JPS5853135A - Traveling-wave tube - Google Patents

Abstract

PURPOSE:To facilitate the impression of an axial asymmetric magnetic field to a collector and to restrain the flow of backward electrons to a delayed wave circuit and thereby to obtain a traveling-wave tube with high efficiency and high reliability, by a method wherein magnetic pole pieces made of iron or nickel or the like are hermetically sealed and fixed by fusing or the like to the two slit places of the collector so that said magnetic pole pieces project from the inside and outside of the circumference of the collector. CONSTITUTION:A collector 5 is made of non-magnetic material (for instance: copper), at a part on the external surface of the collector 5 the slits are grooved at two places in parallel with the direction of an electron beam axis, and magnetic iron pieces 15 and 16 made of iron or nickel are fixed to and sealed in the slit parts. The magnetic field intensity 19 is proportional to the thickness and the length of a permanent magnet 18 and the lengtn of the projected part of magnetic pole pieces 15 and 16 in the collector 5, therefore said intensity is variable for a wide range by adjusting those dimensions. The ratio (d2/d1) of the inside diameter d2 of the collector to the inside diameter d1 of the collector inlet can be enlarged enough, so the collector structure can be made to be an ideal Faraday cage style.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a traveling wave tube having a potential 1-type collector that operates with the collector potential lower than the DC potential of the slow wave circuit.

It is well known that in traveling wave '#, the overall efficiency can be improved by operating the collector with the potential lower than the DC potential of the slow wave circuit. This is a common practice as it also reduces calorific value. In this case, the collector needs to be electrically isolated from the slow wave circuit. Furthermore, in the case of a traveling wave tube that has a metallic vacuum envelope, the metallic vacuum envelope has the same potential as the DC potential of the slow wave circuit, and if the case that houses the traveling wave tube's bulb is metallic, , the case is also a slow wave circuit I! Since the potential is fi, it is necessary to electrically insulate between the 1 collector and the case.

The first LIA (a) is a conventional traveling wave tube i! Figure 1 (b) shows a traveling wave tube that uses a spiral as a wave circuit and has a periodic magnetic field device as an electron beam flux magnetic field and is housed in a metal case. Figure n 8g1 (匈, (-) showing a cross-sectional view of -A, an electron beam 2 is generated by an electron gun l, this electron beam 2 is focused by a periodic magnetic field device 3, and a slow wave circuit 4td: f
f 06 guided to the collector 5 is a ceramic ring that electrically insulates the collector 5 and the metal vacuum envelope 7 0 The microwave to be amplified is fed from the input +13I8 to the slow wave circuit 4
It is amplified by interaction with the electron beam and taken out from the output line 9. A DC potential is applied to the collector 5 through a lead (not shown) K connected to a heat sink loK.

In the case of a traveling wave tube having a metal vacuum envelope 7, the case 11 is at the same potential as the DC potential of the slow wave circuit 4, and also serves as a ground point. For rounding to operate at a potential lower than 1, it is necessary to electrically insulate the collector 5 and case 11. The plate-like insulator 12 provides insulation between the metal heat sink 10 and the heat sink 130. For the insulator 11, an insulating material with good thermal conductivity such as beryllia porcelain or alumina porcelain is usually selected, and for the collector 5, a non-magnetic steel with high thermal conductivity is used. The structure of the collector 5 that captures the beam is generally of the 77 Radicage type (the inner diameter d2 of the collector is larger than the inner diameter d1 of the collector so that there is no electric field inside the collector). When the electron beam 2 is captured by the collector 5, the secondary electrons 21 are emitted from the collector 5 because they collide with the collector 5 due to a speed change. The electrons become accelerated and rush into the slow wave circuit, which is insulated from the collector 5 and to which a higher potential than the collector 5 is applied, as so-called return electrons. The rice feeding slow wave circuit 1IIE current increases, and furthermore, the slow wave circuit's magnetization of true 9 degrees due to heat and the ion noise Jll/
III etc., which results in deterioration of the traveling wave tube's performance characteristics and reliability. If the potential amounts of the collector voltage and the slow wave circuit voltage are large, the number of return electrons will increase, so the collector potential decrease -1, that is, the efficiency of the traveling wave tube will be limited.

In order to prevent the above-mentioned backward movement of secondary electrons, it has been suggested that an axially asymmetrical magnetic field should be applied to the electron beam 2 near the collector 5. An electron deflection magnet 14 was disposed on a part of the surface. However, in such a structure, the collector 5 is made into a 772-decage type and the collector inner diameter d! If you try to increase the ratio of the to the inner diameter of the collector inlet, the resulting KF
It is necessary to increase the inner diameter d of the collector, resulting in a large collector, and the electron deflection magnet 14 is distanced from the center of the collector 5, making it difficult to apply an axially asymmetrical magnetic field to the collector 5.

In addition, in a high-power traveling wave tube, the amount of heat generated by the collector 50 increases, and the surface area of the collector 5 needs to be increased according to the power consumed by the collector 5. When an axially asymmetric magnetic field is applied to the f slow wave circuit 4, the number of electrons returned to the f slow wave circuit 4 becomes large, and the combined efficiency cannot be significantly improved.

The present invention eliminates these drawbacks, facilitates the application of an axially asymmetrical magnetic field to the collector, suppresses the R stain to the slow wave (C) path, and provides high-power traveling wave tubes and ion beams with high efficiency. The purpose of the present invention is to provide a traveling wave tube that generates only one signal with little noise.

The present invention provides a traveling wave tube having a collector to which a potential lower than the potential of a -wave circuit is applied, a metal vacuum envelope containing an electron gun, and a slow wave circuit. A magnetic pole piece made of iron or nickel is attached to the slotted part by brazing or the like so that it protrudes from the inner and outer periphery of the collector, and a semi-cylindrical piece is attached to the outer half of the collector A ceramic part is disposed on the opposite outer circumferential half, and a semi-cylindrical permanent magnet magnetized in the circumferential direction is disposed in close contact with a magnetic pole piece protruding from the outer circumference of the collector. shall be.

Next, the present invention will be explained to #P#411 with reference to the drawings.

FIG. 2 (13, (bJ) is an embodiment of the present invention. In the figure, the collector 5 is made of non-magnetic material (for example, steel).

Two parallel slots are made in a part of the outer surface of the collector 5 in the direction of the electron beam cap, and magnetic pole pieces 15 and 16 made of iron or nickel are fixed and sealed in the slots by soldering. A semi-cylindrical ceramic component 17 is disposed on one half of the outer circumference of the O collector 5.
16 and the ceramic component 17, and the heat generated in the collector 6 is electrically insulated by the ceramic component 17.
The heat is transmitted to the case 1G using the heat dissipation stand 12 as a heat transfer path, and is further radiated by heat dissipation vanes (not shown) attached to the case. A semi-cylindrical permanent magnet 18 is disposed on the opposing upper half of the outer part of the collector 5 so as to be closely layered with the magnetic pole pieces 15 and 16, and a magnetic field is formed in the center of the collector 5. The permanent magnet 18 is circularly rounded, and the magnetic pole pieces 15 and 16 are S and N poles, respectively.
The lines of magnetic force (magnetic field) as shown in FIG. Licum cobalt magnets or alnico magnets with good thermal resistance properties are suitable. The magnetic field strength 19 is proportional to the thickness and length of the permanent magnet 18 and the length of the protrusion of the magnetic pole pieces 15 and 16 within the collector 5, and can be varied over a wide range by adjusting these dimensions. In such a structure, the ratio (dt/dl) between the collector inlet inner diameter d1 and the collector inner diameter d can be made sufficiently large, and the collector structure can be formed into an ideal Faraday cage shape. With the addition of the effect of the magnetic field applied to the collector section, it is possible to obtain a highly reliable traveling tube with less electrons returning from the collector section and less ion noise. Also, even if the collector is made larger by increasing the outer diameter of the collector part, by making the magnetic pole pieces protrude inside the collector,
It is possible to easily obtain the required magnetic field to the collector, suppress the return electrons when the electron beam collides inside the collector, and furthermore, the increase in the collector surface area makes it easier to dissipate heat from the collector. Increasing the allowable power is the Loe ability, and it is possible to obtain a progressing ureter with high power. In Figures 2 (a) and (b), U,
4a Pole piece 15.16 (2) Although the shape is plate-like, it does not necessarily have to be plate-shaped, and when it is necessary to obtain a sharp magnetic field distribution inside the collector, the magnetic pole piece 15.16 is shown in Figure 3. It can be made into a T-shape like this.

[Brief explanation of the drawing]

Figure 1 (al, (bl) is a sectional view and A-A sectional view of a traveling wave tube with a conventional metal envelope, respectively, and Figure 2 (b) is an embodiment of the present invention, respectively. An axial cross-sectional view and a H-H cross-sectional view of main parts showing an example, and FIG.
), (b) is a perspective view of another embodiment of the pole piece 15,16;

Claims (1)

[Claims] In a traveling wave tube having a collector to which a potential lower than that of the slow wave circuit is applied, an electron gun, and a metal vacuum envelope containing the slow wave circuit, there are two locations on the outer periphery of the cylinder in the longitudinal axis direction. A magnetic pole piece made of iron or nickel is fixed and sealed by brazing or the like so that it protrudes from the inner and outer periphery of the collector, and a cylindrical ceramic plate is attached to the outer half of the collector. A semi-cylindrical permanent magnet magnetized in the circumferential direction is arranged in close contact with a magnetic pole piece protruding from the outer periphery of the collector on the other outer periphery half of the collector. Wave tube.