Classifications

• • 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
  • H01J23/20—Cavity resonators; Adjustment or tuning thereof
  • H01J23/207—Tuning of single resonator

Definitions

• the invention relates to a microwave tube with mechanical frequency tuning.
• the invention finds a particularly advantageous application in the field of electronic tubes making it possible to generate and / or amplify radioelectric signals.
• the principle of a microwave tube according to the prior art is shown in Figure 1.
• the microwave tube comprises: an electron source consisting of an emission cathode K and an electron gun of anodes CA to form an electron beam F, a focusing coil L producing a continuous axial magnetic field B bathing the electron beam so as to avoid its expansion by mutual repulsion between electrons, - a microwave structure H placed near the beam and. capable of generating, propagating and amplifying an electromagnetic wave, and a collector C to collect the electrons after interaction with the wave.
• TOP traveling wave tubes
• BO type tubes Back Ward Oscillator
• klystrons magnetrons
• carcinotrons masers etc.
• a BWO type tube comprises an insert I and a periodic structure P.
• a distance d defines the period of the periodic structure.
• a BWO type microwave tube is optimized for a single frequency F. It is therefore only effective in a very narrow frequency band ⁇ F, and all the more narrower when the output power is large (typically ⁇ F / F ⁇ 5%).
• the microwave tubes mentioned above are optimized to work at a fixed frequency and the known means for varying the frequency of the tube always lead to a significant deterioration in the performance of the tube. The invention does not have this drawback.
• the invention relates to a microwave tube for generating an electromagnetic wave of frequency F, characterized in that it comprises mechanical means for varying the frequency F consisting of a set of rings defining a periodic structure inside the tube, and mechanical means for moving the rings relative to each other while maintaining a periodicity in the periodic structure during the movement of the rings.
• the mechanical means for moving the rings comprise a set of electrical contacts between the rings, at least one lead screw, a set of nuts mounted on the lead screw, a set of rods, each rod securely connecting a nut to a ring, the tube being provided with at least one slot allowing the passage of rods in the wall of the tube, the lead screw comprising several sectors of different pitches capable of maintaining a periodicity between the rings during 'a rotation of the mother screw.
• mechanical means for moving the rings comprise a set of electrical contacts between the rings, at least one assembly of pins, each pin being fixedly connected to a ring, the tube being provided at least one longitudinal slot allowing the passage of the lugs in the wall of the tube, an outer ring to the tube comprising at least one set of slots, each slot of the outer ring allowing the passage of at least one lug, the slots d 'a set of slots having a different inclination for each ring to maintain a periodicity to the different rings when moving the rings.
• the mechanical means for varying the frequency F therefore comprise at least one longitudinal slot made in the tube and allowing the passage of drive means for all of the rings.
• the microwave tube according to the invention is a TOP, a tube of the BWO type, a klystron, a magnetron, a carcinatron or a maser.
• the periodic structure of the microwave tube is made of corrugated sheet.
• the invention has the advantage of being able to vary the frequency F of the electromagnetic wave emitted over a wide range of variation, namely several tens of percent, while retaining the amplification performance of the electromagnetic wave existing in power sources working at fixed frequency.
• the invention advantageously applies to any source of radioelectric power consisting of an electron beam circulating through a structure comprising periodic or non-periodic variations in shape.
• the integrated source according to the invention comprises a periodic wavy geometric structure which makes it possible to obtain a frequency variation by a mechanical process allowing either a modification of the pitch of the periodic structure constituted, for example, of corrugated sheet, or a variation of the length of an insert, or a combination of the two structures.
• This integrated system advantageously allows rapid modulation of the parameters that are the frequency and the power of the radiofrequency signal.
• the system is easily automated and able to be controlled quickly from the outside, without having to modify the operation of the electron beam.
• This integrated system is particularly well suited to BWO type microwave tubes. It then replaces the periodic structures in place and / or the inserts. It is also easily adaptable to other types of tubes. It can also be combined with other systems designed to allow variation of the signal output frequency. It then advantageously makes it possible to increase the efficiency and the operating range of the system.
• the frequency radiated by a tube according to the invention can advantageously be chosen within a significant range, for example several tens of%, without collapse of the output power, the other parameters of the tube (such as, for example, the voltage and the current of the electron beam) not being modified.
• FIG. 1 represents a principle diagram of microwave tube according to known art
• FIG. 2 represents a block diagram of a BWO tube according to known art
• - Figures 3A and 3B show a first embodiment of microwave tube according to the invention
• Figures 4A and 4B show a second embodiment of microwave tube according to the invention.
• a first embodiment of the invention is shown in Figures 3A and 3B.
• the electromechanical structure for adjusting the frequency of the microwave tube comprises a fixed part and a mobile part.
• the fixed part consists of the longitudinal wall 3 of the tube in which is formed at least one guide slot G.
• the mobile part comprises: at least one mother screw 4, nuts 5 mounted on the mother screw 4, a set of rods 6 and a set of rings (for example four rings A, B, C, D), each rod 6 securely connecting a nut to a ring, the rings being mounted inside the wall 3 of the tube, electrical contacts 2 between the rings.
• the guide slot (s) G allow the rods 6 to pass through the longitudinal wall 3 of the tube in order to connect the nuts 5 to the rings.
• a ring seen in section (cf. figures) is, for example, profiled like a ja te.
• the lead screw When adjusting the frequency, the lead screw is rotated, which drives the nuts 5, the rods 6, the rings A, B, C, D and the electrical contacts 2 in a translational movement.
• the ring A can be connected to a mechanical part p which can then slide in the tube 3.
• the mother screw 4 is in one piece. It consists of several different threading areas adapted to each of the nuts 5.
• a single lead screw is theoretically sufficient for the implementation of the invention.
• FIG. 3A illustrates the case where the device comprises two lead screws. The second screw, when used, must then rotate in perfect synchronism with the first mother screw. The quality of the translation of the rings is thereby improved due to the symmetrization of the points of application of the movement.
• a lead screw has several sectors of different pitch to keep the system, during the rotation of the lead screw, the same distance between the vertices of the periodic corrugated structure that constitute the rings.
• L (AB) be the distance between rings A and B
• L (BC) the distance between rings B and C
• L (CD) the distance between rings C and D.
• Figures 4A and 4B show a second embodiment of the invention.
• the variation in the periodicity of the rings is based on the rotation of a ring fitted with slots inside which pins can be moved connected to the periodic corrugated structures.
• the inclination of these slots is such that it makes it possible to maintain a periodicity.
• the tube 3 is the same as that of the previous assembly.
• Each ring placed inside the tube 3 is integral with a lug 7.
• a lug 7 moves inside two slots located on two independent parts, namely the fixed tube 3 and an outer ring 8.
• a first slot 9 placed on the fixed tube 3 only authorizes translational movements of the rings in the longitudinal direction of the tube.
• a set of slots 10, placed on the outer ring 8, make it possible to fix the extent of the variations in the period of the periodic structure.
• the slots 10 correspond to the different pitches of the mother screw 4 of the assembly previous and performs the same function.
• the slots 10 have a different inclination for each ring in order to maintain, when the rings are moved, a periodicity for the different rings.
• the outer ring 8 can therefore here be assimilated to a set of screw-mother / nut pairs of the device according to the first embodiment of the invention.
• the tube 3 comprises only a single longitudinal slot 9 and the outer ring 8 comprises only a single set of slots 10.
• the invention also relates to the case where the tube 3 comprises, for example, two longitudinal slots 9, the two longitudinal slots then being arranged symmetrically on the tube 3, and where the outer ring then comprises two sets of slots 10, the second set of slots 10 being associated with the second longitudinal slot for moving the rings according to the principle of the invention.
• the mechanism according to the invention can be automated, can be controlled quickly from the outside and at will without modifying the operation of the electron beam.
• the microwave tube can also include an insert whose length can be adjusted. Such an adjustment is implemented by the displacement of a second tube in the tube 3, with conservation of the electrical continuity. This improvement is not used per se to vary the frequency of the tube. It can allow, for example, to adapt the total length of the tube (insert + periodic structure) to variations in length of the periodic structure.

Landscapes

• Microwave Tubes (AREA)
• Constitution Of High-Frequency Heating (AREA)
• Surgical Instruments (AREA)
• Making Paper Articles (AREA)
• Developing Agents For Electrophotography (AREA)
• Length-Measuring Devices Using Wave Or Particle Radiation (AREA)
• Control Of Motors That Do Not Use Commutators (AREA)

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• 2002
  • 2002-06-25 FR FR0207849A patent/FR2841379B1/fr not_active Expired - Fee Related
• 2003
  • 2003-06-25 US US10/519,611 patent/US7456577B2/en not_active Expired - Fee Related
  • 2003-06-25 WO PCT/FR2003/001960 patent/WO2004001787A2/fr not_active Ceased
  • 2003-06-25 EP EP03760787A patent/EP1579469B1/de not_active Expired - Lifetime
  • 2003-06-25 AT AT03760787T patent/ATE519217T1/de not_active IP Right Cessation

Non-Patent Citations (1)

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