2007 Fiscal Year Final Research Report Summary
Study on Weakly Relativistic Slow-Wave Devices up to Millimeter Wave Region Based on Surface Wave Excitation with Anomalous Doppler Etffect
| Project/Area Number |
17340171
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Plasma science
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| Research Institution | Niigata University |
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Principal Investigator |
OGURA Kazuo Niigata University, Institute of Science and Technology, Professor (40214093)
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| Co-Investigator(Kenkyū-buntansha) |
SUGAWARA Akira Niigata University, Institute of Science and Technology, Associate Professor (00270934)
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| Project Period (FY) |
2005 – 2007
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| Keywords | anomalous Doppler effect / surface wave / oversize / mode control / cold cathode / weakly relativistic region / slow cyclotron interaction / Cherenkov interaction |
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| Research Abstract |
This research project aims at exciting the surface wave of oversized slow-wave structure by weakly relativistic electron beams. In a weakly relativistic region, one of critical problems is the electron beam generation with large currents. With a disk type cold cathode, uniformly distributed annular beams are able to be generated in the weak relativistic region. For the beam recovery port, further examination will be required. By improving the electron beam and the electromagnetic properties of oversized waveguide, radiation powers increase up to about 500kW at the 20GHz band and about 200kW at the 40GHz band. It is demonstrated that axisymmetric and nonaxisymmetric operation modes can be controlled.
With rectangular corrugations of slow-wave structure, a flat upper cutoff is realized. Cherenkov and slow cyclotron interactions are synchronized in a relatively low energy region. And the surface wave can be excited based on the anomalous Doppler effect. The surface wave excitation and surface mode control are demonstrated in the relatively low energy region with the low magnetic field.
In order to evaluate the electromagnetic properties of oversized waveguide experimentally, a measurement system using a vector network analyzer is prepared. The dispersion characteristics are estimated, by measuring resonant modes of 20 GHz-band slow-wave structure. Further examinations of millimeter wave excitation antenna will be required.
In numerical analysis, the problem of numerical divergence is resolved and beam interactions with the surface wave in oversized waveguide become to be analyzed including three-dimensional beam perturbations. The normal modes and their interactions with electron beams are investigated, comparing with the experimental results.
The surface wave excitation by the anomalous Doppler effect in the weakly relativistic region is an important issue from the viewpoint of plasma waves, waves in flowing plasmas and their applications.
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Research Products
(49 results)
