Improvement of the Output Characteristics of a Relativistic Magnetron using a Small Diameter Cathode Surrounded by a Transparent Cathode
Abstract
Conventional magnetrons in which cathodes with thermionic and/or secondary electron emission are used operate poorly when the ratio of the anode-to-cathode radius is large, R sub a /R sub c > 2~2.5 , because of unfavorable starting conditions and strong mismatch of the synchronous particle-field interaction. The field of the operating mode, which decreases exponentially from the resonant system cavities to the cathode, becomes too weak on the electron flow rotating over the cathode to capture electrons to the anode. On other hand, the azimuthal drift velocity of electrons is inversely proportional to radius, V sub e ~r -1, whereas the phase velocity of the wave has the opposite tendency, V sub ph ~r, and the electron space charge field promotes synchronism V sub e approximately equal V sub ph in the total interaction space when the gap between electrodes is narrow. However, for a magnetron with a small R sub c mismatch of the synchronism becomes so large that the appearance of additional electron drift leads to strong deformation of electron spokes, and even to the disappearance of the anode current I sub a.
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 01, 2006
- Accession Number
- ADP022695
Entities
People
- Edl Schamiloglu
- H. Bosman
- L. Bowers
- M. Fuks
- P. Mardhal
- S. Prasad
- T. Fleming
Organizations
- Air Force Research Laboratory