Design and development of an efficient high-power X-band relativistic magnetron
Abstract
This proposal is in response to recent interest in defense circles in high power microwave (HPM) sources in the frequency ranges ofX-band (8 # 12 GHz) and above. Most HPM activity so far has been in the L- and S-bands and ultra-wideband, reaching peak power of hundreds of MW to GW#s and pulse duration of 10^-9 # 10^-6 s. Research in HPM has been conducted in many universities and national laboratories (USA, UK, France, Germany, Russia, Japan, China, India, and Israel, among others) resulting in great progress and understanding of the processes that accompany the generation of such HPM pulses [1]. Very little work has been invested in the high frequency regions of interest here. Many of the HPM sources developed suffer from pulse shortening, that is, the plasma explosive emission electron source expands inside the slow wave structure (SWS), changing its characteristics so that the resulting HPM pulse terminates earlier than the duration of the supplied high voltage pulse. During our previous ONRG project (GRANT No. 13204703) we proposed, studied, and demonstrated a novel concept, the split-cathode, which alleviates pulse-shortening significantly in a relativistic magnetron [2]. In the split-cathode the explosive emitter operates outside the electromagnetic interaction volume and if it is sufficiently upstream from it, no pulse shortening appears for as long as the voltage is on. A relativistic magnetron (RM) is a comparatively simple device but to design it to operate at higher frequencies its dimensions need to be reduced and the magnetic field increased. Such a device operating at a 3.3 cm wavelength was developed by Kovalev, Fuks and others (KF) in the Soviet Union [3] in an axial diffraction output configuration. The dimensions of this device were unknown until recently and our attempts to use conventional magnetron design rules [4] were not very successful at high voltage. The KF magnetron turns out to be a very good starting point which weverified by PIC simulations. The optimization theory developed by Fuks in his PhD thesis is not complete but it shows a way to increase the operating frequency in the X-band. The experimental results in Ref. [3] show the development of pulse shortening as one would expect. To obtain long HPM pulses with no pulse shortening at the required very small cathode-anode distances the split-cathode is advantageous. Our goal is to develop X-band magnetrons fed by a split-cathode following the pioneering work of Kovalev and Fuks.REFERENCES[1] J. Benford, J. Swegle, and E. Schamiloglu, High Power Microwaves, 3rd ed. (CRC Press, Boca Raton, FL, 2015).[2] Ya. E. Krasik et al., J. Appl. Phys. 131, 023301 (2022)[3] N.F. Kovalev et al., Sov. Tech. Phys. Lett. 3, 430 (1977)[4] G.B. Collins, Microwave Magnetrons, McGraw Hill Book Company, New York, 1948
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Nov 09, 2024
- Source ID
- N629092412093
Entities
People
- Yakov Krasik
Organizations
- Office of Naval Research
- United States Navy