| 摘要 |
PROBLEM TO BE SOLVED: To prevent a work function change (decrease in emission current), discharge break down of an emitter, and the like, accompanying an increase in gate current, by adopting two electron emission sources, an electron emission source to be used at a lower voltage than a positive electrode voltage and a secondary emission source with a secondary-emission ratio larger than a specific value under the magnetron operating conditions. SOLUTION: Two kinds of electron emission sources are adopted, an electron emission source, such as a triode-structured field emitter array 32 integrated by micro machining techniques, to be used at a lower voltage than a positive electrode voltage, and a secondary emission source 35. The emitter array 32 supplies electrons to a magnetron until it starts operation, and the secondary emission source 35 with a secondary-emission ratio of its negative electrode surface larger than one in an interacting space, supplies electrons while the magnetron operates. Because an insulating layer 34 is formed on a gate electrode 33 of the emitter array 32 and the secondary-emission film 35 is formed thereon, when an output is increased, most of reverse-impact electrons collide with the secondary-emission film 35, and breakage, etc., of the emitter array 32 can be prevented.
|
