TITLE:
Integrated Design of a Compact and Lightweight S-Band Traveling-Wave Tube Amplifier for a New Class of Microwave Power Module
AUTHORS:
Heather Song, Leslie Tekamp, Frank Francisco, Ming-Chieh Lin, Peter H. Stoltz, David Smith, Gil Wong Choi, Jin Joo Choi
KEYWORDS:
TWT; MPM; Compact; Lightweight; Feedback Current Loop; Multi-Stage Collector
JOURNAL NAME:
Journal of Electromagnetic Analysis and Applications,
Vol.5 No.3,
March
28,
2013
ABSTRACT:
A new class of compact and lightweight S-band 1 kW traveling-wave tube (TWT) is
being developed for a microwave power module (MPM) that will be used for phased
antenna array radar applications. The proposed S-band MPM provides a tenfold
peak power increase compared to state-of-the-art S-band MPMs. In this paper,
the design of the vacuum power booster TWT part of the MPM is presented. The
compact and lightweight S-band TWT is driven by a 6 kV, 0.9 A electron beam. The amplifier is predicted by
large-signal simulations to generate over 1 kW at S-band with 25 dB saturated
gain and over 40% efficiency. The stability from unwanted oscillations has been
investigated. To suppress the oscillations, the helix circuit has been coated
with carbon composite material. The coaxial input and output antennas have been
fabricated. For efficiency enhancement, a multi-stage depressed collector (MDC)
has been designed using a 3D particle-in-cell (PIC) simulator, VORPAL. The
collector design makes use of a current loop based on a feedback mechanism for
effective design process. The integrated designs of a helix circuit, an
electron gun, a periodic permanent magnet (PPM), antennas, and a collector are
presented.