JPS5846515Y2 - traveling wave tube with metal envelope - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a traveling wave tube having a metal envelope, in particular a traveling wave tube that is housed in a metal case and operates at a potential of the collector at a lower potential than the DC potential of the slow wave circuit. This invention relates to an improvement in a traveling wave tube having a lowered collector.

It is well known that the overall efficiency of traveling wave tubes can be improved by operating the collector with a potential lower than the DC potential of the slow wave circuit. This is a common practice as it also reduces the number of people.

In this case, the collector needs to be electrically isolated from the slow wave circuit.

Furthermore, in the case of a traveling wave tube with a metal vacuum envelope, the metal vacuum envelope has the same potential as the DC potential of the slow wave circuit.
If the case is made of metal, the case also becomes the DC potential of the slow wave circuit, so it is necessary to electrically insulate the collector, the metal vacuum envelope, and the case.

Figure 1a shows a conventional traveling wave tube with a metal vacuum envelope, in which a spiral is used as the slow wave circuit and a periodic magnetic field device is used as the electron beam focusing magnetic field, and the traveling wave tube is housed in a metal case. FIG. 1 is a sectional view taken along line A-A in FIG. 1a.

In FIGS. 1a and 1), an electron beam is generated by an electron gun 1, which is focused by a periodic magnetic field device 5 and guided to a collector 6 via a slow wave circuit 2.

7 is a ceramic ring that electrically insulates the collector 6 and the metal vacuum envelope 8.

The microwave to be amplified is passed from the input line 3 to the slow wave circuit 2.
The electron beam is guided to the electron beam, is amplified by interaction with the electron beam, and is taken out from the output line 4.

The heat generated in the collector 6 is conducted to the metal case substrate 13 via a heat radiator 9 that surrounds the circumferential side surface of the collector 6, and is radiated to the outside.

A DC potential is applied to the collector 6 through a lead wire 10 connected to a heat sink 9 .

A case substrate 13 and a case cover 14 constitute a case 15, which are usually made of non-magnetic metal in consideration of heat dissipation and influence on the magnetic field created by the periodic magnetic field device 5.

In the case of a traveling wave tube having a metal vacuum envelope, the case 15 has the same potential as the DC potential of the slow wave circuit 2, and at the same time serves as a grounding point.

Therefore, in order to operate the collector 6 at a lower potential than the DC potential of the slow wave circuit 2, the collector 6 and the case 15 need to be electrically insulated.

A flat insulator 11 performs this function, and insulates between the metal heat sink 9 and the heat sink 12.

As the insulator 11, an insulating material with good thermal conductivity such as beryllia porcelain or alumina porcelain is usually selected.

The above is the basic operating structure of a traveling wave tube, but in addition,
In order to fix the periodic magnetic field device 5 and for safety against high voltage, it is recommended to fill the space between the traveling wave tube body and the case 15 with a filler 16 having good electrical insulation properties such as epoxy resin or silicone rubber. Common.

Particularly, in the case of a traveling wave tube that must be operated in a vacuum state, such as one used on a satellite, it is absolutely necessary to fill the tube with the filler 16 in order to prevent discharge in a unique vacuum.

In other words, as the pressure gradually decreases from atmospheric pressure,
Since a unique vacuum exists, which is a pressure state in which discharge is very likely to occur, a discharge phenomenon will occur in the collector portion where there is a large potential difference with the case 15 without the filler 16.

The filler 16 is poured in liquid form and then hardened by natural hardening or thermal hardening.

However, since the filler 16 is filled so as to surround the collector 6 and the metal heat sink 9 to which high voltage is applied via the lead wire 10, cracks or cracks may occur in the filler 16 between the heat sink 9 and the case cover 14. If this occurs, the insulation between the collector 6 and the case cover 14 may deteriorate, making it impossible for the traveling wave tube to operate.

Especially when using epoxy resin as the filler 16,
The hardness of the epoxy resin increases during low-temperature operation of the traveling wave tube, and under severe environmental conditions such as thermal shock and thermal cycles, or in environmental conditions with a wide temperature range (e.g. -40 to +70°C), the filler 16 may crack or Cracks are likely to occur, and if cracks or fissures that are large enough to reach the case cover 14 from the collector 6 or the metal heat radiator 9 occur, the withstand voltage will be poor in the vacuum of the singular space.

In other words, in the conventional structure, the operating temperature range of the traveling wave tube is limited by the temperature characteristics of the filler, and there is a drawback that the operating temperature range cannot be widened.

The present invention improves the drawbacks of the conventional structure mentioned above,
The object of the present invention is to provide a traveling wave tube that does not suffer from breakdown voltage defects even in a unique vacuum and operates stably over a wide temperature range.

Figure 2a shows the part related to the present invention when the present invention is applied to a traveling wave tube using a spiral as a slow wave circuit. It is a diagram.

In FIG. 2 a, l), the end 1 of the metallic vacuum envelope 8
An insulating porcelain cylinder 18 whose both end faces are metallized is fixed to 7 by brazing or the like, and a collector 19 is disposed inside the insulating porcelain cylinder 18. A metal plate 20 serving as the bottom of the housing 19 and an insulating porcelain plate 21 whose one side is metallized are fixed by brazing and vacuum sealed.

The collector 19 is provided with a groove 22 extending in the longitudinal direction, and the outer diameter of the collector 19 that fits into the insulating porcelain tube 18 is selected to be slightly larger than the inner diameter of the insulating porcelain tube 18.

Insertion of the collector 19 into the inside of the insulating porcelain cylinder 18 is achieved by narrowing the width of the slot 22 provided in advance in the collector 19 by mechanical force from the outside, thereby effectively reducing the outer diameter of the collector 19 into the insulating porcelain tube. This is done by making the inner diameter of the collector 19 smaller than the inner diameter of the cylinder 18, and when the mechanical force from the outside is removed from the collector 19 at a predetermined position inside the insulating porcelain cylinder 18, the split groove 22 expands due to the elasticity of the collector 19 and is stably held. Fixed.

Heat generated in the collector 19 is radiated to the substrate 13 via the insulating porcelain tube 18 and the heat sink 12.

A lead wire 10 for applying a high voltage is attached to a part of the outer surface of the metal plate 20 by soldering or the like, and a filler 16 is filled into a gap formed in the case cover 14.

Electrical insulation between the collector 19 and the metallic envelope 8 and the case substrate 13 serving as a grounding point is maintained by the insulating porcelain cylinder 18 .

As the porcelain material for the insulating porcelain cylinder 18, it is preferable to use a porcelain material that has good thermal conductivity and high electrical insulation resistance, such as conventionally used beryllia porcelain or alumina porcelain.

The thickness of the insulating porcelain tube 18 is determined by considering the elasticity of the collector 19, the voltage applied to the collector 1, the power consumed by the collector 19, etc., and a thickness of 1 to 2 mm is sufficient.

As the material of the collector 19, copper, which has good thermal conductivity, or molybutton, which has lower thermal conductivity than copper but does not melt, is used.

It is possible to improve the thermal resistance between the heat sink 12 and the insulating porcelain tube 18 by interposing an adhesive with good conductivity in the contact between the heat sink 12 and the insulating porcelain tube 18.

In the present invention, since the collector 19 is surrounded by an insulating porcelain cylinder 18 and held and fixed in a vacuum, the collector 19
There is no part exposed to the case cover 14 and case substrate 13 that serve as grounding points, and the exposed area is only the outer surface of the metal plate 20, which is greatly reduced. Even if cracks or cracks occur in the filler 16 between the tube 18 and the case cover 14, they do not reach the collector 19, so even if the traveling wave tube is operated in a specific vacuum, no pressure resistance failure will occur.

Most of the insulation between the collector 19 and the ground point is done by the insulating porcelain cylinder 18, and the filler 16 only plays an auxiliary role, so cracks or cracks in the filler 16 have no effect on the performance of the traveling wave tube, and the filling The operating temperature range is significantly expanded without being limited by the temperature characteristics of the material 16.

Furthermore, in the present invention, the collector 19 is held and fixed in vacuum by the elasticity of the collector 19 having the grooves 22, so even if the collector 19 is heated to several hundred degrees by an electron beam, the collector 19 will not be oxidized, and the collector 19 will not be oxidized. Since the expansion caused by the temperature rise of 19 is absorbed in the direction in which the width of the groove 22 becomes narrower, the allowable power of the collector, which does not apply abnormal force to the insulating porcelain cylinder 18, is improved.

In this embodiment, a metal plate 20 and an insulating porcelain plate 21 are fixed to the bottom of the collector 19 by brazing and vacuum-sealed, but only one of them, for example, the metal plate 20 constitutes the bottom of the collector 19. You can also do that.

In such a structure, the case cover 1 serves as the grounding point.
4. The area exposed to the case board 13 is as shown in Fig. 2a,
The lead wire for applying high voltage is 10, although it is slightly larger than 1).
can be easily attached to a part of the metal plate 20 that forms the bottom of the collector 19 by soldering or the like.

As described above, the present invention has a collector that is placed inside an insulating porcelain cylinder that serves as a vacuum envelope, and is fixed in close contact with the insulating porcelain cylinder in a vacuum, thereby achieving a higher withstand voltage than the conventional one. It is possible to obtain an excellent traveling wave tube with improved collector power tolerance.

The effect is particularly noticeable when used in a singular vacuum, such as in a traveling wave tube mounted on a satellite.

[Brief explanation of drawings]

Figures 1a and 1) are axial and A-A cross-sectional views of a conventional traveling wave tube with a metal envelope, and Figures 2 a and b are axial cross-sectional views showing an embodiment of the present invention, respectively. and BB sectional view. In the figure, 1...electron gun, 2...
・Slow wave circuit, 3... Input line, 4... Output line, 5... Periodic magnetic field device, 6... Collector, 7... ...Ceramic ring, 8...
Metal vacuum outer container, 9... Heat sink, 10...
... Lead wire, 11 ... Insulator, 12 ...
... Heat sink, 13... Case board, 14...
...Case cover, 15...Case board 13
A case composed of a case cover 14 and a case cover 14;
...Filling material, 17...End of metallic vacuum envelope 8, 18.19...Insulating porcelain cylinder and dividing groove 22 according to the present invention in the longitudinal direction 20 is a metal plate serving as the bottom of the collector 19, 21...
...Indicates an insulating porcelain plate.

Claims (1)

[Scope of utility model registration request] an electron gun that generates an electron beam; a slow-wave circuit that amplifies the microwave through interaction between the electron beam and the microwave; and an electron beam that has finished participating in the amplification of the microwave in the slow-wave circuit. a collector to which a potential lower than the potential of the slow wave circuit for collecting the slow wave circuit is applied;
In the traveling wave tube having the electron gun and a metal vacuum envelope containing a slow wave circuit, one end of an insulating porcelain tube that becomes a part of the vacuum envelope is provided at an end of the metal vacuum envelope. is fixed, a collector having an outer diameter larger than the inner diameter of the insulating porcelain cylinder and having grooves in the direction of the cylinder is mounted inside the insulating porcelain cylinder, and the other end of the insulating porcelain cylinder is attached to a metal plate. A traveling wave tube having a metal envelope, characterized in that the envelope is vacuum-sealed by an insulating porcelain plate and/or an insulating porcelain plate.