US2581460A - Electron multiplier - Google Patents
Electron multiplier Download PDFInfo
- Publication number
- US2581460A US2581460A US767018A US76701847A US2581460A US 2581460 A US2581460 A US 2581460A US 767018 A US767018 A US 767018A US 76701847 A US76701847 A US 76701847A US 2581460 A US2581460 A US 2581460A
- Authority
- US
- United States
- Prior art keywords
- emissive
- electrode
- electron
- borate
- envelope
- 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
- 239000000463 material Substances 0.000 claims description 7
- 229910052784 alkaline earth metal Inorganic materials 0.000 claims description 5
- 150000001342 alkaline earth metals Chemical class 0.000 claims description 3
- 238000000151 deposition Methods 0.000 description 9
- BTBUEUYNUDRHOZ-UHFFFAOYSA-N Borate Chemical compound [O-]B([O-])[O-] BTBUEUYNUDRHOZ-UHFFFAOYSA-N 0.000 description 8
- 239000011149 active material Substances 0.000 description 8
- 230000008016 vaporization Effects 0.000 description 7
- 239000003513 alkali Substances 0.000 description 5
- 230000008021 deposition Effects 0.000 description 5
- 239000002775 capsule Substances 0.000 description 3
- 238000010438 heat treatment Methods 0.000 description 3
- DSAJWYNOEDNPEQ-UHFFFAOYSA-N barium atom Chemical group [Ba] DSAJWYNOEDNPEQ-UHFFFAOYSA-N 0.000 description 2
- 238000000576 coating method Methods 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 230000002159 abnormal effect Effects 0.000 description 1
- 238000001994 activation Methods 0.000 description 1
- 229910052788 barium Inorganic materials 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 150000001642 boronic acid derivatives Chemical class 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000007598 dipping method Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 238000005507 spraying Methods 0.000 description 1
Images
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J43/00—Secondary-emission tubes; Electron-multiplier tubes
- H01J43/04—Electron multipliers
- H01J43/28—Vessels, e.g. wall of the tube; Windows; Screens; Suppressing undesired discharges or currents
Definitions
- This invention relates to electron discharge devices of the electron multiplier type. It is primarily concerned with such devices having a thermionic primary electron source, but is generally applicable where secondary emissive electrodes tend to lose their emissive power.
- an electron multiplier employing a hot oxide-coated cathode as the source of primary electrons tends to have a short life.
- Various explanations of this short life have been put forward, but the most generally accepted one is that the atoms, for example barium atoms in the case of a, barium xide coating, are evaporated from the oxide-coated cathode and are deposited on the secondary-emissive surface or surfaces.
- a contaminating layer is gradually built up on the sensitive surface and the net secondary emission ratio falls to a value characteristic of the con# taminating material.
- the deposition may be effected continuously under normal operating conditions, for example, from an adjacent carrier of the active material which becomes heated under such operating conditions, or the deposition can be effected at desired intervals, for example by applying abnormal voltages or currents to some r all of theelectrodes.
- the carrier may incorporate a heater so that its temperature can be more readily controlled.
- the carrier may be constituted by a grid like anode disposed in iront of the secondary electron emissive surface, the temperature of the anode being determined solely by electron bombardment and conduction from neighbouring electrodes or primarily by an individual heater or heating current.
- the carrier may be constituted by a small container for the active material, heating means being provided for the container.
- active material a substance with an appreciable vapour pressure at a temperature of. say 300 C.
- this substance is deposited by spraying, dipping or some other suitable coating method upon a grid-shaped anode immediately in front of the secondary emission electrode.
- this gridshaped anode is raised to a high temperature so that some of the active material evaporates off and deposits on the secondary emission electrode to form the initial layer.
- This tube is then sealed off from the exhaust pump, and may or may not be submitted to an activation process.
- the operating conditions are such that active material is continuously evaporated off from the anode on to the secondary cathode. Th-us, throughout the life of the tube the sensitive surface is always being renewed and the arrival of contaminating atoms from the primary cathode becomes of minor importance.
- FIG. 1 illustrate structures incorporating the invention wherein the active material is stored in a small container adjacent to the secondary emissive surfaces but out of the electron path.
- Each figure ' shows a section through the axis of the electrode structure which will be mounted in an evacuated envelope.
- C is a tubular indirectly heated cathode
- Gl a control grid
- G2 an accelerating grid
- A a collecting electrode or anode of grid formation
- SE secondary-electron emissive plates.
- Small'containers or capsules K are loaded with active material S for deposition on the emissive plates SE and carry a heater resistance R having suitable leading-in connections.
- the initial emissive layer upon the plates SE may be deposited after the assembly and evacuation of the device, this deposition being effected by passing a suitable current through the heater or heaters R.
- the emissive plates may be continuously or intermittently activated by suitably energising the heater to vapourise the stored material.
- Electron discharge device according to claim l 1 wherein said vaporizing means includes a capsule containing said borate positioned adjacent the secondary emissive surface of said electrode and a heating element for controlling the temperature of the capsule.
- Electron discharge device comprising a secondary electron-emissive electrode wherein the secondary emissive material of saidelectrode comprises a borate of a metal selected from the group including alkali and alkaline earth metals.
- Electron discharge device comprising an en- ⁇ velope, a secondary electron-emissive electrode within said envelope, a quantity of an alkali borate within said envelope spaced from said electrode and vaporizing means spaced from said electrode for depositing said alkali borateupon Y said electrode during operation of said device.
- Electron discharge device comprising an envelope, a secondary electron-emissive electrode within said envelope, a quantity of an alkaline earth borate within said envelope spaced from said electrode, and vaporizing means spaced from said electrode for depositing said alkaline earth borate upon said electrode during operation of said device.
- Electron discharge device comprising an envelope having therein a source 'of primary electrons, a secondary electron-emissive electrode located in the path of said primary electrons from said source and having a secondary emissive surface incident to said path, a given Yquantity of borate of a metal selected from the group including alkali and alkaline earth metals disposed outside of said path, and directive vaporizing means disposed outside the path of said incident electrons and including a vaporizing portion directed obliquely to said secondary emissive surface of said electrode for depositing said borate upon said surface during operation of the device.
- Electron discharge device comprising an envelope having therein a source of primary electrons, a secondary electron-emissive electrode located in the path of said primary electrons from said source and having a secondary emissive surface incident to said path, a given quantity of an active secondary emissive material within said envelope and adjacentsaid secondary electronemissive electrode, and directive vaporizing means disposed outside the path of said incident electrons and including a vaporizing portion directed obliquely to said secondary emissive surface of said electrode for depositing said active secondary emissive material upon said surface during operation of the device.
Landscapes
- Electron Sources, Ion Sources (AREA)
- Discharge Lamp (AREA)
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB260192X | 1939-02-03 |
Publications (1)
Publication Number | Publication Date |
---|---|
US2581460A true US2581460A (en) | 1952-01-08 |
Family
ID=10237073
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US767018A Expired - Lifetime US2581460A (en) | 1939-02-03 | 1947-08-07 | Electron multiplier |
Country Status (5)
Country | Link |
---|---|
US (1) | US2581460A (de) |
BE (1) | BE477661A (de) |
CH (1) | CH260192A (de) |
FR (1) | FR862597A (de) |
GB (1) | GB524658A (de) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3647286A (en) * | 1969-02-10 | 1972-03-07 | John H Delorme Jr | Reproduction apparatus using photovoltaic material |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2027025A (en) * | 1932-12-31 | 1936-01-07 | Rca Corp | Photo-electric device |
US2159774A (en) * | 1937-03-30 | 1939-05-23 | Philips Nv | Secondary electron emitter and method of making it |
US2228945A (en) * | 1937-03-30 | 1941-01-14 | Rca Corp | Electric discharge tube |
-
0
- BE BE477661D patent/BE477661A/xx unknown
-
1939
- 1939-02-03 GB GB3658/39A patent/GB524658A/en not_active Expired
- 1939-12-28 FR FR862597D patent/FR862597A/fr not_active Expired
-
1947
- 1947-04-09 CH CH260192D patent/CH260192A/de unknown
- 1947-08-07 US US767018A patent/US2581460A/en not_active Expired - Lifetime
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2027025A (en) * | 1932-12-31 | 1936-01-07 | Rca Corp | Photo-electric device |
US2159774A (en) * | 1937-03-30 | 1939-05-23 | Philips Nv | Secondary electron emitter and method of making it |
US2228945A (en) * | 1937-03-30 | 1941-01-14 | Rca Corp | Electric discharge tube |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3647286A (en) * | 1969-02-10 | 1972-03-07 | John H Delorme Jr | Reproduction apparatus using photovoltaic material |
Also Published As
Publication number | Publication date |
---|---|
GB524658A (en) | 1940-08-12 |
CH260192A (de) | 1949-02-28 |
FR862597A (fr) | 1941-03-10 |
BE477661A (de) |
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