1993 Fiscal Year Final Research Report Summary
Development of a Highi-Frequency, High-Power Virtual Cathode
| Project/Area Number |
04650248
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
電力工学
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| Research Institution | Himeji Institute of Technology |
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Principal Investigator |
NOBUHARA Sadao Himeji Institute of Techonology Dept.of Engineering, Professor, 工学部, 教授 (80047571)
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| Co-Investigator(Kenkyū-buntansha) |
YATSUZUKA Mitsuyasu Himeji Institute of Techonology Dept.of Engineering, Associate Professor, 工学部, 助教授 (50047601)
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| Project Period (FY) |
1992 – 1993
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| Keywords | Virtual Cathode Oscillator / Vircator / High-Power Microwave / Microwave / Relativistic Electron Beam |
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| Research Abstract |
High-power microwave generation in an axially-extracted virtual cathode oscillator has been studied experimentally with an annular cathode (radius : 1.0 - 1.5 cm and thickness : 0.1 cm) and an aluminum-foil anode of 15 mum in thick. The Electron beam emitted from the annular cathode passed through the anode foil and reached a circular waveguide (radius 2.25 cm and 2 m long), while the microwave radiation propagated along the circular waveguide to a matiched termination.
The microwave emission of 1.2 GW at frequencies in the range of 15 GHz is observed in the presence of annular electron beam operated at a 300 kV and 20 kA.The microwave rises in 10 nsec and the pulse duratin of 15 nsec is much shorter than the beam pulse width of 80 nsec. The electron beam current on the diode region is well characterized by the electron space-change-limited current in bipolar flow midified for gap closure due to expanding anode and cathode plasmas. The beam current is well below the critical current defined for diode pinching. A sudde increase of the diode impedance, indicating a manifestation of electron beam pinching, was observed just before the microwave emission.
Essential feature of such a pinching effect for the microwave generation is confirmed by the absence of emission when the pinch of electron beam is suppressed by the application of the axial magnetic field.
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