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Slow Waveguide Structures for Particle Accelerators

Oak Ridge National Laboratory

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Technology Marketing SummaryA waveguide design that can save time and money in the construction and tuning of
a particle accelerator was developed by ORNL researchers. Particle accelerators use
electromagnetic fields to propel charged particles to high speeds within a well-defined
beam. The beam line is used for basic science investigations as well as for applications
in biotechnology and energy. This invention can be used in normal conducting and
superconducting accelerators.

DescriptionAcceleration of charged particles, such as protons, requires a radio frequency
waveguide structure to support transmission of particles at speeds slower than
the speed of light. Conventional waveguide designs use a multi-cell structure with
corrugations along the beam axis. This method requires expensive construction
techniques in addition to tuning of individual cells.

The ORNL invention instead uses a waveguide structure with a helical twist for this
purpose. This tool is much simpler to construct since there is no variation in the
shape of the transversal cross section along the axis of the structure Additionally, this
approach does not require tuning of individual cells since the field and frequency of
the resonant mode depend on the whole structure rather than on the individual cells.
Variation of the operating frequency or suppression of high order mode can also be
accomplished outside the resonant waveguide structure.
  • Simpler and less expensive to produce than
  • existing waveguides
  • Does not require individual cell tuning

Applications and Industries
  • Potential Applications
  • Basic and applied scientific research
  • X-ray sources for medical imaging
  • Machines for radiation treatment of cancer
More InformationPatent
Yoon W. Kang, Aly E. Fathy, and Joshua L. Wilson, Slow Wave Structures Using Twisted Waveguides for Charged Particle Applications, U.S. Patent Application 12/784,571, filed May 21, 2010.

Yoon W. Kang
Research Accelerator Division
Oak Ridge National Laboratory
Patents and Patent Applications
ID Number
Title and Abstract
Primary Lab
Patent 8,330,372
Slow wave structures using twisted waveguides for charged particle applications
A rapidly twisted electromagnetic accelerating structure includes a waveguide body having a central axis, one or more helical channels defined by the body and disposed around a substantially linear central axial channel, with central portions of the helical channels merging with the linear central axial channel. The structure propagates electromagnetic waves in the helical channels which support particle beam acceleration in the central axial channel at a phase velocity equal to or slower than the speed of light in free space. Since there is no variation in the shape of the transversal cross-section along the axis of the structure, inexpensive mechanical fabrication processes can be used to form the structure, such as extrusion, casting or injection molding. Also, because the field and frequency of the resonant mode depend on the whole structure rather than on dimensional tolerances of individual cells, no tuning of individual cells is needed. Accordingly, the overall operating frequency may be varied with a tuning/phase shifting device located outside the resonant waveguide structure.
Oak Ridge National Laboratory 12/11/2012
Technology Status
Technology IDDevelopment StageAvailabilityPublishedLast Updated

Contact ORNL About This Technology

To: David L. Sims<>