Collector for a travelling wave tube and travelling wave tube with such a collector

Abstract

A collector (2) for a traveling-wave tube (70) is described, which has at least two stages and which has an inlet opening (8) for receiving an electron beam, to which a first collector stage (6) is connected, wherein the first collector stage (6) includes a magnetic focusing and a last collector stage (22) is electrostatically designed, wherein a high-voltage connection (18) of the first collector stage (6) is led radially outwards in the region of the first collector stage (6) adjacent to the last collector stage (22) or adjacent to one or more further collector stages (32; 52) via a high-voltage bushing (20), wherein a ceramic insulating shell (26) is immediately adjacent to and free of high-voltage bushings on an outer surface of an electrode (24) of the last collector stage (22).

Description

[0001] The invention relates to a collector for a traveling wave tube and a traveling wave tube with such a collector.

[0002] From US Patent 2007 / 0030058A1, an amplifier is known comprising an electron tube with an axial electron beam, equipped with a cathode and at least two collectors, and at least two DC voltage sources. Each collector is connected to a DC voltage source exhibiting such a potential difference that the potential difference between that collector and the cathode decreases the further the collector is from the cathode. The DC voltage sources are connected to each other at a common point located at the collector whose potential difference to the cathode is smaller, but not zero.

[0003] US 2005 / 0067965A1 refers to amplifier vacuum tubes operating at microwave frequencies. The vacuum tube comprises a pump tube, which creates the vacuum inside the tube; an electron gun, which emits an electron beam inside the tube; and a collector, which directly captures the first part of the electron beam. The pump tube then redirects the second part of the electron beam toward the collector. All electrodes of the collector are connected to a voltage source via laterally mounted terminals.

[0004] WO 2013 / 104637 A1 and DE 10 2012 100 132 A1 describe a collector for a traveling-wave tube and a traveling-wave tube with such a collector. A design is specified in which at least one first collector stage has magnetic beam focusing and a smaller diameter, and at least one further collector stage has a significantly larger diameter than the first collector stage.

[0005] US Patent 6,094,009 A describes a collector for gathering an electron beam in a traveling-wave tube. The collector has an input end for receiving the electron beam from the traveling-wave tube. The collector also has a plurality of stages biased to predetermined voltages and arranged along a common collector axis, but at different axial positions relative to the input end. One stage is biased with a more negative voltage than a subsequent stage located axially farther from the input end, in order to create an electrostatic focusing lens for focusing the electron beam onto subsequent stages, thereby increasing the collector's gathering efficiency.

[0006] German patent DE 698 16 912 T2 discloses a collector for collecting an electron beam in a traveling-wave tube. The collector has an input end for receiving the electron beam from the traveling-wave tube. The collector also has several stages, biased to specific voltages, arranged along a common collector axis and located in different axial positions relative to the input end. One stage is biased with a more negative voltage than a subsequent stage, which is positioned axially farther from the input end, in order to create an electrostatic focusing lens that focuses the electron beam onto subsequent stages and thereby increases the collector's collection efficiency.

[0007] DE 38 77 004 T2 shows an electron collector having four axially symmetrical electrodes with off-axis openings that receive an electron beam. By applying a successively lower voltage to each electrode compared to the cathode that generates the electron beam, an electrostatic field is created that efficiently deflects the beam electrons onto the electrodes where they are collected.

[0008] US Patent 5,780,970 A describes a multi-stage recessed collector for receiving energy from a small, circulating electron beam. This collector uses multiple electrodes with different potentials to sort the individual electrons based on their total energy level. Magnetic field-generating coils and magnetic iron shapers create adiabatic and controlled non-adiabatic transitions of the incident electron beam to further facilitate sorting.

[0009] In DE 1 791 080 B, a system for generating a spatial periodic magnetic field for focusing the electron beam of a high-power klystron is shown by arranging a number of ring-shaped magnetic rings with axial magnetization in the same direction coaxially around the drift tubes between resonance cavities.

[0010] Based on this state of the art, the inventor has now set himself the task of creating a collector or a traveling wave tube with such a collector and improved high-voltage insulation.

[0011] This problem is solved by independent claim 1. Further advantageous embodiments of the invention are the subject of the dependent claims. These can be combined with one another in a technologically meaningful manner. The description, particularly in conjunction with the drawing, further characterizes and specifies the invention described in the claims.

[0012] According to the invention, a collector for a traveling wave tube is provided, comprising at least two stages, which has an inlet opening for receiving an electron beam, to which a first collector stage is connected, wherein the first collector stage comprises a magnetic focusing and a last collector stage is electrostatically designed, wherein a high-voltage connection of the first collector stage is led radially outwards in the region of the first collector stage adjacent to the last collector stage or adjacent to a further collector stage via a high-voltage bushing, wherein a ceramic insulating shell is immediately adjacent to an outer surface of the last collector stage and free of high-voltage bushings.

[0013] According to the invention, a collector with at least two stages is used, which can be operated as a collector in a traveling-wave tube. The first collector stage has magnetic focusing for focusing an electron beam generated in the traveling-wave tube. In this way, it is possible to make the first collector stage more compact compared to an electrostatic collector stage. The space gained in this way is then used to provide a high-voltage feedthrough for supplying power to the first collector stage. The radially outward-facing high-voltage feedthrough has improved insulation properties compared to axial feedthroughs.In this way, it is also possible to install the ceramic insulation shell of the adjacent collector stage, which in the case of a two-stage collector is the last collector stage, without the axially running free space typical in the prior art, which creates a high-voltage supply that is routed to an end of the collector opposite an inlet opening of the electron beam. According to the invention, only the last collector stage is supplied at this end of the collector. Due to the absence of free space in the ceramic insulation shell, the insulation of the high-voltage components of the collector stages from the surrounding ground potential is improved. The term "immediately adjacent" is to be understood here as meaning that there is no free space between the outer surface of the last collector stage and the ceramic insulation shell.Ideally, the ceramic insulation shell rests fully on the last collector stage. This not only improves the insulation of the high-voltage components of the collector stages, but also allows the ceramic insulation shell to have a smaller diameter, resulting in space savings for the traveling wave tube according to the invention.

[0014] According to one embodiment of the invention, the first collector stage has a smaller diameter than the last or one or more further collector stages.

[0015] Magnetic focusing allows for a miniaturization of the first collector stage in several respects. Besides requiring less axial space, the diameter of the first collector stage can also be reduced. Furthermore, magnetic focusing of the electron beam creates an asymmetry between incoming and outgoing electrons, reducing the probability of electrons backflowing from the entrance aperture. This results in higher collector efficiency when used in traveling-wave tubes.

[0016] According to a further embodiment of the invention, a ring magnet is arranged axially displaceable between the opening and the high-voltage connection for magnetic focusing.

[0017] This allows the focusing of the electron beam to be individually adjusted during commissioning.

[0018] According to a further embodiment of the invention, the collector stages are provided at least partially with further ceramic insulating shells and with a metallic outer surface.

[0019] Due to the lack of free space in the ceramic insulation material of the last collector stage, as described above, the collector has a compact structure which, with the addition of a metallic outer surface, exhibits improved thermal properties, as these can be used for heat dissipation.

[0020] According to a further embodiment of the invention, the collector is designed with at least three stages, wherein the high-voltage connections of one or more further collector stages are led radially outwards via high-voltage feedthroughs.

[0021] In this way, a compact design of a multi-stage collector is achieved.

[0022] According to a further embodiment of the invention, the high-voltage connection of the first collector stage and the high-voltage connections of one or more further collector stages are arranged such that they divide a circle conceived in a plane perpendicular to the electron beam into equally sized circular sectors.

[0023] Accordingly, the distance between the live parts is optimized to minimize the risk of voltage jumps.

[0024] According to a further embodiment of the invention, the first collector stage is arranged at an angle relative to the electron beam.

[0025] According to a further embodiment of the invention, the one or more further collector stages are at least partially provided with magnetic focusing. All further collector stages can also be equipped with magnetic focusing.

[0026] The invention is suitable for different configurations of collectors, which may include magnetic or electrostatic further collector stages, also in mixed forms.

[0027] Furthermore, a traveling wave tube is specified, which has an electron beam source, a delay line and a collector, as described above.

[0028] Some exemplary embodiments are explained in more detail below with reference to the drawing. The drawing shows: Figure 1 shows a first embodiment of the invention with a two-stage collector in a sectional view; Figure 2 shows a further embodiment of the invention with a three-stage collector in a sectional view; and Figure 3 shows a further embodiment of the invention with a five-stage collector in a sectional view; Figure 4 shows the embodiment from Figure 3in a schematic top view from an axial direction; and Figure 5 shows an embodiment of a collector according to the invention in a traveling wave tube in a schematic representation.

[0029] In the figures, identical or functionally equivalent components are provided with the same reference symbols.

[0030] In Figure 1A collector 2 is shown in a sectional view. The section plane is arranged along an axial direction 4, which essentially corresponds to the direction of an incoming electron beam. In this embodiment, the collector 2 is designed in two stages. The first collector stage 6 has an inlet opening 8 through which the electron beam can enter the collector 2. In addition to electrodes 10, the first collector stage 6 has a ceramic insulating shell 12, to which a metallic outer shell 14 is attached. A first ring magnet 16 is arranged outside the metallic outer shell 14. The electrodes 10 of the first collector stage 6 are supplied with a high voltage via a high-voltage connection 18, which is guided radially into the interior of the collector 2 through a ceramic bushing 20.

[0031] The design of the second and, in this case, final collector stage 22 differs from that of the first collector stage 6 in that it uses an electrostatic design. The final collector stage 22 has additional electrodes 24, which can be supplied with a high voltage via a further high-voltage connection 30. This additional high-voltage connection 30 is located approximately centrally at one axial end of the collector 2. For insulation, the additional electrode 24 of the final collector stage 22 is surrounded by a ceramic insulating shell 26, to which a further metallic outer shell 28 is attached. This further metallic outer shell 28 can be electrically connected to the metallic outer shell 14.

[0032] The magnetic focusing allows the first collector stage 6 to be designed compactly, thus creating space for the high-voltage connection 18. This can be determined based on the outer diameter of the first collector stage, for example, using the outer diameter of the ceramic insulation shell 12 as a guide. Because the first high-voltage connection 18 is routed radially outwards between the first collector stage 6 and the last collector stage 22, it is not necessary to provide spaces inside the ceramic insulation shell 26, as is the case in the prior art, through which the high-voltage line to the first collector stage would be routed. In this way, both the high-voltage withstand capability of the collector 2 can be increased and the design of the last collector stage 22 can be optimized with regard to its space requirements.

[0033] An asymmetrical design of the field of the first ring magnet 12 improves the efficiency of the collector, as the probability of electrodes being able to return towards an electron beam source decreases. The metallic outer surface 14 and the additional metallic outer surface 28 improve the thermal properties with respect to the heat dissipation of the collector 2.

[0034] The first ring magnet 12 can be moved slightly in the axial direction, so that the focusing of the first collector stage 6 can be individually adjusted during commissioning.

[0035] The in Figure 2 The setup shown corresponds to a three-stage collector. Besides the first collector stage (6) and the last collector stage (22), which, as in Figure 1As depicted, an additional collector stage 32 is provided as a second collector stage, arranged between the first collector stage 6 and the last collector stage 22. This second collector stage 32 features magnetic focusing by means of another ring magnet 34. The second ring magnet 34 is arranged over another metallic outer shell 36, to which a further ceramic insulating shell 38 is attached. This ceramic insulating shell provides electrical insulation to the further electrodes 40 of the second collector stage 32. The first collector stage 6 can have a smaller outer diameter than the second collector stage, which can be determined from the outer diameters of the ceramic insulating shell 12 and the second ceramic insulating shell 38.

[0036] The high-voltage supply to the further electrodes 40 is provided via another high-voltage connection 42, which is routed through a further high-voltage bushing 44 extending radially outwards. This further high-voltage bushing 44 is located between the further ring magnet 34 and the last collector stage 22. Unlike the representation in Figure 2, the first high-voltage bushing 20 and the further high-voltage bushing 44 can be arranged parallel to each other but point in different directions, so that the supply lines can be routed on opposite sides of the collector 2.

[0037] In Figure 3A further embodiment of the collector 2 according to the invention is shown. This collector 2 is designed with five stages. Here, the first collector stage 6 is again designed with magnetic focusing by means of a ring magnet 16, which is preferably movably arranged on the metallic outer surface 14 during commissioning. The high-voltage connection 18 of the first electrode 10 is again led radially outwards adjacent to the ring magnet 16. Here, the high-voltage connection 18 is guided through a further ceramic insulating sheath 50.

[0038] The second to fourth collector stages, which are hereinafter collectively referred to as further collector stages 52, are each electrostatically designed and have further electrodes 54 inside them, which are each connected to further high-voltage connections 56 in the further ceramic insulating shell 50.

[0039] The last collector stage 22 essentially follows the description from Figure 1 and has, immediately adjacent to the further ceramic insulation shell 50, the further metallic outer surface 28, the ceramic insulation shell 26 and the last collector electrode 24, which is connected to the high voltage connection 30.

[0040] As in Figure 4As shown, the additional high-voltage connections 56, together with the first high-voltage connection 18, can be arranged spatially such that their distance from each other is maximized. In a plane perpendicular to the axial direction 4, the high-voltage connections 56 and 18 would be arranged on an imaginary circle 60, which is divided by them into equal circular sectors. Such an arrangement can, of course, also be created with a different number of high-voltage connections, whereby the imaginary circle 60 is not divided into 90° sectors, but, for example, into 120° sectors for a four-stage collector or 180° sectors for a three-stage collector.

[0041] In Figure 5The collector 2 according to the invention is shown in a traveling-wave tube 70. The traveling-wave tube 70 has an electron source 72 to which a delay line 74 is connected. The collector 2 is arranged at the end of the delay line 74. An input signal can be supplied via a high-frequency connection 76, which leaves the traveling-wave tube as an output signal via the further high-frequency connection 78.

[0042] As described in the previous embodiments, the invention can be used with differently configured collector arrangements. A common feature is that the first stage has magnetic focusing and, in the last, electrostatically designed stage, no high-voltage lines from previous stages are routed along the outside.

[0043] The features specified above and in the claims, as well as those discernible from the illustrations, can be advantageously implemented both individually and in various combinations. The invention is not limited to the described embodiments but can be modified in many ways within the scope of expert knowledge. List of reference symbols:

[0044] 2 Collector 4 Axial direction 6 First collector stage 8 Inlet opening 10 First electrode 12 Insulation sleeve 14 Outer surface 16 Ring magnet 18 First high-voltage connection 20 First high-voltage bushing 22 Further collector stage 24 Further electrode 26 Further insulation sleeve 28 Further outer surface 30 Further high-voltage connection 32 Further collector stage 34 Further ring magnet 36 Further outer shell 38 Further insulation sleeve 40 Further electrodes 42 Further high-voltage connection 44 Further high-voltage bushing 50 Further insulation sleeve 52 Further collector stages 54 Further electrodes 56 Further high-voltage connections 60 Circuit 70 Traveling field tube 72 Electron source 74 Delay line 76 High-frequency connection 78 High-frequency connection

Claims

1. Collector (2) for a traveling wave tube (70), comprising at least two stages and having an inlet opening (8) for receiving an electron beam, to which a first collector stage (6) is connected, wherein the first collector stage (6) comprises a magnetic focusing and a last collector stage (22) is electrostatically designed, wherein a high-voltage connection (18) of the first collector stage (6) is led radially outwards in the region of the first collector stage (6) adjacent to the last collector stage (22) or adjacent to one or more further collector stages (32; 52) via a high-voltage bushing (20), wherein a ceramic insulating shell (26) is immediately adjacent to and free of high-voltage bushings on an outer surface of an electrode (24) of the last collector stage (22).

2. Collector according to claim 1, wherein the first collector stage (6) has a smaller outer diameter on a further ceramic insulating shell (12) than the last or one or more further collector stages (22; 32; 52).

3. Collector according to claim 1 or 2, in which a ring magnet (16) is arranged axially displaceably between the inlet opening (8) and the high-voltage connection (18) for magnetic focusing.

4. Collector according to one of claims 1 to 3, wherein the collector stages are provided at least sectionally with further ceramic insulating shells (12; 38; 50) and with a metallic outer surface (14) or a further metallic outer surface (28; 36).

5. Collector according to one of claims 1 to 4, which is designed in at least three stages, wherein the high-voltage connections (42; 56) of the one or more further collector stages (32; 52) are guided radially outwards via high-voltage feedthroughs.

6. Collector according to claim 5, wherein the high-voltage connection (18) of the first collector stage and the high-voltage connections (42; 56) of one or more further collector stages are arranged such that they divide a circle (60) conceived in a plane perpendicular to the electron beam into equally sized circular sectors.

7. Collector according to one of claims 1 to 6, wherein the one or more further collector stages (32) are at least partially provided with a magnetic focusing.

8. Collector according to one of claims 1 to 6, wherein the one or more further collector stages (32) are at least partially provided with an electrostatic focusing.

9. Collector according to claims 7 and 8, wherein either all further collector stages are designed with magnetic focusing or all further collector stages are designed with electrostatic focusing.

10. Traveling wave tube (70) comprising an electron beam source (72), a delay line (74) and a collector (2) according to any one of claims 1 to 9.

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