US3070550A - Cathodes for electron tubes - Google Patents
Cathodes for electron tubes Download PDFInfo
- Publication number
- US3070550A US3070550A US9182A US918260A US3070550A US 3070550 A US3070550 A US 3070550A US 9182 A US9182 A US 9182A US 918260 A US918260 A US 918260A US 3070550 A US3070550 A US 3070550A
- Authority
- US
- United States
- Prior art keywords
- cathodes
- oxide
- electron tubes
- tubes
- electron
- 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.)
- Expired - Lifetime
Links
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J1/00—Details of electrodes, of magnetic control means, of screens, or of the mounting or spacing thereof, common to two or more basic types of discharge tubes or lamps
- H01J1/02—Main electrodes
- H01J1/13—Solid thermionic cathodes
- H01J1/14—Solid thermionic cathodes characterised by the material
Definitions
- This invention relates to cathodes for electron tubes which have a high efficiency of electron emission at compartively low temperature.
- cathodes for electron tubes which consist of porous metals containing oxide mixtures of two or more ingredients such a barium oxide, aluminum oxide, calcium oxide, magnesium oxide and strontium oxide
- the melting points of the oxide mixtures are generally above 1300 C. and as high as 1700 C. Therefore, an excessively high temperature is required for impregnation, which makes the manufacturing of cathodes difiicult.
- the heating temperature for such cathodes must be raised to at least 1100 C. in order to obtain sufiicient electron emission. Consequently, the life of heating filaments for cathodes is shortened, the cathodes deform more readily, and surrounding electrodes surrounding the cathodes, are spattered by material emitted by the cathode.
- oxide mixtures of barium oxide, beryllium oxide and calcium oxide as shown in the following table are melted in a hydrogen furnace, coagulated, crushed and then impregnated into tungsten or other heat resisting porous metals in vacuum or at- "ice mospheres of hydrogen, argon, etc. at such melting temperatures as shown in the table:
- the melting temperatures are lower than those of conventional oxide mixtures and temperatures for activation in vacuum may be limited so as not to exceed 1030 C., which greatly facilitates the manufacturing of cathodes.
- the cathodes made in accordance with the present invention will emit sufficient electrons as shown in the table.
- the life of heating filaments is materially extended, the cathode-supporting metals will not deform, and the electrodes surrounding the cathode will not be spattered. Therefore, the cathodes according to this invention are superior to known cathodes when used for electron tubes as they afford long-life and high reliability to the tubes.
- the cathode impregnated with the mixture of 2 mols of barium oxide, 1 mol of beryllium oxide and 1 mol of calcium oxide emit an electron emission of 9.6 amperes per sq. cm. and afiords stable operation during continuous operation of 1,500 hours or more.
- Cathodes for electron tubes comprising heat-resisting porous metals impregnated with oxide mixtures of barium oxide, beryllium oxide and calcium oxide in mixture proportions of 2 to 3 mols, 1 to 2 mols and V2 to 1 mol respectively.
Landscapes
- Solid Thermionic Cathode (AREA)
Description
United States Patent 3,070,550 CATHQDES FOR ELECTRON TUBES Saburo Aoi and Noboru Murata, Tokyo, Japan, assignors to Oki Electric Industry Company, Ltd., Tokyo, Japan,
a corporation of Japan No Drawing. Filed Feb. 17, 1960, Ser. No. 9,182 Claims priority, application Japan Feb. 25, 1959 1 Claim. (Cl. 252-621) This invention relates to cathodes for electron tubes which have a high efficiency of electron emission at compartively low temperature.
It is an object of the invention to provide cathodes for electron tubes which can emit suificient electrons without raising the heating temperature excessively.
It is another object of the invention to provide an improved cathode for electron tubes which will not become deformed and will not spatter electrodes surrounding the cathode.
It is a further object of the invention to provide a low melting point oxide mixture for cathodes to reduce the temperature for activation in vacuum in the manufacturing process of cathodes.
In conventional cathodes for electron tubes which consist of porous metals containing oxide mixtures of two or more ingredients such a barium oxide, aluminum oxide, calcium oxide, magnesium oxide and strontium oxide, the melting points of the oxide mixtures are generally above 1300 C. and as high as 1700 C. Therefore, an excessively high temperature is required for impregnation, which makes the manufacturing of cathodes difiicult. Furthermore, since the efficiency of electron emission at 1000 C. is inferior, the heating temperature for such cathodes must be raised to at least 1100 C. in order to obtain sufiicient electron emission. Consequently, the life of heating filaments for cathodes is shortened, the cathodes deform more readily, and surrounding electrodes surrounding the cathodes, are spattered by material emitted by the cathode.
According to this invention, oxide mixtures of barium oxide, beryllium oxide and calcium oxide as shown in the following table are melted in a hydrogen furnace, coagulated, crushed and then impregnated into tungsten or other heat resisting porous metals in vacuum or at- "ice mospheres of hydrogen, argon, etc. at such melting temperatures as shown in the table:
As seen on the above table, the melting temperatures are lower than those of conventional oxide mixtures and temperatures for activation in vacuum may be limited so as not to exceed 1030 C., which greatly facilitates the manufacturing of cathodes. The cathodes made in accordance with the present invention will emit sufficient electrons as shown in the table. Moreover, in these cathodes the life of heating filaments is materially extended, the cathode-supporting metals will not deform, and the electrodes surrounding the cathode will not be spattered. Therefore, the cathodes according to this invention are superior to known cathodes when used for electron tubes as they afford long-life and high reliability to the tubes. These advantages are important in electron tubes generally and are particularly important in high power tubes such as microwave magnetrons and the like. For instance, the cathode impregnated with the mixture of 2 mols of barium oxide, 1 mol of beryllium oxide and 1 mol of calcium oxide emit an electron emission of 9.6 amperes per sq. cm. and afiords stable operation during continuous operation of 1,500 hours or more.
What is claimed is:
Cathodes for electron tubes comprising heat-resisting porous metals impregnated with oxide mixtures of barium oxide, beryllium oxide and calcium oxide in mixture proportions of 2 to 3 mols, 1 to 2 mols and V2 to 1 mol respectively.
References Cited in the file of this patent UNITED STATES PATENTS 2,902,621 Winter Sept. 1, 1959
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3070550X | 1959-02-25 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| US3070550A true US3070550A (en) | 1962-12-25 |
Family
ID=17964504
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| US9182A Expired - Lifetime US3070550A (en) | 1959-02-25 | 1960-02-17 | Cathodes for electron tubes |
Country Status (1)
| Country | Link |
|---|---|
| US (1) | US3070550A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3656020A (en) * | 1970-11-18 | 1972-04-11 | Spectra Mat Inc | Thermionic cathode comprising mixture of barium oxide, calcium oxide and lithium oxide |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2902621A (en) * | 1953-03-04 | 1959-09-01 | Egyesuelt Izzolampa | Supply cathode |
-
1960
- 1960-02-17 US US9182A patent/US3070550A/en not_active Expired - Lifetime
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2902621A (en) * | 1953-03-04 | 1959-09-01 | Egyesuelt Izzolampa | Supply cathode |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3656020A (en) * | 1970-11-18 | 1972-04-11 | Spectra Mat Inc | Thermionic cathode comprising mixture of barium oxide, calcium oxide and lithium oxide |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| EP0179513B1 (en) | Method of manufacturing a scandate dispenser cathode and dispenser cathode manufactured by means of the method | |
| US2492142A (en) | Electric system embodying coldcathode gaseous discharge device | |
| US2639399A (en) | Electron emitter | |
| US2173259A (en) | Active metal compounds for vacuum tubes | |
| US3070550A (en) | Cathodes for electron tubes | |
| US3029359A (en) | Thermionic electrode for discharge lamps | |
| US1992566A (en) | Fixation of atmospheric nitrogen by means of an electric arc | |
| US2185410A (en) | Metal compositions | |
| US1552310A (en) | Electrode for discharge tubes | |
| US2012237A (en) | Cathode | |
| US4265666A (en) | Boron carbide La, Sr and/or Ba hexaboride ceramic material for a low temperature direct heating electric gun cathode | |
| US1981245A (en) | Space-current device | |
| US2029144A (en) | Electric discharge device or vacuum tube | |
| US1749780A (en) | Incandescent-cathode device | |
| US3069580A (en) | Fluorescent lamp | |
| US2106855A (en) | Space-current device | |
| US2527984A (en) | Method of manufacturing electric discharge tubes | |
| US2172968A (en) | Electric discharge tube | |
| US1747063A (en) | Electrode composition for electron-discharge devices | |
| US2394095A (en) | Activated electrode | |
| US1663553A (en) | Electron-emitting material | |
| US1731244A (en) | Electron-emitting material and method of making the same | |
| US3242374A (en) | Cold cathode with nickel base, calcium oxide interface and magnesium oxide layer | |
| US2131909A (en) | Alloy | |
| US2871196A (en) | Cathodes and emissive material therefor |