US2867742A - Dispenser cathode - Google Patents
Dispenser cathode Download PDFInfo
- Publication number
- US2867742A US2867742A US411222A US41122254A US2867742A US 2867742 A US2867742 A US 2867742A US 411222 A US411222 A US 411222A US 41122254 A US41122254 A US 41122254A US 2867742 A US2867742 A US 2867742A
- Authority
- US
- United States
- Prior art keywords
- cavity
- cathode
- alkaline
- dispenser
- supply
- 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
- 229910000287 alkaline earth metal oxide Inorganic materials 0.000 claims description 7
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 claims description 4
- 239000003870 refractory metal Substances 0.000 claims description 4
- 238000004519 manufacturing process Methods 0.000 claims description 3
- 239000000203 mixture Substances 0.000 claims description 3
- 238000005245 sintering Methods 0.000 claims description 2
- 239000007789 gas Substances 0.000 claims 2
- 230000001427 coherent effect Effects 0.000 claims 1
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 7
- 229910052750 molybdenum Inorganic materials 0.000 description 7
- 239000011733 molybdenum Substances 0.000 description 7
- 238000000034 method Methods 0.000 description 6
- 150000004649 carbonic acid derivatives Chemical class 0.000 description 5
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 5
- 229910052721 tungsten Inorganic materials 0.000 description 5
- 239000010937 tungsten Substances 0.000 description 5
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 4
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 4
- 238000010438 heat treatment Methods 0.000 description 3
- 235000010603 pastilles Nutrition 0.000 description 3
- 239000011148 porous material Substances 0.000 description 3
- 150000001341 alkaline earth metal compounds Chemical class 0.000 description 2
- 229910002092 carbon dioxide Inorganic materials 0.000 description 2
- 239000001569 carbon dioxide Substances 0.000 description 2
- 230000008020 evaporation Effects 0.000 description 2
- 238000001704 evaporation Methods 0.000 description 2
- 229910052735 hafnium Inorganic materials 0.000 description 2
- VBJZVLUMGGDVMO-UHFFFAOYSA-N hafnium atom Chemical compound [Hf] VBJZVLUMGGDVMO-UHFFFAOYSA-N 0.000 description 2
- BDAGIHXWWSANSR-NJFSPNSNSA-N hydroxyformaldehyde Chemical compound O[14CH]=O BDAGIHXWWSANSR-NJFSPNSNSA-N 0.000 description 2
- 229910052758 niobium Inorganic materials 0.000 description 2
- 239000010955 niobium Substances 0.000 description 2
- GUCVJGMIXFAOAE-UHFFFAOYSA-N niobium atom Chemical compound [Nb] GUCVJGMIXFAOAE-UHFFFAOYSA-N 0.000 description 2
- 229910052697 platinum Inorganic materials 0.000 description 2
- 238000001556 precipitation Methods 0.000 description 2
- 229910000018 strontium carbonate Inorganic materials 0.000 description 2
- NEDFZELJKGZAQF-UHFFFAOYSA-J strontium;barium(2+);dicarbonate Chemical compound [Sr+2].[Ba+2].[O-]C([O-])=O.[O-]C([O-])=O NEDFZELJKGZAQF-UHFFFAOYSA-J 0.000 description 2
- 238000003466 welding Methods 0.000 description 2
- 229910052784 alkaline earth metal Inorganic materials 0.000 description 1
- 150000001342 alkaline earth metals Chemical class 0.000 description 1
- 229910052788 barium Inorganic materials 0.000 description 1
- DSAJWYNOEDNPEQ-UHFFFAOYSA-N barium atom Chemical compound [Ba] DSAJWYNOEDNPEQ-UHFFFAOYSA-N 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 230000008602 contraction Effects 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- -1 ltantalum Chemical compound 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- 229910052715 tantalum Inorganic materials 0.000 description 1
- GUVRBAGPIYLISA-UHFFFAOYSA-N tantalum atom Chemical compound [Ta] GUVRBAGPIYLISA-UHFFFAOYSA-N 0.000 description 1
Images
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
- H01J1/20—Cathodes heated indirectly by an electric current; Cathodes heated by electron or ion bombardment
- H01J1/28—Dispenser-type cathodes, e.g. L-cathode
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J9/00—Apparatus or processes specially adapted for the manufacture, installation, removal, maintenance of electric discharge tubes, discharge lamps, or parts thereof; Recovery of material from discharge tubes or lamps
- H01J9/02—Manufacture of electrodes or electrode systems
- H01J9/04—Manufacture of electrodes or electrode systems of thermionic cathodes
- H01J9/042—Manufacture, activation of the emissive part
- H01J9/047—Cathodes having impregnated bodies
Definitions
- This invention relates to a dispenser cathode having a cavity which contains a supply of alkaline-earth metal compounds, the wall of the cavity being constituted in part by a porous body of one of the refractory metals tungsten, molybdenum, tantalum, 'hafnium or niobium, which body has been sintered at a high temperature and the pores of which constitute the largest apertures in the wall of the cavity.
- the invention furthermore relates to a method of manufacturing such a cathode.
- the supply in a dispenser cathode having a cavity which contains a supply of alkaline-earth metal compounds and of which the wall is constituted n part by a porous body of one of the refractory metals tungsten, molybdenum, ltantalum, hafnium or niobium, which body has been sintered at a high temperature and the pores yof which constitute the largest apertures in the wall of the cavity, the supply consists of a compact mass of alkaline-earth oxide which has been sintered together.
- the sintered compact mass of alkaline-earth oxide may be obtained by pressing alkaline-earth carbonate and subsequently heating it for some time in a vacuum oven or in an indiierent atmosphere at a high temperature.
- the heating may be effected either in a Crucible of any suitable metal, for example platinum, or in the cavity of the dispenser cathode itself before being closed by the porous body, which cavity is formed, for example, by
- reference number 7 indicates a cylindrical molybdenum body having a at flange 8 which is engaged by a porous tungsten body 9, a at ange 10 of a molybdenum cylinder 11 engaging the' other side of the tungsten body.
- the cavity between the body 9 and the cylindrical body 7 contains a supply of alkaline-earth oxide, indicated by 12, which is obtained by precipitation in a compact form. The precipitation is followed by heating in the same manner as in the case of the pressed carbonate shown in Fig. l. It is alternatively possible for a ymass of alkaline-earth carbonate of the desired shape to be heated in a vacuum oven and provided around the body 7.
Description
Jan. 6, 1959 H. J. LEMMENS ETAL DISPENSER CATHODE Filed Feb. 18. 1954 INVENTORS v HENDRIKUS JOHANNES LEMMENS MARINUS JACObUS JANSEN PIETER WILLEM HAAYMAN BY i AGENT lPatent 2,867,742 .Patented Jan. `@1959 Y Y- DISPENSER v*(iA'TIroDE Application February 18, 1954, Serial No. 411,222
Claims priority, application Netherlands February 26, 1953 4 Claims. (Cl. 313-346) This invention relates to a dispenser cathode having a cavity which contains a supply of alkaline-earth metal compounds, the wall of the cavity being constituted in part by a porous body of one of the refractory metals tungsten, molybdenum, tantalum, 'hafnium or niobium, which body has been sintered at a high temperature and the pores of which constitute the largest apertures in the wall of the cavity. The invention furthermore relates to a method of manufacturing such a cathode.
Dispenser cathodes of the above-mentioned kind are known for their favourable properties in regard to life and emission and also for the easy workability of t-he emission surface into the desired shape. The lling of the cavity in the dispenser cathode consists of carbonates which are disintegrated into oxides during the exhaustion of the discharge tube.
More particularly for cathodes intended for working temperatures higher than 1200a C. it is desirable that the porous body should have a low porosity in order to limit the evaporation of barium. However, a low porosity involves the disadvantage that the carbon dioxide developed during the disintegration of the carbonates exhibits a comparatively high pressure in the cavity and nevertheless escapes only slowly. At'the high temperatures occurring, the carbon dioxide can cause oxidation of the porous body or other parts of the wall of the cavity, so that the formation of free alkaline-earth metal may be impeded, whilst furthermore other unpleasant phenomena may be involved.
The object of the invention is to provide a cathode which does not exhibit the above-mentioned disadvantages.
According to the invention, in a dispenser cathode having a cavity which contains a supply of alkaline-earth metal compounds and of which the wall is constituted n part by a porous body of one of the refractory metals tungsten, molybdenum, ltantalum, hafnium or niobium, which body has been sintered at a high temperature and the pores yof which constitute the largest apertures in the wall of the cavity, the supply consists of a compact mass of alkaline-earth oxide which has been sintered together.
The sintered compact mass of alkaline-earth oxide may be obtained by pressing alkaline-earth carbonate and subsequently heating it for some time in a vacuum oven or in an indiierent atmosphere at a high temperature. The heating may be effected either in a Crucible of any suitable metal, for example platinum, or in the cavity of the dispenser cathode itself before being closed by the porous body, which cavity is formed, for example, by
,a molybdenum body, but in this case it is desirable that .the carbonates should be disintegrated at a comparatively low temperature, whichmaybe followed by sinter- '.''ing' together atfaJ-hig'heritemperature. rThe question as to whether it is necessarytof--worky'in vacuo or'vin an findii'erentsfatmospheres is Y :dependent inter alia r upon the pressure that is used and the resultant time required for compact sintering in connection with evaporation of the oxides.
The compact mass of alkaline-earth oxide which has been sintered together is comparatively well resistant to air, so that it can `be worked in dispenser cathodes in the air without any special precautions being necessary.
Dispenser cathodes comprising such a presintered mass of alkaline-earth oxide split off very little gas only during their preparation in the tube, since disintegration of the carbonates is not necessary and the oxide mass has been well predegassed due to the treatment at high temperature.
In order that the invention may be readily carried into effect, it will now be described with reference to the accompanying drawing showing, by way of example, two cathodes each comprising a supply according to the invention.
ln Fig. l, reference numeral 1 indicates a molybdenum body, in which 2 is the space intended for a filament and 3 is a cavity containing a supply of alkaline-earth oxide 4. Above the cavity there is shown a porous tungsten body 5 which, after the supply 4 has been provided, is secured by butt welding to a sharp edge 6. The supply 4 may be formed by either of the two following methods. The first method is the following: a pressed pastille of barium strontium carbonate containing at least 25 at.% of strontium carbonate is heated in a platinum crucible in a vacuum oven at 1500 C. for 5 minutes. TheA pas tille is subsequently provided in the cavity 3. The second method is the following: a quantity of barium strontium carbonate is pressed into the cavity 3, whereafter the molybdenum body containing the supply is at first heated at 1000 C. for l hour and subsequently at a temperature of 1500 C. for 5 minutes. The durability of the pastille obtained by the rst method as well as that of the open space with the supply provided therein is at least hours in air.
In Fig. 2, reference number 7 indicates a cylindrical molybdenum body having a at flange 8 which is engaged by a porous tungsten body 9, a at ange 10 of a molybdenum cylinder 11 engaging the' other side of the tungsten body. The cavity between the body 9 and the cylindrical body 7 contains a supply of alkaline-earth oxide, indicated by 12, which is obtained by precipitation in a compact form. The precipitation is followed by heating in the same manner as in the case of the pressed carbonate shown in Fig. l. It is alternatively possible for a ymass of alkaline-earth carbonate of the desired shape to be heated in a vacuum oven and provided around the body 7. If sufficient allowance is made for contraction, it is possible to obtain a small cylinder of oxide of the correct size, or a plurality of sectors of a. cylinder, or it is possible to provide a plurality of profiled rods between the bodies 7 and 9. After the supply has been provided, the cathode is closed at 13, 14 and 15 by means of a circular welding seam.
What is claimed is:
l. In the method of manufacturing a dispenser cathode comprising a body of refractory metal having an internal cavity and at least one emissive surface portion, one wall portion surrounding said cavity being porous, the pores of said latter wall portion constituting the largest passageways connecting the cavity to said surface, the steps of forming a mixture of alkaline earth carbonates, sin- 25% of strontium carbonate.'` s
3. The method of claim 1 in which the sintered body is formed outside of the cavity.
4. The method of claim 1 in which the sintered body is formed within 'thez'avity but before" the"V cavityV is sealed.
References Cited in the ie of this patent UNITED STATES PATENTS Francis Feb. 23, 1937 Gustin Aug. 29, 1939 Gaidieset al. Oct. 10. 1939 Germeshausen Dec. 27, 1949 Lemmens et al Feb. 27, 1951 Levi Oct. 25, 1955
Claims (1)
1. IN THE METHOD OF MANUFACTURING A DISPENSER CATHODE COMPRISING A BODY OF REFRACTORY METAL HAVING AN INTERNAL CAVITY AND AT LEAST ONE EMISSIVE SURFACE PORTION, ONE WALL PORTION SURROUNDING SAID CAVITY BEING POROUS, THE PORES OF SAID LATTER WALL PORTION CONSTITUTING THE LARGEST PASSAGEWAYS CONNECTING THE CAVITY TO SAID SURFACE, THE STEPS OF FORMING A MIXTURE OF ALKALINE EARTH CARBONATES, SINTERING SAID MIXTURE IN A NON-REACTIVE ATMOSPHERE TO CONVERT THE SAME TO A COHERENT BODY OF ALKALINE EARTH OXIDES SUBSTANTIALLY IMPERVIOUS TO REACTIVE GASES, AND CLOSING SAID CAVITY AFTER PLACING THE SINTERED BODY THEREIN WHEREBY SAID CATHODE CAN BE ACTIVATED SUBSTANTIALLY WITHOUT THE RELEASE OF GASES.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| NL319758X | 1953-02-26 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| US2867742A true US2867742A (en) | 1959-01-06 |
Family
ID=19783943
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| US411222A Expired - Lifetime US2867742A (en) | 1953-02-26 | 1954-02-18 | Dispenser cathode |
Country Status (6)
| Country | Link |
|---|---|
| US (1) | US2867742A (en) |
| BE (1) | BE526781A (en) |
| CH (1) | CH319758A (en) |
| DE (1) | DE1028697B (en) |
| FR (1) | FR1093864A (en) |
| GB (1) | GB739645A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2965793A (en) * | 1959-05-12 | 1960-12-20 | Westinghouse Electric Corp | Electron device |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE1253818B (en) * | 1963-05-08 | 1967-11-09 | Hitachi Ltd | Gas discharge tubes |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2071973A (en) * | 1934-10-12 | 1937-02-23 | Gen Electric | Electric gaseous discharge device |
| US2171238A (en) * | 1937-09-02 | 1939-08-29 | Westinghouse Electric & Mfg Co | Discharge device and electrode |
| US2175345A (en) * | 1935-07-12 | 1939-10-10 | Gen Electric | Electric gaseous discharge device |
| US2492142A (en) * | 1945-10-17 | 1949-12-27 | Kenneth J Germeshausen | Electric system embodying coldcathode gaseous discharge device |
| US2543728A (en) * | 1947-11-26 | 1951-02-27 | Hartford Nat Bank & Trust Co | Incandescible cathode |
| US2721372A (en) * | 1951-06-30 | 1955-10-25 | Philips Corp | Incandescible cathodes |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE674258C (en) * | 1934-01-27 | 1939-04-11 | Telefunken Gmbh | Indirectly heated glow cathode for cathode ray tubes and process for their production |
| DE669029C (en) * | 1934-06-29 | 1938-12-15 | Siemens Schuckertwerke Akt Ges | Self-heating cathode |
-
0
- BE BE526781D patent/BE526781A/xx unknown
-
1954
- 1954-02-18 US US411222A patent/US2867742A/en not_active Expired - Lifetime
- 1954-02-23 GB GB5296/54A patent/GB739645A/en not_active Expired
- 1954-02-24 DE DEN8535A patent/DE1028697B/en active Pending
- 1954-02-24 CH CH319758D patent/CH319758A/en unknown
- 1954-02-24 FR FR1093864D patent/FR1093864A/en not_active Expired
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2071973A (en) * | 1934-10-12 | 1937-02-23 | Gen Electric | Electric gaseous discharge device |
| US2175345A (en) * | 1935-07-12 | 1939-10-10 | Gen Electric | Electric gaseous discharge device |
| US2171238A (en) * | 1937-09-02 | 1939-08-29 | Westinghouse Electric & Mfg Co | Discharge device and electrode |
| US2492142A (en) * | 1945-10-17 | 1949-12-27 | Kenneth J Germeshausen | Electric system embodying coldcathode gaseous discharge device |
| US2543728A (en) * | 1947-11-26 | 1951-02-27 | Hartford Nat Bank & Trust Co | Incandescible cathode |
| US2721372A (en) * | 1951-06-30 | 1955-10-25 | Philips Corp | Incandescible cathodes |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2965793A (en) * | 1959-05-12 | 1960-12-20 | Westinghouse Electric Corp | Electron device |
Also Published As
| Publication number | Publication date |
|---|---|
| BE526781A (en) | |
| GB739645A (en) | 1955-11-02 |
| DE1028697B (en) | 1958-04-24 |
| FR1093864A (en) | 1955-05-10 |
| CH319758A (en) | 1957-02-28 |
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