This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2020-201039, filed on Dec. 3, 2020; the entire contents of which are incorporated herein by reference.
Embodiments described herein relate generally to an electron-emitting electrode and a magnetron.
For example, an electron-emitting electrode such as a thermionic element or the like is provided in a magnetron. It is desirable to increase the efficiency of the electron-emitting electrode.
According to one embodiment, an electron-emitting electrode includes a first member, a first diamond member, and a second diamond member. A surface of the first member includes a first region and a second region. The first diamond member is provided at the first region. The first diamond member includes a first element. The first element includes at least one selected from the group consisting of nitrogen, phosphorus, arsenic, antimony, and bismuth. The second diamond member is provided at the second region. The second diamond member includes a second element. The second element including at least one selected from the group consisting of boron, aluminum, gallium, and indium.
According to one embodiment, a magnetron includes the electron-emitting electrode described above, and an opposite electrode facing the electron-emitting electrode. A gap is provided between the electron-emitting electrode and the opposite electrode.
Various embodiments are described below with reference to the accompanying drawings.
The drawings are schematic and conceptual; and the relationships between the thickness and width of portions, the proportions of sizes among portions, etc., are not necessarily the same as the actual values. The dimensions and proportions may be illustrated differently among drawings, even for identical portions.
In the specification and drawings, components similar to those described previously or illustrated in an antecedent drawing are marked with like reference numerals, and a detailed description is omitted as appropriate.
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The first diamond member 21 is located at the first region 11. The first diamond member 21 includes diamond and a first element. The first element includes at least one selected from the group consisting of nitrogen, phosphorus, arsenic, antimony, and bismuth. For example, the first diamond member 21 is of an n-type.
The second diamond member 22 is located at the second region 12. The second diamond member 22 includes diamond and a second element. The second element includes at least one selected from the group consisting of boron, aluminum, gallium, and indium. For example, the second diamond member 22 is of a p-type.
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For example, thermions are emitted from the first diamond member 21. For example, primary electrons are emitted from the first diamond member 21. For example, secondary electrons are emitted from the second diamond member 22. For example, the electron-emitting electrode 110 is applicable as the cathode of a magnetron, etc. In such a case, for example, the electrons that are emitted from the first diamond member 21 are incident on the second diamond member 22. Thereby, secondary electrons are emitted from the second diamond member 22.
For example, conductive diamond has negative electron affinity. The conduction band level of such a material is higher than the vacuum level. Electrons are easily emitted from such a material. Electrons are easily emitted by the cathode that includes conductive diamond even when the temperature of the first member 10 is low. For example, n-type diamond is used as the conductive diamond that emits the primary electrons.
For example, when the electron-emitting electrode 110 is used as the cathode of a magnetron, etc., a portion of the thermions that are emitted has cyclotron motion and strikes the cathode due to a reverse impact phenomenon. The cathode can efficiently emit secondary electrons by including a material that has a high emission efficiency of secondary electrons. Conductive diamond can be used as the material that emits secondary electrons. For example, p-type diamond is used as the material that emits secondary electrons.
According to the embodiment, the electron emission of the second diamond member 22 can be utilized in addition to the emission of the electrons from the first diamond member 21. A highly efficient electron emission is obtained thereby. According to the embodiment, an electron-emitting electrode is provided in which the efficiency can be increased.
For example, a reference example may be considered in which a metal oxide or the like is provided instead of p-type diamond. The emission efficiency of secondary electrons of the reference example is low. According to the embodiment, secondary electrons can be emitted with high efficiency by providing the p-type second diamond member 22.
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The surface of one of the first diamond member 21 or the second diamond member 22 may include a surface asperity. For example, the surface asperity of these members may be caused by the diamond crystal grains.
For example, the second diamond member 22 may include an uneven configuration (including a protruding shape) having a depth that is not more than 50 μm. Secondary electrons are easily emitted by the uneven configuration.
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According to the embodiment, the second height H2 is not less than 1.5 times and not more than 10 times the first height H1. For example, the second height H2 is not more than 5 μm. Thereby, the emission of the electrons from the second diamond member 22 is easier.
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According to the embodiment, it is favorable for the ratio of the surface area of the second region 12 to the surface area of the first region 11 to be not more than 0.1. For example, the surface area of the first region 11 is not less than 10 times the surface area of the second region 12. For example, the surface area of the first diamond member 21 is not less than 10 times the surface area of the second diamond member 22. Thereby, a high amount of primary electrons is emitted from the first diamond member 21. A high amount of primary electrons increases the amount of the electrons incident on the second diamond member 22. As a result, a high amount of secondary electrons is emitted from the second diamond member 22.
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According to the embodiment, the surface 10F of the first member 10 may include multiple first regions 11. For example, multiple first diamond members 21 may be provided. The second region 12 may be located between one of the multiple first regions 11 and another one of the multiple first regions 11. For example, one of the multiple first diamond members 21 is located at the one of the multiple first regions 11. Another one of the multiple first diamond members 21 is located at the other one of the multiple first regions 11. For example, the ratio of the surface area of the second region 12 to the sum of the surface areas of the multiple first regions 11 is not more than 0.1. For example, the ratio of the surface area of the second diamond member 22 to the sum of the surface areas of the multiple first diamond members 21 is not more than 0.1.
According to the embodiment, the surface 10F of the first member 10 may include multiple second regions 12. For example, multiple second diamond members 22 may be provided. For example, the one of the multiple first regions 11 may be between one of the multiple second regions 12 and another one of the multiple second regions 12. One of the multiple second diamond members 22 is located at the one of the multiple second regions 12. Another one of the multiple second diamond members 22 is located at the other one of the multiple second regions 12. For example, the ratio of the sum of the surface areas of the multiple second regions 12 to the sum of the surface areas of the multiple first regions 11 is not more than 0.1. For example, the ratio of the sum of the surface areas of the multiple second diamond members 22 to the sum of the surface areas of the multiple first diamond members 21 is not more than 0.1.
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For example, a homogeneous diamond member is easily obtained by the diamond member including a polycrystal. For example, an efficient electron emission is stably and easily obtained by the diamond member including a hydrogen region.
These drawings illustrate the first polycrystal 21c or the second polycrystal 22c.
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For example, the emission of the secondary electrons from the second diamond member 22 is more efficiently performed by increasing the proportion of the (111) plane.
For example, the second polycrystal 22c includes the (111) plane. The second polycrystal 22c does not include the (100) plane. Or, the proportion of the (100) plane in the second polycrystal 22c is less than the proportion of the (111) plane in the second polycrystal 22c. A highly efficient electron emission is easily obtained thereby.
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The second member 15 is conductive. The second member 15 includes, for example, tungsten. The second member 15 may include, for example, tungsten and at least one selected from the group consisting of thorium oxide and cerium oxide. The tungsten concentration in the second member 15 is, for example, not less than 90%. The melting points of these materials are high. For example, any material that has a melting point that is not less than 1200° C. may be used as the second member 15. In the example, the second member 15 is spiral-shaped.
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For example, a current is supplied between the second end portion 15e and the second other-end portion 15f via the first electrode terminal T1 and the second electrode terminal T2. The second member 15 is heated by the current. The temperature of the first member 10 is increased by the heated second member 15. Electrons are emitted from the first and second diamond members 21 and 22 as the temperature of the first member 10 increases. For example, primary electrons are emitted from the first diamond member 21. For example, secondary electrons are emitted from the second diamond member 22.
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A first magnet 51 and a second magnet 52 are provided as shown in
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According to the embodiment, a magnetron can be provided in which the efficiency can be increased.
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According to the embodiment, thermions can be obtained at a low temperature. Refractory metal members at the periphery of the hot cathode can be replaced with inexpensive metals. For example, the cooling structures of fins, etc., can be simplified.
According to the embodiment, an electron-emitting electrode and a magnetron can be provided in which the efficiency can be increased.
In the specification, “a state of electrically connected” includes a state in which multiple conductors physically contact and a current flows between the multiple conductors. “a state of electrically connected” includes a state in which another conductor is inserted between the multiple conductors and a current flows between the multiple conductors.
Hereinabove, exemplary embodiments of the invention are described with reference to specific examples. However, the embodiments of the invention are not limited to these specific examples. For example, one skilled in the art may similarly practice the invention by appropriately selecting specific configurations of components included in electron-emitting electrodes such as members, diamond members, terminals, etc., from known art. Such practice is included in the scope of the invention to the extent that similar effects thereto are obtained.
Further, any two or more components of the specific examples may be combined within the extent of technical feasibility and are included in the scope of the invention to the extent that the purport of the invention is included.
Moreover, all electron-emitting electrodes, and magnetrons practicable by an appropriate design modification by one skilled in the art based on the electron-emitting electrodes, and the magnetrons described above as embodiments of the invention also are within the scope of the invention to the extent that the purport of the invention is included.
Various other variations and modifications can be conceived by those skilled in the art within the spirit of the invention, and it is understood that such variations and modifications are also encompassed within the scope of the invention.
While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel embodiments described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the embodiments described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the invention.
Number | Date | Country | Kind |
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2020-201039 | Dec 2020 | JP | national |