Open AccessEmittance Effects on Gain in $W$ -Band TWTs
Author(s) -
Bruce E. Carlsten,
Kimberley E. Nichols,
Dmitry Yu. Shchegolkov,
Evgenya I. Simakov
Publication year - 2016
Publication title -
ieee transactions on electron devices
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.828
H-Index - 186
eISSN - 1557-9646
pISSN - 0018-9383
DOI - 10.1109/ted.2016.2612583
Subject(s) - components, circuits, devices and systems , engineered materials, dielectrics and plasmas
We consider the main effects of beam emittance on W-band traveling-wave tube (TWT) performance and gain. Specifically, we consider a representative dielectric TWT structure with ~5 dB/cm of gain driven by a 5-A, 20-keV, sheet electron beam that is focused by a wiggler magnetic field. The normalized beam transverse emittance must be about 1 μm or lower to ensure that both the transport is stable and the gain is not degraded by the effective energy spread arising from the emittance. This emittance limit scales roughly inversely with frequency.