Classifications

• • 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
  • H01J25/06—Tubes having only one resonator, without reflection of the electron stream, and in which the modulation produced in the modulator zone is mainly velocity modulation, e.g. Lüdi-Klystron
• • 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
  • H01J23/09—Electric systems for directing or deflecting the discharge along a desired path, e.g. E-type
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J2225/00—Transit-time tubes, e.g. Klystrons, travelling-wave tubes, magnetrons
  • H01J2225/02—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
  • H01J2225/10—Klystrons, i.e. tubes having two or more resonators, without reflection of the electron stream, and in which the stream is modulated mainly by velocity in the zone of the input resonator
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J2225/00—Transit-time tubes, e.g. Klystrons, travelling-wave tubes, magnetrons
  • H01J2225/34—Travelling-wave tubes; Tubes in which a travelling wave is simulated at spaced gaps
  • H01J2225/36—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

Definitions

• the present invention relates to multi-beam longitudinal interaction electronic tubes such as, for example, klystrons or traveling wave tubes.
• These tubes generally constructed around an axis have several longitudinal electron beams parallel to this axis. These beams are often produced by a common electron gun, equipped with several cathodes and are collected at the end of the race in one or more collectors. Between the barrel and the collector, they pass through a body which is a microwave structure at the exit of which is extracted microwave energy. This structure can be formed of a succession of resonant cavities and sliding tubes.
• the electron beams to keep their long and fine shape, are focused by the magnetic field of a focusing centered on the main axis and which surrounds the microwave structure.
• the advantages of multi-beam electronic tubes are as follows: the current produced is higher and / or the high voltage and the length are shorter.
• the size of the tube is generally reduced.
• the power supply and the modulator used are thus simplified and more compact.
• the interaction efficiency is better due to the generally lower perveance of each of the beams.
• the bandwidth is widened due to the fact that the cavities are charged with a higher current.
• One of the main drawbacks compared to single-beam tubes is that it is difficult to generate an optimum focusing magnetic field which allows the beams to circulate in the microwave structure without notable interception by the sliding tubes.
• the intercepted current In multi-beam klystrons the intercepted current, called body current, is often of the order of 4 to 8% whereas it does not exceed 2 to 3% in conventional single-beam klystrons even when the beam is strongly modulated at high frequency such as this is the case with high yielding klystrons. Too much interception leads not only to a prohibitive heating requiring a complex and expensive cooling system but also to a malfunction of the tube because it can occur expansion, degassing, frequency changes, oscillations, excitations of parasitic modes, reflected electrons, ion bombardments and a disturbed interaction between the beam and the microwave structure.
• each beam creates an azimuthal magnetic field which, depending on the configuration of the tube and its operating mode, may disturb the other beams.
• This azimuthal magnetic field is reflected, at the offset axes, by a centrifugal radial force which deflects them.
• Improvements can also be made at the level of the barrel so that the magnetic flux lines substantially follow the trajectory of the electrons as soon as they are emitted.
• One can also act on the inclination of the sliding tubes so that they follow the general movement of the beams.
• the present invention therefore aims to reduce or even cancel this induced azimuthal magnetic field without degrading the gain or yield characteristics.
• the present invention provides a multibeam electronic tube comprising several substantially parallel electron beams passing through a body. Among these beams, at least some, delimit an inter-beam volume. Each of the beams delimiting the inter-beam volume is subjected to a disturbing azimuthal magnetic field induced by all the others.
• the tube comprises, at the level of the body, means allowing, in at least one conductive element located in the inter-beam volume, a circulation of a counter-current in a direction opposite to that of the current of the beams, this counter-current generating at level of the beams delimiting the inter-beam volume, a magnetic field of correction which opposes the disturbing magnetic field.
• the conductive element can be integrated into the body or, on the contrary, electrically isolated from the body.
• the means allowing the circulation of the counter-current in the conductive element integrated into the body may include a ground connection, near the entry of the body, so that the counter-current comes from the current of the beams which closes by this ground, the collector being at an intermediate potential between that of cathodes producing the beams and ground.
• this ground connection will be connected to a high voltage power supply which delivers the potential to the cathodes.
• the body has a succession of cavities and at the input and output of the cavities, the beams are contained in sliding tubes.
• this conductive block serves as a conductive element in which the counter-current flows.
• the conductive block may have a resistance, in a central part including the inter-beam volume, smaller than that possessed by a peripheral part of the block, situated around the central part.
• the central part can be made of a first material and the peripheral part of a second material, the second material having the greatest resistance.
• a resistive insert can be included in the conductive block and the common wall, this resistive insert forces the counter current to circulate in the conductive block in a loop around the insert and in the common wall on either side of the insert in opposite directions.
• the means allowing the circulation of the counter-current may comprise a first connection means near the inlet of the body and a second connection means near the outlet of the body, these connection means being intended to be connected to a power supply. having to deliver the counter current.
• the conductive element In the configuration where the conductive element is integrated into the body, the latter and / or the collector must be electrically isolated from various members with which they are usually in electrical contact.
• the inter-beam volume is hollow at the level of the sliding tubes and it is possible to accommodate the conducting element therein substantially parallel to the sliding tubes and without electrical contact with the body.
• This conductive element may comprise a rigid section at the inlet and at the outlet of a cavity and a flexible connection which spans a cavity by connecting two rigid sections situated on either side of the cavity.
• FIG. 1 a in cross section, the body of a multibeam tube according to the invention
• FIG. 2 a longitudinal section of a multibeam klystron according to the invention
• FIGS. 3a, 3b partial longitudinal and transverse sections of the body of a klystron according to the invention with a conductive element integrated into the body,
• FIGS. 4a, 4b partial longitudinal and transverse sections of another variant of another of a klystron according to the invention, with a conductive element integrated into the body,
• FIGS. 5a, 5b, 5c of partial longitudinal and transverse sections of the klystron body according to the invention with conductive elements isolated from the body,
• Figure 1a shows in cross section, the electron beams 1-7 of a multibeam tube. These substantially parallel beams are each contained in a sliding tube 13 at the level of the section. These sliding tubes 13 are hollowed out in the same conductive block 15 which forms part of the body 10 of the tube.
• One of these beams 1 is centered on a central axis, perpendicular to the sheet, passing at point 0.
• the other beams 2 to 7, arranged on a circle centered at 0, are offset. They are conventionally substantially equidistant from each other.
• At least one offset beam 7 of the tube of FIG. 1a is therefore subjected on the one hand to its own field bg7 which generates a non-deviant centripetal focusing force and to the resultant B ⁇ of the fields bel, b ⁇ 2, b ⁇ 3, b ⁇ 4, b ⁇ 5, be6 induced by all the other beams 1 to 6.
• FIG. 2 shows a multibeam tube according to the invention.
• This tube is a multibeam klystron. It is built around an axis XX '.
• the tube has several beams numbered from 1 to 7 arranged like those of FIG. 1a to which we also refer.
• these seven beams six referenced from 2 to 7 delimit an inter-beam volume 22.
• they are placed on a circle of radius a and the inter-beam volume 22 is cylindrical.
• the last beam 1 is centered on the axis XX ', the others are offset.
• the beams 1 to 7 are produced by a barrel 17, they then enter a body 10 which they pass through and at its outlet S are collected in a collector 11.
• the barrel 17 has seven cathodes 18 which produce the beams 1 to 7 when '' they are brought to an appropriate VK potential delivered by a high voltage A1 supply. It also includes an anode 16 which accelerates the electrons towards the entry E of the body 10. It is brought to a less negative potential than that VK of the cathodes. In Figure 2, only three cathodes are visible.
• the body 10 is formed by alternating cavities 20 and sliding tubes 13.
• the cavities 20 have side walls 27.
• the beams 1 to 7 are contained in the sliding tubes 13 before entering the first cavity 20, leaving the last cavity 20 and more generally between each cavity 20.
• the body 10 is placed in a tubular focusing device 12.
• the body 10 begins after an input pole piece 19.1 and ends before an output pole piece 19.2.
• the multibeam electronic tube according to the invention comprises, at level of the body 10, means M allowing, in at least one conductive element 23 located in the interbeam volume 22, a circulation of a counter-current I 'in the opposite direction from the current I carried by all the beams.
• the conductive element 23 is integrated into the body 10 of the tube and the means M allowing the circulation of the counter current I 'comprise a ground connection P, near the entry E of the body 10, so that the counter current I 'comes from the current I carried by all the beams which closes with this mass.
• the collector 11 is naturally at a potential VQ intermediate between that V of the cathodes 18 and the ground.
• the conducting block 15 shown is a cylinder of radius a + g + t with g radius of a sliding tube and t thickness of material located between the sliding tubes 13 and the edge of the block 15. This thickness t contributes to sealing inside the body 10.
• the counter-current I ' circulates throughout the body 10 in the opposite direction to the current I of the beams 1-7 but only the part which circulates inside the inter-beam space 22 provides a correction.
• the part circulating outside the inter-beam volume 22, in particular in the side walls 27 of the cavities, does not participate in the correction but does not induce disturbance.
• the ground connection P is located at the level of the anode 16 of the barrel 17. It can be envisaged to bring it to the level of the input pole piece 19.1. This input pole piece 19.1 prevents the cathodes 18 from being disturbed by the magnetic field of the focusing device 12.
• the potential VK of the cathodes 18 is delivered by the supply A1 which is connected between the cathodes 18 and the ground connection P.
• Circulating the counter current I 'in a conductive element 23 integrated into the body 10 of the tube now requires electrical insulation of this body 10 and / or of the collector 11 with respect to other organs of the tube with which they were in electrical contact in the conventional configurations of the prior art.
• These include the focusing device 12 which will be electrically isolated from the body 10 using dielectric material 24.1.
• the insulation is done by means of the pole pieces 19.1, 19.2 of entry and exit.
• These pole pieces 19.1, 19.2 are in conventional tubes in contact with the body at its inlet E and at its outlet S.
• a sheet 24.1 of teflon inserted between the focusing device 12 and the pole pieces 19.1, 19.2 will be used. They are also transmission guides, located at the level of the extreme cavities.
• An input waveguide 25.1 is connected to the first cavity 20 and allows a signal to be amplified to be injected there.
• This waveguide 25 is electrically isolated from the body 10 using an insulating flange 24.2.
• the last cavity 20 communicates with an output waveguide 25.2, intended for the transmission of the microwave energy produced by the tube to a user member (not shown).
• This waveguide 25.2 is electrically isolated from the body 10 using an insulating flange 24.2.
• a cooling device 26 is provided around the manifold 11 and even possibly of the body 10.
• This cooling device 26 will be electrically isolated from the manifold 11 and if necessary from the body 10.
• This insulation can be obtained by making the cooling device with dielectric materials, for example at least one conduit 28 made of plastic material in which a resistant cooling fluid circulates. As coolant deionized water can be used.
• the azimuthal magnetic field induced on one of the beams delimiting the inter-beam space 22, by the other beams is worth: 051
• B n ⁇ n - 1 - if the beams delimiting the inter-beam space are ⁇ u 2 ⁇ a arranged on a circle of radius a.
• FIGS. 3a, 3b, 4a, 4b show in longitudinal and transverse section a portion of the body 10 of a multibeam klystron according to the invention in which the circulation of current in the interbeam volume is promoted in two different ways.
• FIG. 3a Two successive cavities 20 are shown diagrammatically in FIG. 3a. They are not shown in Figure 4a for simplicity.
• the cross sections of Figures 3b, 4b are made along the cutting plane aa.
• the conductive blocks 15 are formed by a central part 31 surrounded by a peripheral part 32.
• the sliding tubes 13 are located in the central part 31.
• the limit of the inter-beam volume 22 corresponds substantially to the circle , in dotted lines in FIG. 3b, passing through the center of the sliding tubes 13 and the central part 31 includes the inter-beam volume 22.
• the central part 31 in a first material and the peripheral part 32 in a second material By making for at least one of the blocks, the central part 31 in a first material and the peripheral part 32 in a second material and choosing these materials so that the resistivity of the first material is lower than that of the second material, this preferential circulation in the interfaiseau volume 22.
• the central part 31 can for example be made based on copper and the peripheral part based on stainless steel. Other choices are possible.
• the choice of material of the peripheral part 32 must be compatible with the desired seal.
• Another solution for increasing the resistivity at the periphery of at least one block 15 relative to that in the interfaiseau volume is to cut baffles 33 at the periphery of the block 15. These baffles 33 are illustrated in FIGS. 4a, 4b. This configuration with baffles can be combined with that described in Figures 3a, 3b as Figures 4 show but it is not necessary.
• the means M allowing the circulation of the counter current I' comprise two connection means C1, C2, one near the entry E of the body 10 and the other near its output S, these connection means being intended to be connected to the terminals of a low voltage supply A2 having to deliver the counter current I '.
• Figure 6 shows this characteristic applied to a multibeam traveling wave tube. It is of course applicable to multibeam klystrons. In the multibeam klystrons described, there is a compensation for the trajectory of the beams where the counter-current circulates inside the inter-beam volume, that is to say at the level of the sliding tubes 13.
• slip 13 occupy about 75% of the length of the body 10 which means that only 25% of the length of the beams does not receive correction but this is not a problem.
• a suitable correction at the input and output of the cavities 20 can be envisaged if necessary to reduce this harmful defocusing effect.
• the interbeam volume 22 is not not full of conductive material.
• Figures 5a, 5b show in partial longitudinal and transverse sections, a multibeam klystron body with this characteristic.
• the conductive element 23 in which the counter current circulates I ' is electrically insulated and distinct from the body 10. It extends in the inter-beam volume 22, parallel to the sliding tubes 13, without electrical contact with them or with the cavities 20. It can be formed of rigid conductive sections 34 located at the inlet and outlet of the cavities, these sections being able to be rigid conductive rods sheathed with insulator 37 such as alumina.
• the flexible connections 35 may be metallic braid sheathed with insulation.
• the means M allowing the circulation of the counter-current I 'comprise at the two ends of the conductive element 23 connection means C1, C2 intended to be connected to a supply A2 having to deliver the counter-current I'.
• the tube does not have a central beam as illustrated in FIG. 5c, a single conductive element 23 suffices in the center, if the tube has a central beam as illustrated in FIG. 5b, several are desirable, arranged between the central beam 1 and the beams 2-7 delimiting the inter-beam volume 22.
• the harmful magnetic field induced at one of the beams by the others appears in the tube only when it operates in continuous mode or with relatively long pulse durations. This is the case for many tubes used in telecommunications, industrial, scientific, and even radar applications.
• the thickness e of material which the disturbing induced magnetic field can pass through is given by:
• the repetition frequency F is 17 Hz maximum, which amounts to saying that the pulses can only last 30 to 40 ms without defocusing effect.
• a multibeam tube according to the invention could also be of the traveling wave tube type as illustrated in FIG. 6.
• the body 10 is formed by a succession of cavities 30 coupled to each other by irises 21 placed on a common wall 36.
• the beams 1 to 7 are contained in sliding tubes 13 before penetrating in the first cavity 30, leaving the last cavity 30 and more generally between the cavities 30. But now the sliding tubes 13 occupy less than 50% of the length of the body 10, which means that the correction obtained is less effective but still interesting.
• the conducting blocks in which the sliding tubes 13 are hollowed are marked with the reference 15 and the common walls 36 are integral with the conducting blocks 15.
• the first part 201 placed in the conductive blocks 15 has the form of a tubular element, it surrounds the sliding tubes 13.
• the second part 202 extends from the first part 201 in the thickness of the common wall 36 like a flange.
• the counter current I ' circulates in the common wall 36 on either side of the second part 202 in opposite directions.
• an insert 200 has the shape of a T whose leg is the second part 202 and whose transverse bar is the first part 201.
• the circulation of the counter current I 'which bypasses the insert 200 is seen in detail on the circled zoom in FIG. 6.
• These inserts 200 can be made, for example from stainless steel, from alumina or even be recesses.
• the means M allowing the circulation of the counter current I ' comprise two connection means C1, C2 one near the entry E of the body 10 and the other C2 near the exit S of the body, these means of connection C1, C2 being intended to be connected to the terminals e1, e2 of a low-voltage supply A2 having to deliver the counter current I '.
• the first connection means C1 is located at the input pole piece 19.1 and the second connection means C2 is located at the base of the manifold 11.
• the first connection means C1 could be on the anode 16 and the second on the output pole piece.
• the second connection means C2 is brought to ground, but other potentials could be envisaged.
• a resistor R suitably chosen in series with the low voltage supply A2 makes it possible to adjust the value of the counter current.
• another supply A1 is shown. It is connected between the cathodes 18 and the collector 11 and is used to create the beams 1 to 7. It is a high voltage supply.
• the multibeam tubes according to the invention do not have a modified structure compared to existing tubes, it suffices to provide the connections described.

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• 1998
  • 1998-07-03 FR FR9808552A patent/FR2780809B1/fr not_active Expired - Fee Related
• 1999
  • 1999-07-02 DE DE69925125T patent/DE69925125D1/de not_active Expired - Lifetime
  • 1999-07-02 CN CN99808226A patent/CN1308769A/zh active Pending
  • 1999-07-02 US US09/720,811 patent/US6486605B1/en not_active Expired - Lifetime
  • 1999-07-02 WO PCT/FR1999/001595 patent/WO2000002226A1/fr active IP Right Grant
  • 1999-07-02 KR KR1020017000062A patent/KR100593845B1/ko not_active IP Right Cessation
  • 1999-07-02 EP EP99929381A patent/EP1095390B1/de not_active Expired - Lifetime
  • 1999-07-02 JP JP2000558534A patent/JP4405674B2/ja not_active Expired - Fee Related

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