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DOI:10.18429/JACoW-IPAC2016-MOPMW039
Title TM01 Mode Launcher for Use in High Brightness Photoguns
Authors
  • A.D. Cahill
    UCLA, Los Angeles, California, USA
  • M. Dal Fornopresenter, V.A. Dolgashev
    SLAC, Menlo Park, California, USA
Abstract Photo rf guns are a source of electron beams for X-ray FELs such as LCLS and European XFEL. In existing photoguns power is coupled into the cavity by waveguides through the cell walls, like LCLS, or through coaxial coupling, at the European XFEL. We are considering feeding a gun using a circular waveguide with the TM01 mode. To do that we need a mode launcher, a matched device that couples the rectangular TE01 mode waveguide to a TM01 mode in a circular waveguide. Use of the mode launcher reduces complexity of the gun cavity and increases flexibility of positioning the input waveguide relative to the gun body. Mode launchers have been successfully used at SLAC and elsewhere for X-band high gradient tests. Because the existing mode launchers were not built for high brightness guns, they have a significant quadrupole field component. High brightness rf guns have tight requirements on output beam properties, and this quadrupole component adversely affects the beam. We have designed a mode launcher free of this disadvantage. We present design considerations, methodology, and an example S-band mode launcher.
Funding DOE SCGSR and DOE/SU Contract DE-AC02-76-SF00515
Paper download MOPMW039.PDF [0.625 MB / 3 pages]
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Conference IPAC2016, Busan, Korea
Series International Particle Accelerator Conference (7th)
Proceedings Link to full IPAC2016 Proccedings
Session Poster Session
Date 09-May-16   16:00–18:00
Main Classification 07 Accelerator Technology
Sub Classification T06 Room Temperature RF
Keywords quadrupole, gun, electron, impedance, cavity
Publisher JACoW, Geneva, Switzerland
Editors Christine Petit-Jean-Genaz (CERN, Geneva, Switzerland); Dong Eon Kim (PAL, Pohang, Republic of Korea); Kyung Sook Kim (PAL, Pohang, Republic of Korea); In Soo Ko (POSTECH, Pohang, Republic of Korea); Volker RW Schaa (GSI, Darmstadt, Germany)
ISBN 978-3-95450-147-2
Published June 2016
Copyright
Copyright © 2016 by JACoW, Geneva, Switzerland     CC-BY Creative Commons License
cc Creative Commons Attribution 3.0