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Analysis and experimental results for an extraction cavity for the split-cavity oscillator

Conference ·
OSTI ID:10174768

The kinetic energy in a split-cavity oscillator`s (SCO`s) modulated beam must be converted into microwave energy in a waveguide. ne efficiency of this conversion process is a major factor in the overall efficiency of this source. The low-impedance beam used with the SCO typically a few kiloamperes at 140 kV -- with the accompanying space-charge effects and beam loading of the output gap, differentiates the extractor design for an SCO from that of more conventional beam-modulation tubes. This paper will discuss an analytical and experimental effort to design an extractor cavity for a 1 GHz SCO that has optimum Q and shunt impedance. Our approach was to build a rectangular extraction cavity of known, variable Q. This serves the dual purpose of enabling us to search the parameter space for an optimum coupler and to evaluate the modulation characteristics of the beam, since the power output at optimum Q is related to the beam`s energy and modulation characteristics. We will discuss a chain-parameter matrix model of the cavity, beam loading effects, and experimental results for power output as a function of extraction cavity parameters.

Research Organization:
Sandia National Labs., Albuquerque, NM (United States)
Sponsoring Organization:
USDOE, Washington, DC (United States)
DOE Contract Number:
AC04-76DP00789
OSTI ID:
10174768
Report Number(s):
SAND--92-0876C; CONF-9208127--1; ON: DE92040262
Country of Publication:
United States
Language:
English