Two and three dimensional simulation of diskloaded travellingwave output structures for highpower klystrons
Abstract
The authors have developed algorithms for designing diskloaded travellingwave output structures for Xband klystrons to be used in the SLAC NLC. They use either a four or five cell structure in a {pi}/2 mode. The disk radii are tapered to produce an approximately constant gradient. The matching calculation is not performed on the tapered structure, but rather on a coupler whose input and output cells are the same as the final cell of the tapered structure, and whose interior cells are the same as the penultimate cell in the tapered structure. 2D calculations using CONDOR model the waveguide as a radial transmission line of adjustable impedance. 3D calculations with MAFIA model the actual rectangular waveguide and coupling slot. A good match is obtained by adjusting the impedance of the final cell. In 3D, this requires varying both the radius of the cell and the width of the aperture. When the output cell with the best match is inserted in the tapered structure, they obtain excellent coldtest agreement between the 2D and 3D models. They use hottest simulations with CONDOR to design the structure with maximum efficiency and minimum surface fields. The azimuthal asymmetry due to the coupling iris can increasemore »
 Authors:
 Stanford Linear Accelerator Center, CA (United States)
 Publication Date:
 OSTI Identifier:
 63088
 Report Number(s):
 CONF940604
ISBN 0780320069; TRN: IM9527%%139
 DOE Contract Number:
 AC0376SF00515
 Resource Type:
 Book
 Resource Relation:
 Conference: 1994 Institute of Electrical and Electronic Engineers (IEEE) international conference on plasma science, Santa Fe, NM (United States), 68 Jun 1994; Other Information: PBD: 1994; Related Information: Is Part Of 1994 IEEE international conference on plasma science; PB: 252 p.
 Country of Publication:
 United States
 Language:
 English
 Subject:
 42 ENGINEERING NOT INCLUDED IN OTHER CATEGORIES; 43 PARTICLE ACCELERATORS; KLYSTRONS; WAVEGUIDES; LINEAR COLLIDERS; COMPUTERIZED SIMULATION; TWODIMENSIONAL CALCULATIONS; THREEDIMENSIONAL CALCULATIONS; PERFORMANCE; MESH GENERATION; THEORETICAL DATA
Citation Formats
Eppley, K.R.. Two and three dimensional simulation of diskloaded travellingwave output structures for highpower klystrons. United States: N. p., 1994.
Web.
Eppley, K.R.. Two and three dimensional simulation of diskloaded travellingwave output structures for highpower klystrons. United States.
Eppley, K.R.. 1994.
"Two and three dimensional simulation of diskloaded travellingwave output structures for highpower klystrons". United States.
doi:.
@article{osti_63088,
title = {Two and three dimensional simulation of diskloaded travellingwave output structures for highpower klystrons},
author = {Eppley, K.R.},
abstractNote = {The authors have developed algorithms for designing diskloaded travellingwave output structures for Xband klystrons to be used in the SLAC NLC. They use either a four or five cell structure in a {pi}/2 mode. The disk radii are tapered to produce an approximately constant gradient. The matching calculation is not performed on the tapered structure, but rather on a coupler whose input and output cells are the same as the final cell of the tapered structure, and whose interior cells are the same as the penultimate cell in the tapered structure. 2D calculations using CONDOR model the waveguide as a radial transmission line of adjustable impedance. 3D calculations with MAFIA model the actual rectangular waveguide and coupling slot. A good match is obtained by adjusting the impedance of the final cell. In 3D, this requires varying both the radius of the cell and the width of the aperture. When the output cell with the best match is inserted in the tapered structure, they obtain excellent coldtest agreement between the 2D and 3D models. They use hottest simulations with CONDOR to design the structure with maximum efficiency and minimum surface fields. The azimuthal asymmetry due to the coupling iris can increase the peak fields by 20 to 30 percent. They can reduce this problem by making the final cavity with a noncircular cross section. With proper dimensions, they can keep a good match while reducing the azimuthal asymmetry to 6 percent. They have designed circuits at 11.424 Ghz for several different perveances. At 440 kV, microperveance 1.2, they calculate 83 MW, 54 percent efficiency, peak surface field 76 MV/m. At microperveance 0.8, they calculate 60 MW, 58 percent efficiency, peak field 67 MV/m. At 465 kV, microperveance 0.6, they calculate 55 MW, 62 percent efficiency, peak field 63 MV/m.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = 1994,
month =
}

Simulation of travelingwave output structures for high power rf tubes
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