US2463524A - Electron discharge device - Google Patents

Electron discharge device Download PDF

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Publication number
US2463524A
US2463524A US582046A US58204645A US2463524A US 2463524 A US2463524 A US 2463524A US 582046 A US582046 A US 582046A US 58204645 A US58204645 A US 58204645A US 2463524 A US2463524 A US 2463524A
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US
United States
Prior art keywords
anode
cathode
arms
mode
magnetron
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US582046A
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English (en)
Inventor
Palmer P Derby
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.)
Raytheon Co
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Raytheon Manufacturing Co
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Filing date
Publication date
Application filed by Raytheon Manufacturing Co filed Critical Raytheon Manufacturing Co
Priority to US582046A priority Critical patent/US2463524A/en
Priority to GB30390/45A priority patent/GB626930A/en
Application granted granted Critical
Publication of US2463524A publication Critical patent/US2463524A/en
Priority to DER4396A priority patent/DE974565C/de
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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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
    • H01J23/16—Circuit elements, having distributed capacitance and inductance, structurally associated with the tube and interacting with the discharge
    • H01J23/18—Resonators
    • H01J23/22—Connections between resonators, e.g. strapping for connecting resonators of a magnetron

Definitions

  • This invention relates to a magnetron microwave oscillator.
  • An object of this invention is to produce such an oscillator which can operate successfully with high power output and efficiency on continuous wave operation.
  • Another object is to devise such an oscillator in which the separation between the principal mode and the closest adjacent mode is greater than a critical value below which successful continuous wave operation does not occur.
  • a further object is to devise such a magnetron in which the cathode structure is arranged to conduct away large amounts of heat generated at the cathode during continuous wave operation, said conduction to occur at a rate sufficient to prevent the overheating of the cathode.
  • Fig. l is a vertical section through one form of my invention
  • Fig. 2 is a horizontal section taken along line 2-4 of Fig. 1;
  • Fig. 3 is a broken-away perspective view showing two of the anode paddles.
  • Fig. 4 is a set of curves showing in a qualitative manner certain relationships within the magnetron which may be taken into consideration in embodying the principles of my invention in a practical device.
  • the magnetron illustrated inFigs. 1-3 comprises a tubular anode structure I made of a cylinder of conducting material, such as copper.
  • a plurality of radially-disposed plates 2 likewise formed of conducting material, such as copper, are soldered in place along the inner surface of the hollow cylinder I.
  • Each pair of plates, together with the intervening portion of the cylinder I, define a cavity resonator.
  • the inner ends of the radial plates are adapted to serve as anode faces for receiving electrons emitted from the centrally-disposed cathode 3.
  • Alternate plates 2 are electrically connected bymeans of conducting straps 4, 5, 6 and l.
  • the straps 4 and 5 are located at one end of the anode structure, the strap 4 being electrically connected to alternate plates 2 and the strap 5 connected to the intervening alternate plates.
  • the strap 6 is connected to those plates to which the strap 5 is connected, and the strap 1 is connected to those plates to which the strap 4 is connected.
  • Such a strap arrangement substantially decreases the tendency for the device to operate in various It is particularly effective in tional hollow conductor, not shown, may be connected to the pipe 9 so as to surround the con ductor 8', forming therewith a concentric transmission line through which the energy generated by the oscillator may be fed.
  • the upper and lower ends of the cylinder I are closed by the upper and lower caps II and I2 formed of a suitable conducting material, such as copper, and hermetically soldered into the ends of the cylinder l.
  • the upper cap H is provided with a central opening into which a magnetic pole piece 13 is hermetically soldered so as to close said opening.
  • the lower cap 12 is provided with a central opening in which is hermetically soldered a lower pole piece M.
  • the pole pieces l3 and M are formed of highly permeable iron. Any suitable form of external magnet may be applied to these pole pieces so as to impart opposite polarities thereto, whereupon the proper magnetic field is 'set up within the magnetron v about the cathode 3.
  • the cathode 3 is formed with a central tubular section l5, the outer surface of which is coated with firmly adherent electron-emitting oxides. Connected to the upper and lower ends, respectively, of the central section I5 are enlarged hollow end sections l6 and I1.
  • the entire assembly l5, I6 and Il may be made of a suitable metal, such as nickel.
  • a heating coil [8 is supported One end IQ of the coil" within the section l5.
  • the end section I8 is welded within and to the hollow section l6, and the lower end 20 extends through and beyond the lower section [1.
  • the lower end 20 of the heater is in turn welded to a lead-in conductor 2!.
  • the pole pieces [3 and M are provided, respectively, with bores 22 and 23, into which are received the enlarged end sections it and ll of the cathode 3.
  • the end section I! is provided with .a reduced extension 24 which fits into the upper end of a hollow rod 25 made of a highly' conductive material, such as copper.
  • the other end 1 The rod is soldered in the lower end of the hollow rod 255- Supported on the outside of the lowerendof said rod 25 is a heat radiator 32 provided with a plurality of heat-radiating fins-.332
  • the end sections I6 and I1 extendfor a considerable distance within the massivemetal bodies provided by the polepieces l3 and I4; Heat is. thus readily radiated from the end.- sections I6 and I! to the massive bodies l3 and M from which the heat may be conducted very rapidly.
  • the bores 22 and 23'withinthe pole pieces l3 and Himay be provided with black surfaces so. as to more readily absorb the energy radiated from the endsections l6 and I1.
  • the lower section IT- is in intimate contact with the highly conducting: rod 25 so that in addition. to the radiation the heat-is led away from the: end section I! by conduction through the. rod 25..
  • the heat radiator 32 forms an excellent means-forv dissipating this heat. In. some. instances it may be desired to blow air against the. heat radiator. 32 to conduct the; heat away more: rapidly.
  • the magnetron should be operated with a relatively high ratio between the voltage between the anode and cathodeandlthe average current flow between the anodeand cathode. I have found that a ratio of the order of1,0'00'volts/amp. or greateris desirable. This is a dynamic ratio and not a static one. The ratio represents the change in anode voltage required to produce a desired change in anode. current.
  • the mode index number is an expression of the number of voltage maxima points which exist throughout the tube structure during the generation of oscillations.
  • N represents the number of anode plates 2 within the tube
  • n represents the indexnumber of the principal mode
  • the percentage mode separation between the principal mode and the next lower mode is where Kn i'sthe Wave length ofthe'principal mode and ⁇ n-1 is the wave length. of the next lower index numbermode at which the.
  • the desired critical mode separation may readily be reached and in most instances greatly exceeded.
  • the percentage mode separation must be substantially greater than the critical value, due to the following reasons.
  • the tube will start oscillating, and if the mode separation is greater than the critical value, these, oscillations will be in the principal mode.
  • the mode separation is only slightly greater than the critical value, the anode-cathode current can be raised only a slight amount before additional modes are excited, thus rendering the tube unfit for continuous wave work.
  • the mode separation As the mode separation is increased beyond the critical value, the greater may be the increase or excursion of the anode-cathode current. It will be seen that the amount of power which such a tube can deliver is dependent on the magnitude of the anode-cathode current excursion. Thus in a practical tube the mode separation should be substantially greater than the critical value. Thus, for example, in a tube having sixteen anode arms, the critical percentage mode separation is about 11%. Yet for practical purposes I prefer to construct the tube with a percentage mode separation of the order of 50% or greater.
  • L the total lumped inductance of one cavity resonator between two of the arms 2;
  • C the total lumped capacity of said one cavity resonator. This includes the added capacity introduced into the resonator by the adjacent straps 4-4;
  • Cs the capacity of the straps :between the anode arms defining said one cavity resonator
  • n the index number of the mode being considered.
  • A LS+M5; LS being the self-inductance of that part of one strap extending between the two anode arms of said one cavity .and Ms being the mutual inductance between those portions of two adjacent straps which extend between said two anode arms; and
  • the factor in Equation 6 containing sin 0 can be made to predominate and give the desired mode separation. This can be done by making the strap capacity Cs larger. Such large strap capacity may :be obtained by increasing the areas of the straps facing each other.
  • Equation rectly interconnected by anotherstrap adjacent 6 for the two values An and Aa-canbe expressed as said first-mentioned strap, said magnetron. hav- 21w) 1 2L 1 1 2 (Equation 8) I: -i( c.(L.+M. -1)] and 21w 1 2L f 1 LC 1 Tin-Hi1s 1 21117 v N (Equatlm 9) T OI(L+MI) 1 IE-l H :c0t N 7r 1 2 sin 2 1rwherevis the velocity of light. .25 ing a percentage mode separation substantially If a tube is constructed to scale as illustrated greater thanthe critical value in the drawings, then such a tube will have in- 1 corporated. in it the principles of my invention and will operate successfully on continuous wave. 1
  • s the capacity of the straps between tWo adjacent-arms
  • .A Ls+Ms, Ls being said selfinductance and Ms being said mutual inductance.
  • a magnetron comprising a cathode, an. anode structure surrounding said cathode and comprising a plurality of anodearms disposed about said cathode, each arm having an electron-receiving face, and each pair of adjacent arms constituting the side walls of a cavity resonator, alternate anode arms .being directly interconnected by a strap, the intervening anode arms being directly interconnected by another strap, L, C, Ls, Cs and Ms being related in the equations "2.
  • a magnetron comprising a-cathodaan anode I n I a and so that is substantially greater than the critical value l ⁇ V 1 2 the above symbols having the following values:
  • a magnetron comprising a cathode, an anode structure surrounding said cathode and comprising a plurality of anode arms disposed about said cathode, each arm having an electron-receiving face, and each pair of adjacent arms constituting the side walls of a cavity resonator, said cathode comprising a central electron emitting portion of relatively low heat capacity, end sections of metal and of relatively high heat capacity connected to the ends of said central portion and in good heat conducting relation therewith, two pole pieces supported at opposite ends of said anode structure, said pole pieces being of magnetic material and of relatively massive size relative to said end sections, said pole pieces being provided with elongated bores, said end sections projecting into said bores, each for a substantial distance.
  • a magnetron comprising a cathode, an anode structure surrounding said cathode and comprising a plurality of anode arms disposed about said cathode, each arm having an electron-receiving face, and each pair of adjacent arms constitutin the side walls of a cavity resonator, said cathode comprising a central electron emitting portion of Number relatively low heat capacity, an end section of metal and of relatively high heat capacity connected to one end of said central portion and in good heat conducting relation therewith, a pole piece supported at one end of said anode structure, said pole piece being of magnetic material and of relatively massive size relative to said end section, said pole piece being provided with an elongated bore, said end section projecting into said bore for a substantial distance, the opposite end of said central portion being in good heat conducting relation with a highly heat conductive rod, said rod extending exteriorly of said anode structure and carrying a heat radiator.
  • a magnetron comprising a cathode, an anode structure surrounding said cathode and comprising a plurality of anode arms disposed about said cathode, each arm having an electron-receiving face, and each pair of adjacent arms constituting the side walls of a cavity resonator, said cathode comprising a central electron emitting portion of relatively low heat capacity, end sections of metal and of relatively high heat capacity connected to the ends of said central portion and in good heat conducting relation therewith, two pole pieces supported at opposite ends of said anode structure, said pole pieces being of magnetic material and of relatively massive size relative to said end sections, said pole pieces being provided with elongated bores, said end sections projecting into said bores, each for a substantial distance, one of said end sections being in good heat conducting relation with a highly heat conductive rod, said rod extending exteriorly of said anode structure and carrying a heat radiator.

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  • Microwave Tubes (AREA)
US582046A 1945-03-10 1945-03-10 Electron discharge device Expired - Lifetime US2463524A (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
US582046A US2463524A (en) 1945-03-10 1945-03-10 Electron discharge device
GB30390/45A GB626930A (en) 1945-03-10 1945-11-13 Improvements in or relating to magnetrons
DER4396A DE974565C (de) 1945-03-10 1950-10-04 Magnetronroehre, deren jeweils gleichphasig schwingende Anodenarme durch jeweils einen Leiter miteinander verbunden sind

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US582046A US2463524A (en) 1945-03-10 1945-03-10 Electron discharge device

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US2463524A true US2463524A (en) 1949-03-08

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DE (1) DE974565C (de)
GB (1) GB626930A (de)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2617056A (en) * 1949-02-10 1952-11-04 Westinghouse Electric Corp Electron discharge device for high frequency
US2716711A (en) * 1951-01-11 1955-08-30 English Electric Valve Co Ltd Magnetrons
US2719240A (en) * 1946-03-14 1955-09-27 Laurence R Walker Cathode structure
US3305693A (en) * 1963-01-02 1967-02-21 Litton Industries Inc Interdigital magnetron including means for suppressing undesired modes of operation by separating the frequency of possible undesired operating modes

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2063342A (en) * 1934-12-08 1936-12-08 Bell Telephone Labor Inc Electron discharge device
GB509102A (en) * 1937-10-08 1939-07-11 Electricitatsgesellschaft Sani Improvements in vacuum electric discharge apparatus
US2348986A (en) * 1940-10-24 1944-05-16 Rca Corp Resonant cavity magnetron
US2412824A (en) * 1942-06-22 1946-12-17 Gen Electric Magnetron
US2417789A (en) * 1941-12-01 1947-03-18 Raytheon Mfg Co Magnetron anode structure

Family Cites Families (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1558120A (en) * 1922-04-03 1925-10-20 Simpson Frederick Grant Radio receiving system
DE869649C (de) * 1934-03-01 1953-03-05 Julius Pintsch K G Elektronenroehre zum Anfachen, insbesondere Verstaerken, Erzeugen oder Empfangen vonultrahochfrequenten, elektromagnetischen Schwingungen
GB445084A (en) * 1934-08-21 1936-04-02 Telefunken Gmbh Improvements in or relating to electron discharge devices
DE663509C (de) * 1934-08-21 1938-08-08 Telefunken Gmbh Mehrfach geschlitzte Magnetronroehre
DE730623C (de) * 1935-11-02 1943-01-14 Electricitaetsgesellschaft San Magnetfeldroehre zur Erzeugung ultrakurzer Wellen
US2123728A (en) * 1935-11-29 1938-07-12 Telefunken Gmbh Magnetron
DE758546C (de) * 1938-11-20 1953-03-23 Telefunken Gmbh Magnetfeldroehre mit vier oder mehr in zwei Gruppen arbeitenden Anodensegmenten
BE446912A (de) * 1940-07-27

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2063342A (en) * 1934-12-08 1936-12-08 Bell Telephone Labor Inc Electron discharge device
GB509102A (en) * 1937-10-08 1939-07-11 Electricitatsgesellschaft Sani Improvements in vacuum electric discharge apparatus
US2348986A (en) * 1940-10-24 1944-05-16 Rca Corp Resonant cavity magnetron
US2417789A (en) * 1941-12-01 1947-03-18 Raytheon Mfg Co Magnetron anode structure
US2412824A (en) * 1942-06-22 1946-12-17 Gen Electric Magnetron

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2719240A (en) * 1946-03-14 1955-09-27 Laurence R Walker Cathode structure
US2617056A (en) * 1949-02-10 1952-11-04 Westinghouse Electric Corp Electron discharge device for high frequency
US2716711A (en) * 1951-01-11 1955-08-30 English Electric Valve Co Ltd Magnetrons
US3305693A (en) * 1963-01-02 1967-02-21 Litton Industries Inc Interdigital magnetron including means for suppressing undesired modes of operation by separating the frequency of possible undesired operating modes

Also Published As

Publication number Publication date
GB626930A (en) 1949-07-25
DE974565C (de) 1961-02-09

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