphery of said inner plate integral therewith and extending outwardly therefrom, an annular
  • a crossed-field discharge device comprising an annular sleeve, a pair of annular anode members disposed within said sleeve, a plurality of rods disposed adjacent to the inner surfaces of said anode members, said sleeve and said anode members being electrically connected at the opposite ends of said device and said rods being electrically connected to said anode members at the outer ends thereof, said sleeve and said anode members cooperating to define a first axially extending space therebetween and said anode members cooperating to define a second axially extending space therethrough and said anode members being spaced apart axially to provide a lateral passage therebetween interconnecting said axially extending spaces, each of said anode members having a plurality of radially extending anode segments on the inner surface thereof projecting radially into said second axially extending space and providing a plurality of axially extending anode recesses therebetween, said rods being respectively disposed in said an

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US584769A 1966-10-06 1966-10-06 Crossed-field discharge device and improved magnetic pole structures therefor Expired - Lifetime US3459994A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2812988A1 (de) * 1978-03-06 1978-10-05 Coulter Electronics Verfahren und anordnung zur erfassung der beta-thalassaemie minor

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2787728A (en) * 1954-03-24 1957-04-02 Litton Industries Inc Electron discharge device with toroidal permanent magnet
GB908842A (en) * 1959-09-24 1962-10-24 Ass Elect Ind Magnetron
US3158780A (en) * 1961-12-21 1964-11-24 Horst W A Gerlach Voltage-tuneable magnetron

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2787728A (en) * 1954-03-24 1957-04-02 Litton Industries Inc Electron discharge device with toroidal permanent magnet
GB908842A (en) * 1959-09-24 1962-10-24 Ass Elect Ind Magnetron
US3158780A (en) * 1961-12-21 1964-11-24 Horst W A Gerlach Voltage-tuneable magnetron

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2812988A1 (de) * 1978-03-06 1978-10-05 Coulter Electronics Verfahren und anordnung zur erfassung der beta-thalassaemie minor

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GB1196035A (en) 1970-06-24
NL6713650A (de) 1968-04-08
CH487497A (de) 1970-03-15

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