3D PIC simulation study of a relativistic, rising sun magnetron
The magnetron oscillator can be a highly efficient device for generating microwaves. When operated at low voltage (V < 100 kV) efficiencies greater than 50% can be achieved. At relativistic voltages (V{approximately}500 kV), however, the peak efficiency is generally much less than 30%. Results of a recent numerical study of the A6 magnetron suggest that the low efficiencies realized in previous relativistic magnetron experiments were due more to using an inappropriate tube configuration than to relativistic effects. In particular, it was suggested that efficient high power operation at relativistic voltages would require a significant increase in tube dimensions relative to the free-space wavelength of the desired mode. To test this hypothesis, the authors have performed a numerical study of a 14 cavity magnetron oscillator using 3D particle-in-cell (PIC) simulation. They investigated the performance of this tube in the range of operating voltages 300 < V < 650 kV, and corresponding applied magnetic field in the range 1.3 < B{sub z} < 1.95 kG. In the numerical experiments this tube yielded maximum power and efficiency at the high end of the voltage range; approximately 4 GW power at 25% efficiency at 600 kV. This efficiency is similar to that achieved in earlier work with rising suns operated at low voltage. Overall the results suggest that this efficiency is not limited by effects associated with high voltage, but by inherent shortcomings of a rising sun configuration (e.g., contamination by the zero-harmonic of the {pi}-mode). In addition, they find that the rising sun configuration can shift mode competition from the n=6 to the n=3 or n=4 modes depending on the ratio of cavity depths.
- Research Organization:
- Sandia National Labs., Albuquerque, NM (US)
- Sponsoring Organization:
- US Department of the Air Force; USDOE
- DOE Contract Number:
- AC04-94AL85000
- OSTI ID:
- 20067661
- Resource Relation:
- Conference: 1999 IEEE International Conference on Plasma Science, Monterey, CA (US), 06/20/1999--06/24/1999; Other Information: PBD: 1999; Related Information: In: The 26th IEEE international conference on plasma science, 342 pages.
- Country of Publication:
- United States
- Language:
- English
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Investigation of Rising-Sun Magnetrons Operated at Relativistic Voltages Using Three Dimensional Particle-in-Cell Simulations
Investigation of rising-sun magnetrons operated at relativistic voltages using three-dimensional particle-in-cell simulation