NAPAC2016 - List of Authors (Kang, Y.W.)

Paper	Title	Page
MOPOB71	Consideration on Determination of Coupling Factors of Waveguide Iris Couplers	229
	S.W. Lee, M.S. Champion, Y.W. Kang ORNL, Oak Ridge, Tennessee, USA
	Funding: This work was supported by SNS through UTBattelle, LLC, under contract DEAC0500OR22725 for the U.S.DOE. Waveguide iris couplers are frequently used to power accelerating cavities in low beta sections of ion accelerators. In ORNL Spallation Neutron Source (SNS), six drift tube linac (DTL) cavity structures have been operating. An iris input coupler with a tapered ridge waveguide and a waveguide ceramic disk window feeds each cavity. The original couplers and cavities have been in service for more than a decade. Since all DTL cavity structures are fully utilized for neutron production, none of the cavity structures is available as a test cavity or a spare. Maintaining spares of the iris couplers for operations and future system upgrade without using the full DTL structure, a test setup for precision tuning is needed. A smaller single-cell cavity may be used for pretuning of the coupling irises as the test cavity and high power RF conditioning of the iris couplers as the bridge waveguide. In this paper, study of using a single-cell cavity for the iris tuning and the conditioning is presented with 3D simulations. A single-cell test cavity has been built and used for low power bench measurement with the iris couplers to demonstrate the approach.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-MOPOB71
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WEPOA52	Modeling and Simulation of RFQs for Analysis of Fields and Frequency Deviations with Respect to Internal Dimensional Errors	810
	Y.W. Kang, S.W. Lee ORNL, Oak Ridge, Tennessee, USA
	Funding: This work was supported by SNS through UTBattelle, LLC, under contract DEAC0500OR22725 for the U.S.DOE. Performance of radio frequency quadrupole (RFQ) is sensitive to the errors in internal dimensions which shift resonance frequency and distort field distribution on the beam axis along the structure. The SNS RFQ has been retuned three times to compensate the deviations in frequency and field flatness with suspected dimensional changes since the start of the project for continuous operation with H⁻ ion beams. SNS now has a new RFQ as a spare that is installed in beam test facility (BTF), a low energy test accelerator. In order to understand and predict the performance deviation, full 3D modeling and simulation were performed for the SNS RFQs. Field and frequency errors from hypothetical transverse vane perturbations, and vane erosion (and metal deposition such as Cesium introduced by the ion source operation) at the low energy ends are discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-WEPOA52
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

Consideration on Determination of Coupling Factors of Waveguide Iris Couplers

229

S.W. Lee, M.S. Champion, Y.W. Kang
ORNL, Oak Ridge, Tennessee, USA

Funding: This work was supported by SNS through UTBattelle, LLC, under contract DEAC0500OR22725 for the U.S.DOE.
Waveguide iris couplers are frequently used to power accelerating cavities in low beta sections of ion accelerators. In ORNL Spallation Neutron Source (SNS), six drift tube linac (DTL) cavity structures have been operating. An iris input coupler with a tapered ridge waveguide and a waveguide ceramic disk window feeds each cavity. The original couplers and cavities have been in service for more than a decade. Since all DTL cavity structures are fully utilized for neutron production, none of the cavity structures is available as a test cavity or a spare. Maintaining spares of the iris couplers for operations and future system upgrade without using the full DTL structure, a test setup for precision tuning is needed. A smaller single-cell cavity may be used for pretuning of the coupling irises as the test cavity and high power RF conditioning of the iris couplers as the bridge waveguide. In this paper, study of using a single-cell cavity for the iris tuning and the conditioning is presented with 3D simulations. A single-cell test cavity has been built and used for low power bench measurement with the iris couplers to demonstrate the approach.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-MOPOB71

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPOA52

Modeling and Simulation of RFQs for Analysis of Fields and Frequency Deviations with Respect to Internal Dimensional Errors

810

Y.W. Kang, S.W. Lee
ORNL, Oak Ridge, Tennessee, USA

Funding: This work was supported by SNS through UTBattelle, LLC, under contract DEAC0500OR22725 for the U.S.DOE.
Performance of radio frequency quadrupole (RFQ) is sensitive to the errors in internal dimensions which shift resonance frequency and distort field distribution on the beam axis along the structure. The SNS RFQ has been retuned three times to compensate the deviations in frequency and field flatness with suspected dimensional changes since the start of the project for continuous operation with H⁻ ion beams. SNS now has a new RFQ as a spare that is installed in beam test facility (BTF), a low energy test accelerator. In order to understand and predict the performance deviation, full 3D modeling and simulation were performed for the SNS RFQs. Field and frequency errors from hypothetical transverse vane perturbations, and vane erosion (and metal deposition such as Cesium introduced by the ion source operation) at the low energy ends are discussed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-WEPOA52

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)