EP0352961B1 - Klystrode-Frequenzvervielfacher - Google Patents

Klystrode-Frequenzvervielfacher Download PDF

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Publication number
EP0352961B1
EP0352961B1 EP19890307345 EP89307345A EP0352961B1 EP 0352961 B1 EP0352961 B1 EP 0352961B1 EP 19890307345 EP19890307345 EP 19890307345 EP 89307345 A EP89307345 A EP 89307345A EP 0352961 B1 EP0352961 B1 EP 0352961B1
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EP
European Patent Office
Prior art keywords
tube
gap
frequency
cavity
grid
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
EP19890307345
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English (en)
French (fr)
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EP0352961A1 (de
Inventor
Louis T. Zitelli
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.)
Varian Medical Systems Inc
Original Assignee
Varian Associates Inc
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Publication date
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J25/00—Transit-time tubes, e.g. klystrons, travelling-wave tubes, magnetrons
    • H01J25/02—Tubes with electron stream modulated in velocity or density in a modulator zone and thereafter giving up energy in an inducing zone, the zones being associated with one or more resonators
    • H01J25/04—Tubes having one or more resonators, without reflection of the electron stream, and in which the modulation produced in the modulator zone is mainly density modulation, e.g. Heaff tube

Definitions

  • the invention pertains to linear-beam electron tubes in which the beam is density-modulated by a control grid.
  • Such tubes have been found useful for generating amplitude-modulated ultra-high-frequency radio waves such as television broadcast transmission, with efficiency superior to klystrons.
  • Radio transmitters have generally used grid-controlled electron tubes such as tetrodes.
  • UHF ultra-high frequency range
  • the gridded tubes reached their performance limits of power or frequency due to the transit times of electrons across the gaps between electrodes becoming comparable to the period of the generated wave.
  • the first development to overcome these limits was the UHF klystron in which transit time is taken advantage of rather than being unwanted.
  • the klystron is very inefficient for amplifying an amplitude-modulated wave such as the standard TV signal where amplitude corresponds to brightness.
  • the klystron has to have enough power in the beam to generate the signal peaks, such as black and the still stronger synchronization pulses.
  • the average power needed for an average signal is several times smaller, but the unused beam power is wasted as heat in the spent-beam collector.
  • Preist and Shrader made a high-power tube using klystron beam technology and a much larger carbon grid to which the rf signal was applied in class B or class C modulation.
  • the video-frequency power envelope of the beam is thus just what is needed to generate the instantaneous signal amplitude.
  • the power efficiency in TV transmission was increased greatly.
  • US-A-4611149 can be taken to describe a linear-beam frequency-multiplier electron vacuum tube comprising an electron emissive cathode; an electron-permeable control grid closely spaced from the emissive surface of said cathode; means for supplying a high-frequency signal voltage between said cathode and said grid; an anode spaced from said grid and facing said emissive surface, apertured for passage of an electron beam from said cathode; a hollow conductive drift tube for transmitting said beam beyond said anode, the drift tube being formed with a first and a second gap, the second gap being on one side of the first gap near the anode; a first hollow cavity located around the first gap in said drift tube to form a re-entrant cavity resonant at a frequency near the frequency of said signal voltage; a second hollow cavity located around the second gap in said drift tube to form a re-entrant cavity resonant at a frequency higher than said signal voltage frequency; means for extracting wave energy at
  • the present invention is set out in Claim 1.
  • Figure 1 illustrates a tube which has a thermionic cathode with preferably concave emitting surface 11, heated by a radiant wire coil 12.
  • a convergent beam of electrons 14 is drawn from emitter 11 by a hollow anode 16.
  • Directly in front of emitter 11 is an electron-permeable grid, preferably of pyrolytic graphite bars 18 bounding apertures 20.
  • Beam 14 is converged toward anode 16 by the convergent electrostatic field. It passes through anode 16 and an annular ferro-magnetic polepiece 22 which forms one terminus of a strong axial magnetic focusing field generated by a surrounding solenoid coil (not shown). Beam 14 then passes through a hollow metallic drift tube 24 and crosses an interaction gap 26 between input drift tube 24 and an exit drift tube 28. Drift tubes 24 and 28 form the center conductor of a coaxial cavity 30, resonant at preferably a frequency just above the frequency band of the tube's input signal.
  • Cavity 32 is resonant at a harmonic of the band-center input frequency and is excited by the harmonic component of the modulated beam current.
  • beam 14 After leaving harmonic output cavity 32, beam 14 passes through a second annular polepiece 37 which terminates most of the axial field. Beam 14 then expands under its own space-charge repulsion and is collected on the hollow, inner surface of a beam collector 38. The heat energy dissipated is removed by a coolant 40 (such as water) circulating from a coolant pipe 42.
  • a coolant 40 such as water
  • an input signal to be amplified and frequency-multiplied is fed in from a coaxial transmission line 46 through a coaxial dielectric vacuum window 48 to the space between the grid support 50 (usually at rf ground) and cathode support 52. This space may be partially blocked from input line 46 to form a resonant cavity to properly match impedances.
  • Drift tube 34 of harmonic cavity 32 is smaller in diameter than drift tube 24 of fundamental cavity 30, to provide good interactive coupling between beam and cavity at the higher frequency.
  • the beam size is tapered down by a gradual increase in strength of the focussing magnetic field by increasing the wire turns per unit length of the solenoid. Shaping of polepieces 22, 37 to concave-convex shapes may also be used to generate the tapered field. In the strong "confined flow" focussing, the electrons follow the magnetic flux lines.
  • Useful harmonic energy is extracted from output cavity 32 via a coupling orifice 54 into an output waveguide 56 which is sealed off by a dielectric vacuum window 57.
  • FIG. 4 shows calculated trajectories (in rf phase) of sample electrons where harmonic content of beam current is enhanced by bunching at a harmonic frequency.
  • FIG. 2 is a graph of calculated harmonic components of beam current in the present frequency multiplier, plotted as functions of distance Z from the amplitude-modulating grid.
  • Graph 60 is the fundamental component having a decreasing value 62 after leaving grid 18 due to space-charge debunching.
  • beam 14 receives velocity modulation which in following drift tube 28 increases the A.C. component 64.
  • the A.C. component reaches a maximum value 66.
  • an output circuit with a gap at the position of harmonic gap 36 but resonant at the fundamental frequency gives a conversion efficiency of 87%.
  • the second graph shows the second harmonic component 70 of beam current.
  • the space-charge debunching 72 is more severe than for the fundamental current 60 due to the shorter wavelength.
  • the second harmonic current also increases faster due to the increased number of wavelengths traversed.
  • the peak value 76 is reached at about the same distance as that of fundamental 60. At this point output gap 36 is located.
  • the conversion efficiency for second harmonic power was calculated as 75%, a value completely out of reach in klystrons or simple grid-controlled tubes.
  • the second or third harmonic would be used.
  • the limits of power and frequency available from the multiplier are greatly extended.

Landscapes

  • Microwave Tubes (AREA)
  • Microwave Amplifiers (AREA)

Claims (10)

  1. Linearstrahlelektronenröhre für einen Frequenzvervielfacher mit:
    einer Elektronenemissionskathode (10) zum Emittieren eines Elektronenstrahls;
    einem elektronendurchlässigen Steuergitter (11) zum Steuern des Strahls, das in engem Abstand von der emittierenden Oberfläche der Kathode angeordnet ist;
    Mitteln (46 bis 52) zum Anlegen einer hochfrequenten Signalspannung zwischen Kathode und Gitter;
    einer Anode (16), die vom Gitter beabstandet und der emittierenden Oberfläche gegenüberliegend angeordnet ist, mit einer Öffnung zum Durchgang des Elektronenstrahls;
    einer hohlen leitfähigen Driftröhre (24, 28) zum Transmittieren des Strahls über die Anode hinaus, mit einem ersten und einem zweiten Spalt, wobei der zweite Spalt auf der Seite des ersten Spalts entfernt von der Anode angeordnet ist;
    einem ersten Hohlraum (30) zur Geschwindigkeitsmodulation des Strahls, wobei der erste Hohlraum um den ersten Spalt herum in der Driftröhre angeordnet ist, um einen Reentrant-Resonator zu bilden, der in der Nähe der Frequenz der Signalspannung resoniert;
    einem zweiten Hohlraum (32), der um den zweiten Spalt der Driftröhre angeordnet ist, um einen Reentrant-Resonator zu bilden, der in der Nähe einer Harmonischen der Frequenz der Signalspannung resoniert;
    Mitteln (54 bis 57) zur Entnahme von Wellenenergie mit der Frequenz der Harmonischen am zweiten Hohlraum; und
    Mitteln (38) zum Aufnehmen des Strahls in Strahlrichtung hinter dem zweiten Hohlraum.
  2. Röhre nach Anspruch 1, bei der der erste Hohlraum (30) eine Resonanzfrequenz aufweist, die höher ist als das Frequenzband des Signals und die niedriger ist als das Frequenzband der Harmonischen.
  3. Röhre nach Anspruch 1 oder 2, bei der der zweite Hohlraum (32) eine Resonanzfrequenz aufweist, die sich der Mitte des Frequenzbandes der Harmonischen annähert.
  4. Röhre nach einem der Ansprüche 1 bis 3, bei der das Gitter (11) aus pyrolytischem Graphit besteht.
  5. Röhre nach einem der Ansprüche 1 bis 4, bei der die Mittel zum Zuführen der Signalspannung einen die Kathode und das Gitter verbindenden Resonanzkreis enthalten.
  6. Röhre nach einem der Ansprüche 1 bis 5, bei der die Driftröhre (24, 28) an dem zweiten Spalt (36) schmaler ist, als an dem ersten Spalt (26).
  7. Röhre nach einem der Ansprüche 1 bis 6, bei der der zweite Spalt (36) kürzer ist als der erste Spalt (26).
  8. Röhre nach einem der Ansprüche 1 bis 7, mit Mitteln (22, 37) zum Erzeugen eines dauerhaften Magnetfeldes in Strahlrichtung zwischen der Anode und dem zweiten Spalt.
  9. Röhre nach Anspruch 8, bei der die Magnetfeldmittel ferromagnetische Polelemente (22, 37) enthalten, welche die Driftröhre umgeben.
  10. Röhre nach Anspruch 8, bei der die Magnetfeldmittel ein Magnetfeld erzeugen, das an dem zweiten Spalt stärker ist als an dem ersten Spalt, wobei der Strahl zwischen den Spalten zusammengedrückt wird.
EP19890307345 1988-07-25 1989-07-20 Klystrode-Frequenzvervielfacher Expired - Lifetime EP0352961B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US22349088A 1988-07-25 1988-07-25
US223490 1988-07-25

Publications (2)

Publication Number Publication Date
EP0352961A1 EP0352961A1 (de) 1990-01-31
EP0352961B1 true EP0352961B1 (de) 1994-09-07

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Family Applications (1)

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EP19890307345 Expired - Lifetime EP0352961B1 (de) 1988-07-25 1989-07-20 Klystrode-Frequenzvervielfacher

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EP (1) EP0352961B1 (de)
JP (1) JPH0279330A (de)
DE (1) DE68918021T2 (de)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10145215B2 (en) 2014-12-31 2018-12-04 Halliburton Energy Services, Inc. Drill bit with electrical power generator

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1055780C (zh) * 1993-04-13 2000-08-23 Eev有限公司 电子束管
GB9724960D0 (en) 1997-11-27 1998-01-28 Eev Ltd Electron beam tubes
RU2352015C1 (ru) * 2007-07-23 2009-04-10 Федеральное государственное унитарное предприятие "Научно-производственное предприятие "Торий" Свч-прибор

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
IT1143751B (it) * 1977-08-01 1986-10-22 Sits Soc It Telecom Siemens Klystron oscillatore accordabile
US4527091A (en) * 1983-06-09 1985-07-02 Varian Associates, Inc. Density modulated electron beam tube with enhanced gain

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10145215B2 (en) 2014-12-31 2018-12-04 Halliburton Energy Services, Inc. Drill bit with electrical power generator

Also Published As

Publication number Publication date
JPH0279330A (ja) 1990-03-19
EP0352961A1 (de) 1990-01-31
DE68918021D1 (de) 1994-10-13
DE68918021T2 (de) 1995-01-12

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