Numerical simulation of backward wave oscillators having nonuniform amplitude slow wave structures

Book · Sat Dec 31 04:00:00 EST 1994

OSTI ID:51773

Lemke, R W ^[1]; Moreland, L D; Schamiloglu, E ^[2]; Korovin, S D; Pegel, I V; Roitman, A M ^[3]

---

1. Sandia National Labs., Albuquerque, NM (United States)
2. Univ. of New Mexico, Albuquerque, NM (United States). Dept. of Electrical and Computer Engineering
3. Russian Academy of Sciences, Tomsk (Russian Federation). Inst. of High Current Electronics

Experiments involving backward wave oscillators having nonuniform amplitude slow wave structures (NBWOs) operating in the x-band frequency range have produced 500 MW of rf power with 20% efficiency. To elucidate the processes occurring in the NBWO, and to ascertain the possible advantage of using a nonuniform amplitude sow wave structure over one that is uniform, the authors have performed a simulation study involving several different tubes, nonuniform and uniform, using the 2.5D electromagnetic particle-in-cell code TWOQUICK. The simulations model experiments performed on the SINUS-6 electron beam accelerator at the University of New Mexico. Results of the simulation study are presented. They show that the slow phase velocity surface wave that interacts with the electron beam coexists with an ordinary waveguide mode, which forms a standing wave in both nonuniform and uniform BWOs. Analysis of BWOs using a single particle phase model that accounts for both fast and slow TM waves shows that it may be possible to increase the output power of these tubes in general by choosing the length of the slow wave structure to simultaneously optimize the coupling of the beam to the slow wave, while forcing a transit time interaction between the standing wave and the electron beam, which pumps beam energy directly into the ordinary waveguide mode. The authors discuss the possible advantages of using a NBWO to accomplish this. In addition, comparisons with SINUS-6 experiments are made.

• Research Organization: Sandia National Laboratory
• DOE Contract Number: AC04-94AL85000
• OSTI ID: 51773
• Report Number(s): CONF-940604--; ISBN 0-7803-2006-9
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
BACKWARD WAVE TUBES
COMPARATIVE EVALUATIONS
COMPUTERIZED SIMULATION
DESIGN
PERFORMANCE
T CODES
THEORETICAL DATA