JP3075753B2 - Electron beam tube with input cavity - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to electron beam tube arrays, and more particularly to an input resonant cavity for applying high frequency energy to the array.

[0002]

BACKGROUND OF THE INVENTION The present invention relates to Christ Road (Varian,
It is particularly applicable to inductive output tetrode devices (IOT), such as Associates®. Inductive output tetrodes (hereinafter abbreviated as IOT) are well known, but previously proposed designs have been developed to cover the entire frequency range of television (e.g.
In order to obtain the required instantaneous bandwidth (e.g., 8 MHz) over 70-860 MHz), it is necessary to use a plurality of tubes, and each tube must be used with a plurality of different cavities. there were. At present, in the case of klystrons, the various cavities arranged along the electron beam path are tuned (staggered) and the outputs of different frequencies are combined to achieve this requirement by obtaining the required bandwidth. I have. However, this is not possible with ordinary IOT designs.

Other problems resulting from high voltages, on the order of 30 kV, which must be applied to the cathode and grid, should be noted in normal use, especially since the input cavity can be the outer part of the IOT.

[0004]

SUMMARY OF THE INVENTION The present invention provides an apparatus that eliminates or alleviates some or all of the problems associated with maintaining high cathode and grid voltages while keeping the IOT suitable for television applications. An electron beam tube arrangement according to the present invention comprises a resonant cavity at least partially defined by an inner body portion and an outer body portion, wherein the inner body portion is maintained at a high voltage with respect to the outer body portion, Have no conductive connection between them.

[0005] "High voltage" means a voltage of about several tens of kV. Although the invention will be described with respect to an IOT device, it will be apparent that it can be applied to other forms of electron beam tube arrays having an input resonant cavity such as a klystron. Typically, the outer body part is at a very low voltage and is usually grounded. The two body parts are preferably physically connected to each other by means of a dielectric insulator part which is advantageously molded. The two body parts may also be provided with interengaging means to assist in joining the two body parts.
These measures allow the required voltage difference between the outer body part and the inner body part to be maintained by limiting the path to a very high impedance for direct current, while at the coupling point for high frequencies. Advantageously, the dimensions are such that they exhibit a very low impedance and prevent high frequencies from leaking out of the cavity.

[0006] It may be preferred to provide the electrical connection through an insulator material between the outside of the cavity and the inner body part. Advantageously, the input resonant cavity is a primary cavity and comprises a secondary resonant cavity coupled to the primary cavity.
Preferably, each of these cavities is tuned to a different frequency so that it can be used with a larger bandwidth than if only one cavity was used.

[0007] The resonance frequencies of the primary and secondary cavities are tunable. Tuning may be performed independently or, for example, linked such that changing the resonance frequency of one cavity changes the resonance frequency of the other cavity accordingly. The volume of the primary cavity can be varied by means included in the outer body part to adjust the resonance frequency.

An embodiment of the present invention will be described below with reference to the accompanying drawings.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The IOT shown in FIG.
And an output section 16 in combination with the drift tubes 18,20. The input assembly, including the electron gun 10, the cathode 12, and the grid 14, comprises a primary input cavity 2
It is surrounded by two. Primary input cavity 22 is coupled to secondary input cavity 24 having output coupler 26. The output section 16 is surrounded by a primary output cavity 28, which is coupled to a secondary output cavity 30 having an output coupler 32.

During use, a high frequency voltage of several hundred volts is generated between the cathode 12 and the grid 14, and both are maintained at about 30 kV. The grid 14 also needs to maintain a negative DC bias voltage of about several hundred volts with respect to the cathode 12. More particularly, the invention relates to the primary input cavity 22 of the illustrated device.
The inner body portion 40 includes an upper annular metal plate 70 and a lower annular metal plate 71, which are separated by a dielectric material 73 to define an annular channel. Upper plate 7
0 is electrically connected to the cathode 12 and the lower plate 71 is
4 is electrically connected. The open portion of this channel is outwardly facing and surrounds the open portion of another annular channel including a metal outer body portion 42 (the input cavity 22 is defined by portions 40 and 42).

Angled flanges 44, 46 are provided on both sides of the outer body portion 42 to provide additional annular channels 48,
50 are limited. The free edges of the inner body part 40 project into these channels. However, there is no direct electrical contact between any portion of the inner body portion 40, any portion of the outer body portion 42, and the flanges 44, 46, and there is no insulating dielectric between them. Material 52 is molded. This serves to insulate the outer body part 42 from the inner body part 40 and therefore from the very high voltages applied during use. The use of dielectric 52 electrically isolates body portions 40, 42 while creating a potential passage for high frequency leakage through dielectric 52. Accordingly, the dimensions of the overlapping passages of the portions 40, 42 are chosen to present a very low impedance to high frequencies, so as to prevent as much high frequency leakage as possible.

The capacity of the cavity 22, and thus the resonance frequency, can be varied by conventional techniques by using a tuning door, for example, as shown at 94. A modification of the primary input cavity 22 is shown in FIG. In this example, the outer body portion 42 extends axially to form an elongated annular region 90 (this region is defined by the elongated cylindrical wall 91.92 of the body portion). The effective volume of the region 90 can be varied by a slide 93 which can be moved axially by suitable means.

In the drawings, the dielectric is shown as being smooth, but, for example, the edges are notched or provided with grooves.
By shaping the surface, the withstand voltage capability can be further improved. Power leads 54 are routed through dielectric 52 to maintain electrical insulation of outer body portion 42 while maintaining grid 14 at an appropriate bias voltage. The connection is made between the lead 54 and the plate 71.

Inside the primary input cavity 22 is a coupling loop 6.
0 and 62 are linked to the secondary input cavity 24. The internal volume of the secondary input cavity 24, and thus its resonance frequency, is adjustable by a movable plunger 64 projecting from the hole member 66. In this embodiment of the invention, the volumes of the primary cavity 22 and the secondary cavity 24 are independently variable, but they may be linked so as to move them together. The primary cavity 22 and the secondary cavity 24 have different resonance frequencies.

At the output end of the IOT, a primary output cavity 2
8 surrounds the output section 16, the cavities being tunable by conventional techniques. Cavity 28 is coupled to secondary output cavity 30 by coupling loop 80. The connection to the secondary cavity 30 includes a dome structure 82 provided on its inner wall. Tuning of the secondary cavity 30 can be performed by conventional techniques. FIG. 3 shows another embodiment of the present invention, in which only one input cavity is included in this arrangement. The input cavity of this particular arrangement is similar to that shown in FIG.

[Brief description of the drawings]

FIG. 1 is a side sectional view of an IOT according to the present invention, with some parts omitted for clarity;

FIG. 2 shows a variation of the primary input cavity,

FIG. 3 shows another embodiment according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Electron gun 12 Cathode 14 Grating 16 Output section 18 and 20 Drift tube 22 Primary input cavity 24 Secondary input cavity 26 Output coupler 28 Primary output cavity 30 Secondary output cavity 32 Output coupler 40 Inner body part 42 Outer body part 44 , 46 angled flange 48, 50 annular channel 52 insulating dielectric material 54 power lead 60, 62 coupling loop 64 plunger 66 hole member 70 upper annular metal plate 71 lower annular metal plate 73 dielectric material 80 coupling loop 82 dome structure 90 annular area 91, 92 wall of body part 42 93 sliding plate 94 tuning door

────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Mark Bridges UK Essex CM2 8 W Chelmsford Garry Wood Sharpington Close 19 (72) Inventor Edward Stanislau Soviera's Quay Chelmsford Great Bad Dosit Avenue 38 (72) Inventor Stephen Badel UK Essex CM 61 NNF Barnston High Easter Road Bishops Green 3 (58) Fields investigated (Int. Cl. ⁷ , DB name) H01J 23/20

Claims (7)

(57) [Claims] 1. An electron gun, an annular input resonance cavity surrounding the electron gun, means for applying a high-frequency signal to the input resonance cavity, and an output resonance cavity, wherein the input resonance cavity has an internal body portion. And an outer body portion, the inner body portion being maintained at a higher voltage with respect to the outer body portion, and the inner body portion being electrically connected to the electron gun. In contact, there is no conductive connection between the inner body part and the outer body part, and the input resonant cavity has two transverse walls orthogonal to the linear electron beam from the electron gun. At least one transverse wall comprising a portion of said inner body portion and a portion of said outer body portion, wherein a dielectric insulating material is interposed between said portions. Tube structure. 2. The linear electron beam tube structure according to claim 1, wherein the outer body portion is kept at a low voltage or is grounded. 3. The linear electron beam tube structure according to claim 1, wherein the inner body portion and the outer body portion are integrated by a dielectric insulating material. 4. The linear electron beam tube structure according to claim 3, wherein the outside of the input resonance cavity and the inner body portion are electrically connected via the dielectric insulating material. 5. The electron gun includes a cathode and a grid electrode, and the inner body portion has a first region electrically connected to the cathode and a second region electrically connected to the grid electrode. The linear electron beam tube structure according to any one of claims 1 to 4, comprising: 6. The input resonance cavity according to claim 1, wherein the input resonance cavity has a donut shape having a circular cross section coupled to a cylindrical body having a circular cross section. Linear electron beam tube structure. 7. An input resonance cavity in which a dielectric insulating material is sandwiched between an inner body portion and an outer body portion to generate a low impedance with respect to radio frequency at a junction between the inner body portion and the outer body portion. The linear electron beam tube structure according to any one of claims 1 to 6, wherein leakage of radio frequency from the device is prevented.