Session UP1 - Poster Session.
POSTER session, Friday morning, November 19
Grand III, The Westin Seattle
Seventh-harmonic gyroharmonic co-generation [Wang, Hirshfield and Ganguly, Phys. Rev. Lett. 77, 3819 (1996)] has been suggested as a mechanism that could be the basis for a multi-MW cm-wavelength rf sources for use in research on high-gradient accelerators. This mechanism is based on the coincidental fact that, for a uniform cylindrical waveguide, a 7^th-harmonic TE_72 wave has nearly the same group velocity as a fundamental-frequency TE_11 wave. An apparatus to demonstrate 7^th-harmonic co-generation has been built and tested, in which a 250 kV, 23 A laminar beam has up to 10 MW of 2.856 rf power added to it in the TE_11mode of a cylindrical waveguide terminated in a matched load, whence the spectrum of generated harmonic power is analyzed. Conditions are found in which 7^th-harmonic 20 GHz output dominates the harmonic spectrum. Preliminary designs are presented of a two-cavity system to exploit this novel means of efficient up-conversion for generation of high-power at 20 GHz (or at 80 GHz, were the rf driver to be at 11.424 GHz).