EP0178359A1 - Linear beam tubes - Google Patents
Linear beam tubes Download PDFInfo
- Publication number
- EP0178359A1 EP0178359A1 EP84307241A EP84307241A EP0178359A1 EP 0178359 A1 EP0178359 A1 EP 0178359A1 EP 84307241 A EP84307241 A EP 84307241A EP 84307241 A EP84307241 A EP 84307241A EP 0178359 A1 EP0178359 A1 EP 0178359A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- tube
- anode
- end wall
- tubular member
- remote
- 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.)
- Granted
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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
- H01J23/06—Electron or ion guns
Definitions
- the end of member 14 remote from the anode 3 is flanged with its flange 16 attached to the end of the ceramic member remote from the pole piece 4.
Landscapes
- Microwave Tubes (AREA)
Abstract
Description
- This invention relates to linear beam tubes and more particularly to the electron guns of such tubes.
- The electron gun end of a typical linear beam tube is shown in Figure 1 of the accompanying drawings.
- Referring to Figure 1 the glass or ceramic envelope of the linear beam tube is represented at 1; the cathode of its electron gun is represented at 2 and the anode of its electron gun is represented at 3. The anode 3 is mounted directly upon the
first pole piece 4 of a focussing structure at the entrance of a slow wave structure (not represented but to the right as viewed) of the linear beam tube. Commonly but not necessarily thisfirst pole piece 4 constitutes also an end wall of the first cavity of the slow wave structure. In this case the anode 3, mounted as it is on thefirst pole piece 4, is held at ground potential and the length of the main cathode voltage insulator (i.e. the length L of theenvelope 1 electrically between thecathode 2 and the pole piece 4) is determined by the voltage stand-off requirements external to the tube. Where the tube operates in air the length L requires to be longer than would be the case if the gun end of the tube were to be immersed in a dielectric liquid. - With the configuration of Figure 1, during high voltage arcs occurring between the
cathode 2 and anode 3 these electrodes are prone to damage and for this reason the known configuration shown in Figure 2 of the accompanying drawing has found some favour by virtue of the protection that may be afforded to the electrodes in the face of such high voltage arcs. - Referring to Figure 2 in this case the anode electrode 3 is isolated from the
pole piece 4 and is mounted upon ametal cylinder 5 which cylinder is in turn supported between two insulating lengths ofenvelope 1' and 1" which are each of length equal to L. - A
flange 6 by which thecylinder 5 is mounted, and which is sandwiched between the two lengths ofinsulator 1' and 1", forms an electrical connection for the anode 3. Between the electrical connection formed byflange 6 and earth is an external limiting resistor 7. In practice, and as shown, the end of the resistor 7 remote from.theflange 6 is grounded by being attached to thefirst pole piece 4. In some cases grounding is effected not via thefirst pole piece 4 but via a current sensor. - With the construction of Figure 2, during normal operation the anode 3 is held close to ground potential since there is negligible anode current drawn. However when an anode to cathode arc occurs a relatively large current flows through the limiting resistor 7 which charges the anode up to cathode potential, thus causing the arc to be extinguished. In this case the anode is at a potential other than ground potential only during such arcs.
- Whilst the tube illustrated by Figure 2 is, as regards cathode to anode arcs, a "protected" tube as opposed to the tube illustrated by Figure 1 which is an "unprotected" tube, a serious disadvantage arising from the construction of Figure 2 is the added length of insulating envelope wall, i.e. the two
portions 1' and 1", between the cathode mount and the first pole piece 4 - effectively double that of the construction illustrated by Figure 1. Whilst this added length is in itself undesirable there is in consequence also a tendency for the gun to be the more susceptible to vibration. Such vibration can give rise to electrical noise which is a serious limitation in some systems. - The present invention seeks to provide an improved linear beam tube in which the above difficulty is reduced.
- According to this invention an electron beam tube comprises an electron gun having at one end thereof a cathode and at the other end thereof an anode, said anode being mounted adjacent to but isolated from an end wall of a structure downstream of said gun and wherein said anode is supported by means of folded mounting means comprised of a first part extending back from said anode towards the cathode end of said gun and a second part extending forward from the end of said first part remote from said anode towards said end wall, one of said two parts being of insulating material and having provided on a surface thereof a limiting impedance which is electrically in series in a path between said anode and an external termination which in operation may be grounded (directly or indirectly e.g. via a current sensor) whereby to permit said anode to tend to charge towards cathode potential if an anode to cathode arc occurs.
- Said structure may for example be a focussing structure; wave propagating structure; an electron beam tunnel or the like depending upon the type of linear beam tube to which the invention is applied.
- The end of said second part adjacent said end wall may be attached to said end wall or carried from the envelope of said tube at a position adjacent said end wall.
- Commonly said end wall will be the first pole piece of a focussing structure, in which case where the end of said second part adjacent to said end wall is attached to said end wall said pole piece may comprise said external termination.
- Preferably said first and second parts of which said folded mounting means is comprised are, in any plane transverse to the beam axis over the major portions of their lengths, generally circular in cross section and co-axial with said beam axis.
- Both of said parts may overall be generally cylindrical and united at their ends remote from said end wall and said anode by flange means or at least one of said two parts may be generally conical.
- In one embodiment of the invention said first part comprises a ceramic tubular member and said second part comprises a conical metallic member which has a flange at its end remote from said first part which flange extends through the envelope of said tube adjacent said end wall.
- Preferably with a construction as last described said limiting impedance is provided on an internal surface of said tubular member comprising said first part, with one end in contact with said anode and the other in contact with said conical metallic member.
- In another embodiment of the invention said first part comprises a metallic tubular member co- axially within a ceramic tubular member which comprises said second part, said ceramic tubular member being attached at one end to said end wall and the end of said metallic tubular member remote from said anode being flanged with its flange attached to the end of said ceramic tubular member remote from said end wall.
- Preferably with a construction as last described said limiting impedance is provided on an external surface of said tubular member comprising said second part with one end in contact with said flange and the other electrically connected to said external termination.
- Said limiting impedance may comprise deposited resistive material preferably deposited within a groove in the surface of that member upon which said limiting impedance is provided as aforesaid.
- The invention is further described with reference to Figures 3 and 4 of the accompanying drawing which illustrates two embodiments of'i.the present invention.
- In Figures 3 and 4 like references are used for like parts in Figures 1 and 2.
- Referring to Figure 3 as will be seen the anode 3 is isolated from the
pole piece 4 and is mounted upon a ceramiccylindrical member 8 which extends back towards the cathode end of the electron gun. - The cylindrical
ceramic member 8 is supported by means of a flanged conical metallic member 9 which surrounds thecylindrical member 8. Oneend 10 of the conical member 9 is fixed to the end of the cylindricalceramic member 8 remote from the anode 3. The other flanged end of the conical member 9 extends through theenvelope 1 of the tube to form anexternal termination 11. The length of envelope between theflange 11 and the mount of thecathode 2 is equal to L. - On the interior surface of the cylindrical
ceramic member 8 is deposited within agroove 12 resistive material forming the required limiting impedance. The deposited resistive material extends beyond the groove so that oneend 13 of the limiting impedance is in electrical contact with the anode 3 and the other end extends over the end of the cylindricalceramic member 8 to contactend 10 of the conical metallic member 9. As shown, the resistive material is deposited in the base of thegroove 12 and extends only partly up the side walls of the groove. - Thus the limiting impedance is again in series in a path between the anode 3 and the
external termination 11. If this termination is grounded then as already described with reference to Figure 2, arcs occurring between thecathode 2 and the anode 3 may be suppressed. It will be noted however that the overall length of the gun section of the protected tube illustrated by Figure 3 corresponds more closely to that of the electron gun of the unprotected tube of Figure 1 than to the lengthy gun section of the protected tube of Figure 2. - Because the limiting impedance operates in a vacuum within the tube envelope the length of ceramic required to hold off the voltage is less than is the case for the resistor 7 of Figure 2.
- Referring to Figure 4, the anode 3 is again isolated from the
pole piece 4. Anode 3 is mounted upon a generally cylindricalmetallic member 14 which extends back from the anode 3 towards the cathode end of the electron gun. -
Member 14 is co-axially within a cylindricalceramic member 15 which is mounted at one end on thepole piece 4 and extends back therefrom towards the cathode end of the electron gun. - The end of
member 14 remote from the anode 3 is flanged with itsflange 16 attached to the end of the ceramic member remote from thepole piece 4. - Passing through the
envelope wall 1 adjacent to, but spaced from, thepole piece 4 is an annular metallic member 17 which extends inwardly towards the tube axis to contact the cylindricalceramic member 15. Member 17 provides an external termination. - On the exterior surface of cylindrical
ceramic member 15 is deposited within agroove 18, resistive material forming the required limiting impedance. The deposited impedance formed again extends, beyond the groove, from theflange 16 of cylindricalmetallic member 14 to member 17 forming said external termination. - Thus again the limiting impedance is in series in a path between the anode 3 and the external termination formed by member 17 and if the last mentioned is grounded then again as already described with reference to Figure 2 arcs occurring between the
cathode 2 and the anode 3 may be suppressed.
Claims (16)
Priority Applications (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB08320613A GB2144263B (en) | 1983-07-30 | 1983-07-30 | Improvements in or relating to linear beam tubes |
DE8484307241T DE3473376D1 (en) | 1984-10-19 | 1984-10-19 | Linear beam tubes |
AT84307241T ATE36428T1 (en) | 1984-10-19 | 1984-10-19 | LINEAR BEAM TUBES. |
EP19840307241 EP0178359B1 (en) | 1983-07-30 | 1984-10-19 | Linear beam tubes |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB08320613A GB2144263B (en) | 1983-07-30 | 1983-07-30 | Improvements in or relating to linear beam tubes |
EP19840307241 EP0178359B1 (en) | 1983-07-30 | 1984-10-19 | Linear beam tubes |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0178359A1 true EP0178359A1 (en) | 1986-04-23 |
EP0178359B1 EP0178359B1 (en) | 1988-08-10 |
Family
ID=26094354
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP19840307241 Expired EP0178359B1 (en) | 1983-07-30 | 1984-10-19 | Linear beam tubes |
Country Status (2)
Country | Link |
---|---|
EP (1) | EP0178359B1 (en) |
GB (1) | GB2144263B (en) |
Citations (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB655706A (en) * | 1947-10-04 | 1951-08-01 | Philips Nv | Improvements in cathode-ray tubes |
GB872170A (en) * | 1956-11-10 | 1961-07-05 | Ferranti Ltd | Improvements relating to electron-beam discharge tubes |
US3098169A (en) * | 1960-02-08 | 1963-07-16 | English Electric Valve Co Ltd | Travelling wave tubes |
DE1273703B (en) * | 1961-02-10 | 1968-07-25 | Telefunken Patent | Electron beam catcher for run-time tubes, especially runway tubes |
DE1541078A1 (en) * | 1966-07-08 | 1970-01-08 | Telefunken Patent | Electron beam tube with collecting electrode |
GB1199575A (en) * | 1966-12-17 | 1970-07-22 | English Electric Valve Co Ltd | Improvements in or relating to Electron Beam Tubes. |
US3683235A (en) * | 1969-07-18 | 1972-08-08 | Emi Ltd | Electron discharge devices |
US4366415A (en) * | 1979-05-30 | 1982-12-28 | Tokyo Shibaura Denki Kabushiki Kaisha | Picture tube with an electron gun having an improved potential supplying means |
-
1983
- 1983-07-30 GB GB08320613A patent/GB2144263B/en not_active Expired
-
1984
- 1984-10-19 EP EP19840307241 patent/EP0178359B1/en not_active Expired
Patent Citations (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB655706A (en) * | 1947-10-04 | 1951-08-01 | Philips Nv | Improvements in cathode-ray tubes |
GB872170A (en) * | 1956-11-10 | 1961-07-05 | Ferranti Ltd | Improvements relating to electron-beam discharge tubes |
US3098169A (en) * | 1960-02-08 | 1963-07-16 | English Electric Valve Co Ltd | Travelling wave tubes |
DE1273703B (en) * | 1961-02-10 | 1968-07-25 | Telefunken Patent | Electron beam catcher for run-time tubes, especially runway tubes |
DE1541078A1 (en) * | 1966-07-08 | 1970-01-08 | Telefunken Patent | Electron beam tube with collecting electrode |
GB1199575A (en) * | 1966-12-17 | 1970-07-22 | English Electric Valve Co Ltd | Improvements in or relating to Electron Beam Tubes. |
US3683235A (en) * | 1969-07-18 | 1972-08-08 | Emi Ltd | Electron discharge devices |
US4366415A (en) * | 1979-05-30 | 1982-12-28 | Tokyo Shibaura Denki Kabushiki Kaisha | Picture tube with an electron gun having an improved potential supplying means |
Non-Patent Citations (2)
Title |
---|
IEEE TRANSACTIONS ON CONSUMER ELECTRONICS, vol. CE-26, no. 3, August 1980, pages 446-451, New York, US; Y. KOBORI et al.: "A novel arc-suppression technique for cathode ray tubes" * |
PATENTS ABSTRACTS OF JAPAN, vol. 6, no. 222 (E-140)[1100], 6th November 1982; & JP - A - 57 124 835 (NIPPON DENKI K.K.) 03-08-1982 * |
Also Published As
Publication number | Publication date |
---|---|
EP0178359B1 (en) | 1988-08-10 |
GB2144263A (en) | 1985-02-27 |
GB2144263B (en) | 1986-10-29 |
GB8320613D0 (en) | 1983-09-01 |
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