GB2045518A - Travelling wave tube collectors - Google Patents
Travelling wave tube collectors Download PDFInfo
- Publication number
- GB2045518A GB2045518A GB7910164A GB7910164A GB2045518A GB 2045518 A GB2045518 A GB 2045518A GB 7910164 A GB7910164 A GB 7910164A GB 7910164 A GB7910164 A GB 7910164A GB 2045518 A GB2045518 A GB 2045518A
- Authority
- GB
- United Kingdom
- Prior art keywords
- tube
- shell
- travelling wave
- collector
- collector electrode
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J23/00—Details of transit-time tubes of the types covered by group H01J25/00
- H01J23/02—Electrodes; Magnetic control means; Screens
- H01J23/027—Collectors
Abstract
A travelling wave tube collector electrode 1 has, mounted within it in an insulating manner, a shell of pyrolitic graphite 3 which may be biassed separately from the outer body of the collector in order to provide operation in "depressed collector" mode. In a modification (Fig. 2, not shown) the shell is provided in two or more sections electrically insulated one from another each of which sections may be individually biassed to provide operation in "multiple collector depression" mode. <IMAGE>
Description
SPECIFICATION
Improvements in or relating to electron beam tubes
This invention relates to electron beam tubes and in particular to high power electron beam tubes, such as klystrons and travelling wave tubes of the kind having a hollow collector electrode provided to collect residual electrons from a beam passing through the tube following the extraction of high frequency energy therefrom.
In order to improve the overall efficiency of such tubes the power supplies are commonly arranged so that the collector electrode runs at a negative potential with respect to the main body of the tube so that the residual electrons are slowed as they enter the interior of the collector electrode. Such provision results in what is known as "depressed collector operation". As a result of this the residual electrons entering the collector elelctrode have a range of velocities and in order to provide further improvements in efficiency it is known to divide the collector electrode into a number of sections each of which is arranged to run at a different potential so that residual electrons of different energies are collected at appropriate potentials. Such provision results in what is called "multiple collector depression" operation.
The effectiveness of the collector electrode in all cases tends to be limited by the fact that secondary electrons and high energy reflected electrons tend to be produced at the interior surface of the collector electrode due to the incident electrons. These spurious electrons are usually referred to as "back scattered electrons" and it is often found that these are focused back down the main body of the tube resulting in an undesirably modified performance or are accelerated from the collector electrode to another part of the tube and so limit the improvement in efficiency that can be obtained.
One object of the present invention is to provide an improved high power electron beam tube of the kind referred to in which the numbers of back scattered electrons from the hollow collector electrode tend to be reduced.
According to this invention a travelling wave tube of the kind referred to is provided wherein the interior of said holllow collector electrode is provided with a lining of energy absorbent material which is of low secondary emission co-effecient in the range of incident energies and resistant to the effects of heat.
Preferably said lining comprises a shell of pyrolitic graphite material mounted within an outer body of said hollow collector electrode.
Preferably said shell of pyrolitic graphite material is mounted in electrically insulating manner within said outer body of said hollow collector electrode and means are provided for applying separate bias potential thereto whereby said tube may be operated in "depressed collector" mode.
In a modification of the above said shell is provided in two or more sections electrically insulated one from another and each having means for providing an individual bias potential thereto whereby said tube may be operated in "multiple collector depression" mode.
The invention is illustrated in and further described with reference to the accompanying drawings in which
Figure 1 illustrates the hollow collector electrode of a typical klystron tube provided for depressed collector operation and in accordance with the present invention, and
Figure 2 illustrates the hollow collector electrode of a typical klystron tube provided for multiple collector depression operation and in accordance with the present invention.
Referring to Fig. 1 the collector electrode consists of a hollow copper body 1 having an entrance 2 which faces the electron gun (not shown) of the tube. In operation residual electrons from the beam after the extraction of high frequency energy enter the body 1 via the entrance 2.
Within the body 1 is provided a thin cylindrical shell 3 of pyrolitic graphite material.
The shell 3 is closed except for its mouth 4 which encompasses the entrance 2 of the body 1 so that residual electrons passing through entrance 2 are collected within the shell 3. The interior surface 5 of the shell 3 is roughened by etching in order to improve its efficiency as a collector.
The shell 3 is spaced from the body 1 by means of an insulator of alumina or sapphire as diagrammatically represented at 6.
The shell 3 by virtue of the insulators 6 may be held at a suitable negative voltage with respect to the body 1 in order to achieve depressed collector operation. The electrical connection for this purpose is provided for by lead 7 passing via an insulating "feedthrough" in the wall of the body 1.
In impinging on the inner surface of the shell 3 the residual electrons will dissipate their energy whilst producing few back scattered electrons because of the low secondary emission co-efficient of pyrolitic graphite (less than 1 for a wide range of incident energies).
Shell 3 will however run at high temperature (e.g. 1 500K) and this is cooled by radiation to the outer body 1 which is itself cooled by conventional means (not shown) such as liquid cooling, vapour cooling or conduction to another cooled surface.
Referring to Fig. 2 it is believed that the collector electrode illustrated therein will be largely self-explanatory having regard to the description already given with respect to Fig.
1. Instead of the single inner pyrolitic graphite shell 3 a number, in this case three, of sections referenced 3.a., 3.b. and 3.c are provided each of which may be held at a different negative voltage as appropriate for multiple collector depression operation. Section 3.a. is connected to a lead 7.a. passing through a "feed-through" 8.a.; section 3.b. is connected to a lead 7.b. passing through a feed-through 8.b. and section 3.c. is connected to a lead 7.c. passing through a feedthrough 8.c.
It will be noted that one advantage of a tube in accordance with the present invention is that even when the tube is arranged for depressed collector operation or multiple col
lector depression operation the outer body 1 of the collector electrode may be run at earth potential. Thus where liquid cooling is in question the difficulty of providing coolant channels with high voltages there-across and the associated problems of electrical breakdown in the coolant liquid may be avoided. If conduction cooling is in question, again because the outer body 1 may be run at each potential, greater efficiency may be obtained since no insulation is required.
Claims (6)
1. A travelling wave tube of the kind referred to wherein the interior of said hollow collector electrode is provided with a lining of energy absorbent material which is of low secondary emission co-efficient in the range of incident energies and resistant to the effects of heat.
2. A tube as claimed in claim 1 and wherein said lining comprises a shell of pyrolitic graphite material mounted within an outer body of said hollow collector electrode.
3. A tube as claimed in claim 2 and wherein said shell of pyrolitic graphite material is mounted in electrically insulating manner within said outer body of said hollow collector and means are provided for applying separate bias potential thereto whereby said tube may be operated in "depressed collec tor mode.
4. A tube as claimed in claim 2 and wherein said shell is provided in two or more sections electrically insulated one from another and each having means for providing an individual bias potential thereto whereby said tube may be operated in "multiple collector depression" mode.
5. A travelling wave tube of the kind referred to substantially as herein described with reference to Fig. 1 of the accompanying drawings.
6. A travelling wave tube of the kind referred to substantially as herein described with reference to Fig. 2 of the accompanying drawings.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB7910164A GB2045518A (en) | 1979-03-22 | 1979-03-22 | Travelling wave tube collectors |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB7910164A GB2045518A (en) | 1979-03-22 | 1979-03-22 | Travelling wave tube collectors |
Publications (1)
Publication Number | Publication Date |
---|---|
GB2045518A true GB2045518A (en) | 1980-10-29 |
Family
ID=10504068
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
GB7910164A Withdrawn GB2045518A (en) | 1979-03-22 | 1979-03-22 | Travelling wave tube collectors |
Country Status (1)
Country | Link |
---|---|
GB (1) | GB2045518A (en) |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0113907A1 (en) * | 1982-12-21 | 1984-07-25 | Max-Planck-Gesellschaft zur Förderung der Wissenschaften e.V. | Layer preventing disturbances created by secondary-electron emission, and manufacture of such a layer |
DE4033101A1 (en) * | 1990-10-18 | 1992-04-23 | Licentia Gmbh | Electron collector for HF electron tube - produces asymmetrical electric field in collector which is easily adjustable |
GB2340990A (en) * | 1998-08-25 | 2000-03-01 | Finnigan Mat Gmbh | Faraday cup having graphite walls |
CN102074438B (en) * | 2009-11-25 | 2012-09-26 | 中国科学院电子学研究所 | Graphite composite multistage depressed collector and manufacturing method thereof |
-
1979
- 1979-03-22 GB GB7910164A patent/GB2045518A/en not_active Withdrawn
Cited By (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0113907A1 (en) * | 1982-12-21 | 1984-07-25 | Max-Planck-Gesellschaft zur Förderung der Wissenschaften e.V. | Layer preventing disturbances created by secondary-electron emission, and manufacture of such a layer |
DE4033101A1 (en) * | 1990-10-18 | 1992-04-23 | Licentia Gmbh | Electron collector for HF electron tube - produces asymmetrical electric field in collector which is easily adjustable |
GB2340990A (en) * | 1998-08-25 | 2000-03-01 | Finnigan Mat Gmbh | Faraday cup having graphite walls |
US6452165B1 (en) | 1998-08-25 | 2002-09-17 | Finnigan Mat Gmbh | Faraday collector for measuring ion currents in mass spectrometers |
GB2340990B (en) * | 1998-08-25 | 2003-01-22 | Finnigan Mat Gmbh | Faraday collector for measuring ion currents in mass spectrometers |
DE19838553B4 (en) * | 1998-08-25 | 2010-08-12 | Thermo Fisher Scientific (Bremen) Gmbh | Faraday collector for measuring ion currents in mass spectrometers |
CN102074438B (en) * | 2009-11-25 | 2012-09-26 | 中国科学院电子学研究所 | Graphite composite multistage depressed collector and manufacturing method thereof |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |