DE102012100132A1 - Auffänger for a traveling wave tube and traveling wave tube with such a catcher - Google Patents

Abstract

For a on only one traveling wave tube and for a traveling wave tube with such a catcher, a construction is given in which at least one first catcher stage has a magnetic beam and a smaller diameter and at least one further catcher stage is formed with respect to the first catcher stage substantially larger diameter.

Description

The invention relates to a catcher for a traveling wave tube and a traveling wave tube with such a catcher.

In traveling-wave tubes, a tightly collimated beam of accelerated electrons is generated in an electron beam source and guided along a delay line through a magnetic field. The electrons of the electron beam leaving the delay line are trapped in a collector, often referred to as a collector, to at least partially recover the residual energy of the electrons and at the same time prevent the return of electrons through the delay line. The interceptor is usually designed in multiple stages with interceptor stages located at different electrical potentials in order to take into account the broad velocity distribution of the beam which occurs due to the interaction of the electron beam with a high-frequency signal on the delay line at the output of the delay line.

In principle, purely electrostatic collectors and collectors with magnetic beam guidance are customary for the multistage collector. In the case of electrostatic collectors, after the magnetic field of the delay line has left the electron beam, rapid beam expansion occurs, in particular due to electrostatic repulsive forces between the electrons. In the electrostatic multistage Auffängern such. B. from the EP 0 276 090 B1 or the DE 698 04 954 T2 As is known, the electrodes of the successive catcher stages in the direction of the longitudinal axis have only small axial distances. The pot-shaped closed last electrode typically has a greater axial length.

In the case of the magnetic beam guidance collectors, the catcher stages are of longer construction length but are designed with smaller diameter ring magnets surrounding the collector stages. A magnetically focused collector is z. In "Technical Tubes" by J. Bretting, 1991, ISBN 3-7785-1645-0, on page 177 shown. A similar collector construction is in the DE 60225412 T2 displayed.

When the electrons strike the electrodes of the catcher stages, heat is lost in the electrodes which has to be dissipated to the outside to form a vacuum-tight housing surrounding the several catcher stages. The removal of the heat loss is typically carried out via electrically insulating distance arrangements between metallic inner wall surfaces of the housing and to these substantially parallel electrode shell surfaces of the electrodes. The distance arrangements may in particular be designed as one or more ceramic rings, the outer surfaces of the inner wall of the housing and the inner surfaces of the outer surfaces of the electrodes abut, such. B. in the DE 698 04 954 T2 or the DE 602 25 412 T2 described. For a good heat dissipation large contact surfaces are advantageous.

There are also known combinations of electrostatically focused scavengers with magnet arrangements. So z. B. in the US 4,096,409 arranged an additional ring magnet for beam focusing on the longitudinal axis in front of the inlet opening of the first stage. The first electrode is made of iron and magnetically shields the interior of the collector from the ring magnet.

In the US 6094009 an embodiment of an electrostatic collector is described in which a particular electrostatic field lens is created by special potential adjustment of a middle stage, in order to reduce a return of electrons to the first stages and thus to increase the collector efficiency. A magnet arrangement before and at the first stages is intended to improve the transmission of electrons to subsequent stages past the electrodes of the first stages. The electrodes are radially extendable up to a circular cylindrical common ceramic shell and lie with electrode shell surfaces on the inner wall.

At one of the US 5780970 known collector for the hollow beam of a gyrotron is formed between a conical center electrode and a plurality of annular further electrodes, a widening annular channel. A magnetic field of a magnet arrangement arranged outside the catcher shell and inside the center electrode carries the electrons of the hollow beam in the widening ring channel.

The performance of a traveling-wave tube is largely determined by the thermal load capacity of the electrodes of the collector and the efficiency of the collector in terms of the lowest possible heat generation and a low rate of returning electrons. The heat dissipation from the electrodes to the catcher housing is particularly advantageously achievable via insulating ceramic rings located radially between the housing and essentially circular-cylindrical electrode jacket surfaces of the electrodes with surface heat contact to the housing and to the electrode jacket surfaces.

The present invention has for its object to provide a further improved Auffänger for a traveling wave tube and a traveling wave tube with such a catcher.

Solutions according to the invention are described in the independent claims. The dependent claims contain advantageous refinements and developments of the invention.

It turns out, surprisingly, that the construction according to the invention of a collector for a traveling-wave tube can still achieve a significant increase in the rated output of a traveling-wave tube with the same structural design compared with the tried-and-tested collectors based on the electrostatic principle and the collectors with magnetic beam bundling.

In the construction of a catcher according to the invention, in particular for the first of the plurality of catcher stages advantageously a smaller inner diameter and outer diameter of the spacer assembly and an advantageously large overall length and for at least one further, from the beam inlet opening of the catcher farther Auffängerstufe a relation to the first Auffängerstufe larger indoor and Outer diameter of the distance arrangements, in particular also the diameter of the electrode jacket surfaces of the catcher stages respectively associated electrodes.

The radial thicknesses of the spacer arrangements, which are preferably designed as ceramic rings with respect to the longitudinal axis, are advantageously dimensioned essentially to small thicknesses with the required electrical insulation and the mechanical stability. The ceramic rings may also have uniform thicknesses for different tensions of the individual catcher stages. In the following, without limiting the generality, a substantially uniform radial thickness of ceramic rings used as distance arrangements is assumed. Instead of circumferentially closed ceramic rings can also be provided a plurality of distributed around the circumference of the inner wall of the catcher shell, the mechanical fixation, the electrical insulation and the heat transfer absorbing spacer body can be provided.

A small diameter of the electrode shell surface of the first catcher stage proves to be advantageous for the discharge of the heat input concentrated in this catcher stage, particularly close to the longitudinal axis, by the impact of electrons on the electrode surrounding a narrow opening. Advantageously, for the first catcher stage, the inner diameter of the spacer arrangement, which is considered to be substantially equal to the diameter of the electrode shell surface, not more than 200%, in particular not more than 150% of the axial extent of the contact surface of the spacer assembly and electrode shell surface. Due to the small inner diameter of the spacer arrangement, the heat loss occurring near the electrode opening can flow off quickly to the electrode jacket surface and be discharged there via the ceramic ring to the outer shell of the collector. The small diameter of the electrode sheath surface allows a corresponding small outer diameter of the ceramic ring and correspondingly a small outer diameter of the Auffängerhülle, which is advantageous for the magnetic arrangement in the region of this level beam bundling effective magnetic field strength near the longitudinal axis. The magnet arrangement is preferably formed by at least one ring magnet around the housing.

Due to the beam bundling by means of the magnet arrangement, the distance to the next catcher stage in the longitudinal axis can be selected to be substantially greater in the longitudinal direction than in the case of a first electrode of a purely electrostatic collector. The larger distance to the electrode of the next Auffängerstufe in turn advantageously allows a large axial dimension of the contact surface of the electrode shell surface and the adjoining ceramic ring, so that despite small outer and inner diameter of the ceramic ring overall advantageous large contact surfaces of the ceramic ring to the electrode shell surface and to the inner wall of the housing and good heat dissipation from the electrode to the housing.

In the case of the at least one further electrode, in which preferably no magnet arrangement for beam focusing in the longitudinal axis is given more, the larger inner and / or outer diameter of the ceramic ring and corresponding thereto by the larger diameter of the electrode lateral surface are large contact surfaces of the ceramic ring to housing inner wall and to Given electrode surface. For such a further Auffängerstufe a greater length of the electrode shell surface is typically given in known purely electrostatic Auffängern than for the first stage, so that in the inventive structure for the electrode of such a further Auffängerstufe by the larger inner and / or outer diameter of the ceramic ring in Connection with the larger overall length are given large contact surfaces for heat dissipation from the electrode to the housing. In such a further catcher stage without magnetic beam guidance, the heat input by incident electrons is not concentrated on an area close to the longitudinal axis, so that the larger diameter of the electrode jacket area than the first catcher stage is not of particular disadvantage.

The inner diameter of the spacer arrangement of the at least one further catcher stage is advantageously at least 25%, in particular at least 40%, larger than the inner diameter of the first stage. Also the Outer diameter of the spacer assembly is larger in the at least one further catcher stage than in the first catcher stage, wherein the relative differences in the outer diameters may be smaller. With the assumed substantially equal thickness of the ceramic rings within the multiple stages, the inner diameter and outer diameter of the ceramic rings are correlated with each other. In particular, with possibly different radial thicknesses of the ceramic rings in the individual catcher stages, the differences in the thicknesses are small compared to the differences in the inner diameters and outer diameters.

In an advantageous embodiment, in the first catcher stage, the radial thickness of the spacer assembly and the tension of the electrode against the catcher shell may be less than in the at least one further catcher stage. Due to the smaller radial thickness, the heat dissipation from the electrode to the catcher shell is advantageously improved, and given a diameter of the electrode shell surface, the outer shell and thus also the magnet arrangement can move closer to the longitudinal axis in the region of the first catcher stage.

The invention is described below with reference to preferred embodiments with reference to the figure in FIG 1 , which shows a schematic sectional view of a catcher, still illustrated in detail.

1 shows a schematic sectional view through an embodiment of a catcher according to the invention with a longitudinal axis LA of the catcher containing cutting plane. The direction of the extension of the direction of the bundled electron beam ES emerging from the delay line VZ is considered as the longitudinal axis LA or the longitudinal direction of the collector. Preferably, the catcher is in its essential components at least approximately rotationally symmetrical about the longitudinal axis LA. There are also interceptors known with respect to the longitudinal axis and the beam extension unbalanced structure.

The bundled electron beam ES emerging from the delay line enters into a beam entry opening OE of the catcher, which is delimited by an opening in the electrode E1 of the first catcher stage A1 surrounding the longitudinal axis LA. The opening width of the opening OE is small in order to largely intercept inverting electrons in the receiver. The electrode E1 continues radially outward from the beam entry opening OE with respect to the longitudinal axis LA, wherein the electrode typically has a slightly conical course in this section. The conical profile of the electrode E1 of the first catcher stage A1 leads to an electrode jacket surface M1 of the first electrode E1, which in the preferred embodiment outlined extends essentially circularly about the longitudinal axis LA. The axial extent of the circular-cylindrical electrode jacket surface M1, which is axial with respect to the longitudinal axis LA, is denoted by L1.

The electrode jacket surface M1 of the electrode E1 of the first catcher stage AS1 bears against the inner surface of a ceramic ring R1. The radially outwardly facing surface of the ceramic ring R1 bears against the inner wall of an outer shell AH of the collector.

The outer sleeve AH is typically metallic and may in particular consist of a good heat-conducting material, in particular copper, aluminum, magnesium or alloys with such materials. The ceramic ring R1 serves for the mechanical fixing of the electrode E1 of the first catcher stage AS1 and furthermore for the electrical insulation of the electrode E1 against the outer shell AH and for the transfer of heat loss at the electrode E1 to the outer shell AH. The thermal conductivity of the ceramic materials typically used is small in comparison to the thermal conductivity of the metallic electrode E1 or the metallic outer shell AH, so that it is assumed below that the thermal resistance in the derivation of loss of heat at the electrode E1 on the outer shell AH or . A cooling device with this good thermally allied cooling device is essentially determined by the ceramic ring R1. In addition to the material properties of the ceramic material used, the radial thickness DR of the ceramic ring and the size of the contact surfaces of the ceramic ring on the outer diameter of the outer shell AH and on the inner diameter of the electrode shell area M1 are decisive for the thermal resistance of the ceramic ring R1. The inner diameter of the ceramic ring R1 is denoted by D1. The wall thickness of the electrode lateral surface M1 is small compared to the diameter D1 and the ring thickness DR and therefore neglected in the following considerations.

On the outer circumference of the wall of the outer shell AH, in the longitudinal region of the first catcher stage AS1, in particular in a longitudinal region lying in the direction of the electron beam axially to the opening OE of the electrode E1, a magnet arrangement is arranged, which is preferably designed as a ring magnet RM1 with magnetic poles opposed in the longitudinal direction , The magnet arrangement causes in the region of the longitudinal axis LA a magnetic field which acts in a bundling manner on the electron beam entering the first catcher stage AS1, in particular on the electrons which are still rapidly moving in this longitudinal section of the catcher. As a result, especially in the electron beam, the electrons whose Speed at the exit from the delay line is assigned to one of the subsequent catcher stages of the collector, held close to the longitudinal axis and a typical for purely electrostatic collectors fast beam expansion is avoided. Thereby, the axial distance between the inlet opening OE and the subsequent catcher AS2 compared to purely electrostatic Auffängern be kept large and the electrode shell surface M1 of the first electrode E1 may have a long overall length, which is slightly larger than the axial length of the designated L1 in the example outlined Ceramic ring R1. The contact surface between the inner wall of the ceramic ring R1 and the electrode jacket surface M1 is then given by the length L1 of the ceramic ring R1 and by the inner diameter D1 of the ceramic ring R1.

The diameter D1 is advantageously not more than 200%, in particular not more than 150% of the length L1 of the contact surface between the electrode jacket surface M1 and the ceramic ring R1.

In the in 1 sketched example follows in the direction of the longitudinal axis LA and in the propagation direction of the electron beam ES a second catcher stage AS2, which is also in the beam-collimating influence range of the magnet assembly RM1, in particular with respect to their inlet opening of the electrode E2 of this second catcher stage AS2. The electrode E2 continues in an analogous manner to the first catcher stage AS1 in a substantially circular cylindrical electrode surface M2, which mechanically fixed via a ceramic ring R2 relative to the outer shell AH, electrically insulated from the outer shell AH and the dissipation of heat loss to the outer shell AH with this connected is. The second Auffängerstufe is the same in terms of the dimensions of the ceramic ring R2 in the example shown as the first Auffängerstufe AS1. The magnet arrangement RM1 unfolds the beam-bundling effect, in particular in the longitudinal region, and at the inlet opening of the electrode E2 of the second catcher stage. The magnetic arrangement RM1 can be influenced in a manner known per se by magnetically focused catcher arrangements by additional magnetic elements, in particular soft magnetic elements, such that the magnetic field is not exactly rotationally symmetrical, but has a deliberate asymmetry of the type that reversing and close to the longitudinal axis, ie electrons running in the right-to-left image can be directed radially away from the longitudinal axis onto the electrode E1 or E2 and thus can not get back into the delay line.

The catcher stage AS2 is followed, in the longitudinal direction in the direction of propagation of the electron beam, by a catcher stage AS3 and by a fourth catcher stage AS4, which is cup-shaped closed in the beam direction. These scavenger stages are further scavenger stages within the meaning of the present invention. In the longitudinal areas of these Auffängerstufen no magnet arrangements are given, so that the behavior of the electron beam here corresponds to that of the pure electrostatic collector and the electron beam expands rapidly after entering the third catcher stage AS3. For the electrodes E3 and E4 of the third catcher stage AS3 and the fourth catcher stage AS4, the propagation direction of the electron beam is again provided by conical sections directed in the opposite direction and electrode shell surfaces which are substantially circular with respect to the longitudinal axis LA. The geometric design of these electrodes may differ from the sketched form. Various geometric configurations of such electrodes are known per se.

The cylindrical electrode shell surfaces M3 and M4 of the electrodes of the third and fourth catcher stage AS3, AS4 are in turn thermally conductively connected via ceramic rings R3 and R4, respectively, to the outer shell AH and form electrical insulators between the electrodes and the outer shell. For the catcher stages AS3 and AS4, the same inner diameter DW and the same outer diameter AW are assumed. In particular, the inner diameter of the ceramic rings R3, R4 can also be different from each other. The inner diameter DW of the ceramic ring R3 of the further catcher stage AS3 is advantageously at least 25%, in particular at least 40% larger than the inner diameter D1 of the ceramic ring R1 of the first catcher stage AS1. Also, the outer diameter AW of the further catcher stage AS3 is greater than the outer diameter A1 of the first catcher stage AS1. the relative diameter difference is typically less than the inner diameters D1, DW. As a result of the large diameter DW, AW compared to the first catcher stage AS1, the contact surfaces of the electrode jacket surface M3 of the third catcher stage AS3 and, correspondingly, the electrode jacket surface M4 of the catcher stage AS3 also have a large contact surface with the ceramic ring R3 or R4 and thus a large one , for the heat transfer from the electrodes to the outer shell AH authoritative material cross-section of the ceramic rings whose axial lengths are denoted by L3 for the third catcher stage AS3 and L4 for the fourth catcher stage AS4.

In the figure, the same radial thicknesses of the ceramic rings are assumed for the individual catcher stages. In an advantageous development, it can be provided that, in at least the first catcher stage AS1, the radial thickness of the ceramic ring is lower than in the third and / or fourth catcher stage and at the same time more conventional Type the voltage between the electrode and outer shell is lower at the first catcher stage than at the other catcher stages.

Instead of the ceramic rings separate for each catcher stage, common ceramic rings may also be provided for two or more adjacent catcher stages. Instead of the circumferentially closed ceramic rings and a plurality of circumferentially distributed spacers may be provided. The electrical leads to the electrodes of the individual catcher stages are not shown for clarity. Typically, such lines are led out at the inlet opening OE opposite end face of the catcher through the outer shell AH. The outer shell AH forms a vacuum-tight envelope around the multi-stage electrode assembly of the catcher. The features indicated above and in the claims, as well as the features which can be seen in the figures, can be implemented advantageously both individually and in various combinations. The invention is not limited to the exemplary embodiments described, but can be modified in many ways within the scope of expert knowledge. In particular, as known per se, the number of catcher stages may vary.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• EP 0276090 B1 [0003]
• DE 69804954 T2 [0003, 0005]
• DE 60225412 T2 [0004, 0005]
• US 4096409 [0006]
• US 6094009 [0007]
• US 5780970 [0008]

Cited non-patent literature

• "Technical Tubes" by J. Bretting, 1991, ISBN 3-7785-1645-0, on page 177 [0004]

Claims (9)

Receiver for a traveling wave tube with a plurality of successively arranged in the direction of a longitudinal axis (LA) and a Auffanger (AH) Auffängerstufen (AS1, AS2, AS3, AS4), wherein at least one of a jet entrance opening (OE) of the catcher facing first catcher stage (AS1 ) and at least one further catcher step (AS3) facing away from the beam entry opening are provided, and the electrodes (E1) of the first (AS1) and the at least one further (AS3) catcher stages each have a jacket section, which has the electrodes via electrically insulating distance arrangements (R1, R3 ) thermally conductively connected to the catcher shell (AH), characterized in that the inner diameter (D1) and outer diameter (A1) of the spacer arrangement (R1) in the first catcher stage (AS1) are smaller than the inner diameter (DW) and outer diameter (AW) of the spacer assembly (R3) in at least one other catcher stage (AS3), and that lower st in the longitudinal region of the first catcher stage (AS1) is provided axially after the inlet opening for establishing a bundling of an electron beam on the longitudinal axis magnet assembly (RM1). A catcher according to claim 1, characterized in that in the longitudinal region of the at least one further electrode no arranged for focusing of the electron beam in the longitudinal axis magnet arrangement is provided. An interceptor according to claim 1 or 2, characterized in that inner diameter (DW) and / or outer diameter (AW) of the spacer arrangement (R3) in the at least one further Auffängerstufe (AS3) by at least 30%, in particular by at least 50% greater than that Inner diameter (D1) and outer diameter (A1) of the spacer assembly (R1) at the first catcher stage (AS1). A catcher according to one of claims 1 to 3, characterized in that in the first catcher stage (A1) the inside diameter (D1) of the spacer arrangement (R1) is not more than 200%, in particular not more than 150% of the axial length of the contact surface between the electrode jacket face (A1). M1) and distance arrangement (R1). Trapper according to one of claims 1 to 4, characterized in that between the first (AS1) and the further (AS3) Auffängerstufe a second Auffängerstufe (AS2) inserted with respect to the other Auffängerstufe lesser inner and / or outer diameter of the spacer assembly (R2) is. Trapper according to one of claims 1 to 5, characterized in that in the longitudinal direction successively two further catcher stages (AS3, AS4) with respect to the first catcher stage (AS1) larger inner and / or outer diameters are provided. Trapper according to one of claims 1 to 6, characterized in that the distance arrangements (R1, R2, R3, R4) form annular bodies, in particular made of ceramic, which surface on the Auffangerhülle (AH) and on the electrode shell surfaces (M1, M2, M3 , M4). A catcher according to any one of claims 1 to 7, characterized in that in the first catcher stage (AS1) the radial thickness of the spacer assembly (R1) and the tension of the electrode (E1, M1) against the catcher shell (AH) are less than the thickness of the Distance arrangement (R3) and the voltage of the electrode (E3, M3) in the at least one further Auffängerstufe. A traveling field tube with an electron beam source, a delay line and with a catcher according to one of claims 1 to 8.

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