US3644769A

US3644769A - Cooling arrangements for valves

Info

Publication number: US3644769A
Application number: US71136A
Authority: US
Inventors: Matthew Campbell Kennedy
Original assignee: English Electric Valve Co Ltd
Current assignee: Teledyne UK Ltd
Priority date: 1969-09-12
Filing date: 1970-09-10
Publication date: 1972-02-22
Anticipated expiration: 1989-02-22
Also published as: DE2045097A1; FR2061323A5; GB1276915A; DE2045097B2

Abstract

An arrangement for cooling the collector of a travelling wave tube includes a heat sink which is connected via good thermally conductive collets to the collector. The collet comprises a collet jaw, which is in close contact with the collector, and an adjustable collet shoe which is slidably situated between the collet jaw and the heat sink. The arrangement allows lateral and angular displacement of the collector relative to the heat sink without degradation of the heat transfer properties.

Description

[s 1 COOLHNG Aamomwwrs so VALVES 72 Inventor: tthew Campbell Kennedy, Chelm'sford,

England V {73] Assignee: English Electric VaiveCompany Limited,

London, England [22] Filed: Sept. 10, 1970 21 Appl. No.: 71,136

[30] Foreign Application Priority Data Sept. 12, 1969 Great Britain ..45,047/69 52] U.S.Cl. .;..3113/46 [51] lint. Cl ...lillilllj 25/00 [58] lField oiScarcli ..3l3/46 [56] References Cited UNITED STATES PATENTS 3,553,952 1/1971 Forbes .,,....313/46 Primary Examiner-Roy Lake Assistant Examiner-Darwin R. Hostetter Attorney-Baldwin, Wight and Brown the heat sink without degradation of the heat transfer properties.

a claims, 1 Hm COOLING ARRANGEMENTS FOR VALVES This invention relates to cooling arrangements for valves and more particularly to arrangements for the conduction cooling of the collectors of travelling wave tubes.

It is frequently desirable to cool the collector of a travelling wave tube which is operating at an input power level greater than a few watts. I

One method which has been used to provide suitable cooling in such cases consists of providing a heat conduction block which is attached to one end of the travelling wave tube focusing mount. This block, within which the travelling wave tube is located, serves to conduct the heat from the collector and the block may be attached to an external radiator of adequate dimensions for the heat to be removed therefrom by natural convection. This arrangement is a satisfactory one provided the travelling wave tube and its focusing mount are supplied as an integral package, for in this case the collector may be accurately and permanently aligned with the focusing mount when' the block is secured to the focusing mount during final assembly of the components. However in most applications it is preferred that the travelling wave tube be replaceable within its mount in situ, because such tubes have a limited operating life. This avoids the need to disconnect waveguide connections and power supply leads to the mount when the travelling wave tube needs to be replaced.

Interchangeability of the travelling wave tube with its mount imposes special conditions on the design and construction of the block which must be such as to allow a quick, simple and easy insertion and removal of the tube to reduce the possibility of damage to the tube during handling and to minimize the time during which the equipment is not in operation. In addition means must be provided for positioning the travelling wave tube accurately with respect to its focusing mount. it is desirable to align the travelling wave tube accurately with the focusing mount, since this makes a reduction in operating helix current possible (the common form of travelling wave tube in which the slow wave circuit is a helix is, for the moment, assumed), thereby prolonging the life of the travelling wave tube by reducing its operating temperature. The provision for fine adjustment of the tube position is also desirable because it permits some relaxation of the alignment requirements of the internal tube electrodes during manufacture, which are in any case severe.

The object of this invention is to provide, for a travelling wave tube, a cooling arrangement which whilst providing efficient cooling allows adjustment of position of the travelling wave tube.

According to this invention a cooling arrangement for the collector of a travelling wave tube includes a block of material of good thermal conductivity, containing an aperture into which the collector may be inserted, and a plurality of collet members arranged to grip the collector when it is positioned in the aperture, the collet members each being made of material of good thermal conductivity and each having a first part which is in said aperture and which abuts the collector, the abutting surface thereof being shaped so as to mate with said collector surface, and a second part which is positioned in a groove or channel in said block such that it is in good thermal contact with said block and the first and second collet member parts having flat mating surfaces so as to allow sliding contact therebetween.

if the mode of adjustment that is required for the travelling wave tube requires both lateral and angular movements thereof then the arrangement should employ two or preferably four collet members. If, however, solely lateral movement is required then the number of collet members used may depart from two or four members.

Preferably the collet members are urged inwardly towards the aperture by means of springs under tension, the ends of a spring being attached to two different collet members.

By a material of good thermal conductivity is intended a material, such as a metal, whose thermal conductivity is significantly higher than that of air. Similarly the expression good thermal contact" is intended to mean contact such as to provide thermal conduction substantially greater than that which occurs through air. A wide choice exists as regards the material for the thermally conductive elements. Copper and brass are materials which have been used experimentally with very successful results. if a metal is used to assist thermal conduction through the system the sliding interfaces may with advantage be smeared with a good thennally conductive oil or thin grease, which will act also as a lubricant. The lubricant should preferably not be permitted to come into contact with the travelling wave tube itself.

The invention is illustrated in and further described by way of example with reference to the accompanying drawing in which is shown a diagrammatic end view of one cooling arrangement in accordance with this invention.

Referring to the drawing, there is shown a collector l of a travelling wave tube, the collector being of cylindrical form and shown positioned in the center of an aperture 8 in a block 7. In thermal contact with the collector are four collet members made of good thermally conductive material and having a first part, or collet jaw 2 so arranged and shaped as to encircle the collector l, but with a small gap between any one collet jaw and adjacent collet jaws, to allow each collet jaw to seat properly in contact with the collector 1. The collet jaws 2 are each in good thermal contact with a movable second part 3 of the collet member, said second part 3 being a collet shoe. To

maintain the collet jaws 2 in close contact with the collector l a peg 4 is inserted in each end face of each collet shoe 3 and a spring 5 in tension attached between each adjacent pair of pegs 4. Each collet shoe 3 is a close sliding fit within a groove or channel 6 within the body of 'the block 7 of good thermally conductive material. The block 7 in practice is secured to a travelling wave tube focusing mount (not shown) and may have suitable external finning (not shown) to assist heat dissipation to its surroundings. The collet shoes 3 have means (not shown) for having their position adjusted in the grooves or channels 6, and by these means adjustment of the lateral position and angular orientation of the collector 1 within the aperture 8 relative to the good thermally conductive block 7,

and hence the focusing mount, may be effected.

Other arrangements according to this invention may also be used, for example an arrangement using only two collet jaws which bear on opposite sides of the curved collector surface. In this case the surface of the collet jaw in contact with the collector would encircle nearly half of the circumference of the collector, and as in the previous embodiment each collet jaw would be in good thermal contact with a movable collet shoe.

The choice of the number of collet members used is not restricted to two or four. However, both angular and translational movement of the collector with respect to the block are attainable only with arrangements using either two of four collet jaws. With other arrangements, for example one using three collet jaws, where each jaw would encircle approximately one-third of thecircumference of the collector, the angular movement is not satisfactorily achievable and only translational movement is possible whilst maintaining good thermal contact between the collet jaws and the travelling wave tube collector.

I claim:

1. A cooling arrangement for the collector of a travelling wave tube said arrangement including a block of material of good thermal conductivity, containing an aperture into which the collector may be inserted, and a plurality of collet members arranged to grip the collector when it is positioned in the aperture, the collet members each being made of material of good thermal conductivity and each having a first part which is in said aperture and which abuts the collector, the abutting surface thereof being shaped so as to mate with said collector surface, and a second part which is positioned in a groove or channel in said block such that it is in good thermal contact with said block and the first and second collet member parts having flat mating surfaces so as to allow sliding contact therebetween.

2. An arrangement as claimed in claim 1 wherein there are two collet members.

3. An arrangement as claimed in claim 1 wherein there are four collet members.

4. An arrangement as claimed in claim 1 wherein the collet 5 members are urged inwardly towards the aperture by means of springs under tension, the ends of a spring being attached to two different collet members.

Claims

2. An arrangement as claimed in claim 1 wherein there are two collet members.

3. An arrangement as claimed in claim 1 wherein there are four collet members.

4. An arrangement as claimed in claim 1 wherein the collet members are urged inwardly towards the aperture by means of springs under tension, the ends of a spring being attached to two different collet members.