Travelling-wave tube with collector housing having all electrical connections through one end wall of housing

A travelling-wave tube comprises a delay line section, an electron collector comprising several electrodes in a cooling chamber, one end wall of which is connected to the delay line section, the several electrodes being individually mounted on an inner wall of the cooling chamber by insulation with good heat conduction characteristics and individually electrically connected to insulated bushings in the said end wall.

BACKGROUND OF THE INVENTION 
The present invention relates to a travelling-wave tube with a delay line 
section and an electron collector, comprising several electrodes, which is 
arranged inside a hollow cylindrical metal cooling chamber having one end 
surface or wall which is connected in vacuum-tight manner to the end of 
the delay line section and which has a diameter which is larger than the 
diameter of the delay line section. 
Multi-stage collectors, i.e. electron collectors having several collector 
electrodes lying one behind the other in the direction of electron beam in 
order to achieve an improved degree of efficiency, are already known in 
travelling-wave tubes. 
SUMMARY OF THE INVENTION 
It is an object of the invention to provide a new type of travelling-wave 
tube the collector of which permits an improved heat dissipation. 
A further object of the invention is to so form the collector of a 
travelling-wave tube that sufficient cooling, particularly when installing 
such a travelling-wave tube in a satellite, is ensured. 
According to a first aspect of the invention, there is provided a 
travelling-wave tube comprising a delay line section, an electron 
collector, several electrodes forming said electron collector, a cooling 
chamber in which said several electrodes are located, an end wall for said 
cooling chamber connected to said delay line section, a plurality of 
electrical insulators with good heat conduction characteristics mounted on 
an inner wall of said cooling chamber for mounting individual ones of said 
several electrodes, insulated bushings in said end wall of said cooling 
chamber, and means electrically connecting said insulated bushings to 
individual ones of said several electrodes. 
According to a second aspect of the invention, there is provided a 
travelling-wave tube having a delay line section and an electron collector 
comprising several electrodes arranged inside a hollow cylindrical metal 
cooling chamber, one end wall of which is annular, is connected to the end 
of said delay line section so as to be vacuum-tight and has a diameter 
which is greater than the diameter of said delay line section, 
characterized in that a plurality of electrical insulators which are good 
conductors of heat are fastened to the inner surface of the wall of said 
cooling chamber, said individual collector electrodes are mounted on the 
insulators so as to be good conductors of heat to, while being 
electrically insulated from, said cooling chamber, insulated bushings are 
provided on a portion of the annular surface of said end wall, which delay 
line section said extends laterally beyond said delay line section, and 
the bushings are connected to said individual collector electrodes in an 
electrically conductive manner.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
In a preferred embodiment of the invention, it is proposed, in a 
travelling-wave tube as described at the outset, to fasten a plurality of 
insulators having good thermal conductivity to the inner surface of the 
wall of the cooling chamber with the individual collector electrodes being 
mounted on the insulators so as to be good conductors of heat to, while 
being electrically insulated from, the cooling chamber and to provide 
insulated bushings on the annular surface of the end wall connected to the 
delay line section, said annular surface overlapping the delay line 
section. These bushings are electrically connected to the individual 
collector electrodes. 
The invention is described in greater detail below by means of an example 
of embodiment shown in the FIGURE. 
Referring now to the drawing, there is shown, in cross-section, a part of 
the electron collector of a satellite travelling-wave tube which is 
attached to a delay line section 2. Only part of the delay line attached 
to the electron collector is shown. This delay line is continued and on 
the other part of this line there is located, in known manner, a system 
for producing an electron beam. With the aid of magnetic focusing means, 
the electron beam in the delay line is focused in known manner on its path 
to the electron beam producing system. The electron collector, the 
remaining part of the delay line and the focusing means are not shown in 
the FIGURE for the sake of simplicity. The construction of the tube is 
preferably rotationally symmetrical about the longitudinal axis of the 
electron beam. 
The electron beam, not shown, and escaping from the delay line section 2 as 
a beam enters the collector electrode and is absorbed there, wherein the 
energy of the electron is passed on in the form of heat to the individual 
electrodes 5, 6 and 7 of the electron collector catcher. Four annular 
electrodes 5, and a cup-shaped electrode 7 into which an expanding mandrel 
6 projects with its tip counter to the electron beam are provided. The 
expanding mandrel 6 may be at the same potential as the electrode 7 or it 
may be insulated from the electrode 7 and have a separate potential which 
causes a further spreading of the remaining electron beam which has not 
been absorbed by the electrodes 5. The electrodes 5 and 7 are preferably 
at varying potentials and are separately mounted within the electron 
collector chamber 1, which forms the cooling chamber at the same time. 
The cooling chamber 1 is preferably cup-shaped and is connected 
vacuum-tight to the delay line section 2 via an end wall 3. The end wall 3 
is constructed approximately in plate form, and is provided with a number 
annular steps. In the preferred embodiment, this end wall 3 serves on the 
one hand as a mounting for the entire travelling-wave tube and on the 
other hand as a socket in which the insulated bushings 4 are arranged 
distributed over the circumference. The diameter of this end wall 3 is 
substantially larger than the diameter of the delay line section 2. The 
end wall 3 preferably comprises a turned metallic member of increased 
stability. 
The mounting of the individual collector electrodes 5, 6 and 7 takes place 
by means of the interposition of insulators 8, which are preferably 
disc-shaped. Aluminium oxide ceramics have proved to be a suitable 
material for these insulators. In order to increase the heat conductivity, 
it may occasionally be advisable to produce these insulators from 
beryllium oxide. The mounting of the electrodes 5, 6 and 7 takes place 
preferably on the inner wall of the cooling chamber 1 while interposing 
the insulating ceramics discs 8. In order to achieve good heat transfer, 
it is advisable to ensure large-area soldering to the insulators 8. 
It has proved to be advisable to provide good heat-conductive intermediate 
elements 9 at least between the electrodes and the insulators 8, which 
intermediate elements 9 preferably comprise copper and are constructed so 
that they may be deformed under varying expansion conditions of the 
electrodes and of the cooling chamber 1. These intermediate members 9 
consist, for example of copper bands which are bent like brackets. 
Furthermore, it may be advisable occasionally to additionally provide such 
intermediate members which absorb mechanical heat stresses by means of 
deformation between the insulators 8 and the cooling chamber 1. In the 
FIGURE, these parts are designated 10. The described mounting of the 
collector electrodes 5, 6 and 7 ensures on the one hand a mechanically 
stable mounting of the electrodes and on the other hand ensures that there 
is good dissipation of heat in a radial direction from the individual 
electrodes through the cooling chamber 1. For example, eight to twelve of 
these insulators 8 may be provided per electrode, with these insulators 
being distributed at a uniform spacing around the circumference of the 
electrodes. Similarly, the fastening of the expanding mandrel 6 to the 
floor wall of the cooling chamber 1 may take place via several of these 
insulators 8. 
The individual collector electrodes 5, 6 and 7 are preferably at varying 
electrical voltages, as already shown. The supply of voltages takes place 
via several insulated bushings 4 which are arranged on the end wall 3 and 
which in the interior of the chamber 1, are electrically conductively 
connected to the appropriate electrodes via wires. If the illustrated four 
plate-shaped collector electrodes 5 as well as the cup-shaped electrode 7 
and the expanding mandrel 6 are to be connected to varying potentials, 
then in the illustrated embodiment, six electrical bushings 4 distributed 
over the circumference are provided on the end wall 3. 
It is particularly useful to provide the end wall 3 with a fixing or 
mounting flange 13 on its circumference which makes possible stable 
mounting of the entire travelling-wave tube on a support structure. As 
shown in the FIGURE, the travelling-wave tube is inserted into an opening 
in a wall member 11 of the support structure so that the fastening of the 
tube is undertaken by means of the flange 13. For this purpose a plurality 
of screw connections 12 may be provided, for example, distributed over the 
circumference. By means of appropriate intermediate layers between the 
flange 13 and the wall member 11 it is possible to produce a 
pressure-tight connection. Such a pressure-tight connection is preferably 
of advantage if the travelling-wave tube is built into a satellite. Thus 
the wall 11 preferably constitutes the envelope wall of the satellite. In 
this manner the cooling chamber 1 of the travelling-wave tube is located 
outside of the satellite, while the remaining parts of the travelling-wave 
tube are located inside the satellite. The attachment of the electrical 
bushings 4 to the end wall 3 then produces the advantage that these 
bushings 4, which are inserted, vacuum-tight, into the end wall 3, may be 
connected, so as to be electrically conductive, to voltage sources without 
difficulty as regards the inner area of the satellite. 
The described construction of the collector of the travelling-wave tube 
permits the part of the heat to be conducted away by convection by the 
collector electrodes to be increased, and to permit this heat to be 
conducted away over a large area of the outer wall of a cooling chamber. 
The described construction is of particular advantage for travelling-wave 
tubes which are used in satellites, as it allows fastening of the tube to 
satellites in such a manner that the cooling chamber of the collector is 
arranged on the outer side of the satellite and intensive cooling is made 
possible by means of the coldness of outer space. At the same time, a 
simple mounting of the tube is made possible either in or on the 
satellite. 
It will be understood that the above description of the present invention 
is susceptible to various modification changes and adaptations.