SRF2013 - List of Authors (Kim, S.-H.)

Paper	Title	Page
MOP002	Conceptual Design for Replacement of the DTL and CCL with Superconducting RF Cavities in the Spallation Neutron Source Linac	69
	M.S. Champion, M. Doleans, S.-H. Kim ORNL, Oak Ridge, Tennessee, USA
	Funding: ORNL is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy. The Spallation Neutron Source Linac utilizes normal conducting RF cavities in the low energy section from 2.5 MeV to 186 MeV. Six Drift Tube Linac (DTL) structures accelerate the beam to 87 MeV, and four Coupled Cavity Linac (CCL) structures provide further acceleration to 186 MeV. The remainder of the Linac is comprised of 81 superconducting cavities packaged in 23 cryomodules to provide a final beam energy of approximately 1 GeV. The superconducting Linac has proven to be substantially more reliable than the normal conducting Linac despite the greater number of stations and the complexity associated with the cryogenic plant and distribution. A conceptual design has been initiated on a replacement of the DTL and CCL with superconducting RF cavities. The motivation, constraints, and conceptual design are presented.

MOP007	The Status of Superconducting Linac and SRF Activities at the SNS	83
	S.-H. Kim, W. Blokland, M.S. Champion, A. Coleman, M.T. Crofford, M. Doleans, D.L. Douglas, T.V. Gorlov, M.P. Howell, Y.W. Kang, A.P. Shishlo, S.E. Stewart, W.H. Strong ORNL, Oak Ridge, Tennessee, USA R. Afanador, B. DeGraff, B.S. Hannah, S.W. Lee, C.J. McMahan, T.S. Neustadt, S.W. Ottaway, C.C. Peters, J. Saunders, D.M. Vandygriff ORNL RAD, Oak Ridge, Tennessee, USA
	Funding: This work was supported by SNS through UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. DOE. There have been substantial gains at the Spallation Neutron Source (SNS) in last 7 years in understanding pulsed superconducting linac (SCL) operation including system and equipment limiting factors and resolution of system and equipment issues. Significant effort and focus are required to assure ongoing success of the operation, maintenance and improvement of the SCL, and to address the requirements of the upgrade project in the future. The SNS is taking a multi-faceted approach to maintaining and improving its linac. A balanced set of facilities which support processing, assembly, repair, and testing of cavities/cryomodules are currently being placed into service. This paper summarizes the status of the SNS SCL and related superconducting radio-frequency (SRF) activities such as development of ASME code-stamped spare cryomodules, R&D activities for SRF cavity performance improvements, SRF cavity development for power upgrade project and SRF facility development/upgrade to support all required activities.

TUP057	Plasma Processing R&D for the SNS Superconducting Linac RF Cavities	551
	M. Doleans, W. Blokland, M.T. Crofford, D.L. Douglas, M.P. Howell, S.-H. Kim, P.V. Tyagi ORNL, Oak Ridge, Tennessee, USA R. Afanador, J.A. Ball, B. DeGraff, B.S. Hannah, S.W. Lee, C.J. McMahan, J. Saunders ORNL RAD, Oak Ridge, Tennessee, USA
	Funding: This work was supported by SNS through UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. DOE The Spallation Neutron Source routinely operates with a proton beam power of 1 MW on its production target. A plan to reach the design 1.4 MW within a few years is in place* and relies on increasing the ion beam current, pulse length and beam energy in the linac. The increase in beam energy from the present 930 MeV to 1 GeV will require an increase of approximately 15% in the accelerating gradient of the superconducting linac high-beta cryomodules. In-situ plasma processing was identified as a promising technique** to reduce electron activity in the SNS superconducting cavities and increase their accelerating gradient. R&D on plasma processing aims at deploying the new in-situ technique in the linac tunnel by 2016. Overall plan and current status of the plasma processing R&D will be presented. * NScD Five year plan 2012-2016, SNS-NSCD-EXE-PN-0001, R00, ORNL ** S-H Kim et al., “R&D Status for In-Situ Plasma Surface Cleaning of SRF Cavities at Spallation Neutron Source”, PAC 2011 Proceedings

Paper

Title

Page

Conceptual Design for Replacement of the DTL and CCL with Superconducting RF Cavities in the Spallation Neutron Source Linac

69

M.S. Champion, M. Doleans, S.-H. Kim
ORNL, Oak Ridge, Tennessee, USA

Funding: ORNL is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy.
The Spallation Neutron Source Linac utilizes normal conducting RF cavities in the low energy section from 2.5 MeV to 186 MeV. Six Drift Tube Linac (DTL) structures accelerate the beam to 87 MeV, and four Coupled Cavity Linac (CCL) structures provide further acceleration to 186 MeV. The remainder of the Linac is comprised of 81 superconducting cavities packaged in 23 cryomodules to provide a final beam energy of approximately 1 GeV. The superconducting Linac has proven to be substantially more reliable than the normal conducting Linac despite the greater number of stations and the complexity associated with the cryogenic plant and distribution. A conceptual design has been initiated on a replacement of the DTL and CCL with superconducting RF cavities. The motivation, constraints, and conceptual design are presented.

MOP007

The Status of Superconducting Linac and SRF Activities at the SNS

83

S.-H. Kim, W. Blokland, M.S. Champion, A. Coleman, M.T. Crofford, M. Doleans, D.L. Douglas, T.V. Gorlov, M.P. Howell, Y.W. Kang, A.P. Shishlo, S.E. Stewart, W.H. Strong
ORNL, Oak Ridge, Tennessee, USA
R. Afanador, B. DeGraff, B.S. Hannah, S.W. Lee, C.J. McMahan, T.S. Neustadt, S.W. Ottaway, C.C. Peters, J. Saunders, D.M. Vandygriff
ORNL RAD, Oak Ridge, Tennessee, USA

Funding: This work was supported by SNS through UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. DOE.
There have been substantial gains at the Spallation Neutron Source (SNS) in last 7 years in understanding pulsed superconducting linac (SCL) operation including system and equipment limiting factors and resolution of system and equipment issues. Significant effort and focus are required to assure ongoing success of the operation, maintenance and improvement of the SCL, and to address the requirements of the upgrade project in the future. The SNS is taking a multi-faceted approach to maintaining and improving its linac. A balanced set of facilities which support processing, assembly, repair, and testing of cavities/cryomodules are currently being placed into service. This paper summarizes the status of the SNS SCL and related superconducting radio-frequency (SRF) activities such as development of ASME code-stamped spare cryomodules, R&D activities for SRF cavity performance improvements, SRF cavity development for power upgrade project and SRF facility development/upgrade to support all required activities.

TUP057

Plasma Processing R&D for the SNS Superconducting Linac RF Cavities

551

M. Doleans, W. Blokland, M.T. Crofford, D.L. Douglas, M.P. Howell, S.-H. Kim, P.V. Tyagi
ORNL, Oak Ridge, Tennessee, USA
R. Afanador, J.A. Ball, B. DeGraff, B.S. Hannah, S.W. Lee, C.J. McMahan, J. Saunders
ORNL RAD, Oak Ridge, Tennessee, USA

Funding: This work was supported by SNS through UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. DOE
The Spallation Neutron Source routinely operates with a proton beam power of 1 MW on its production target. A plan to reach the design 1.4 MW within a few years is in place* and relies on increasing the ion beam current, pulse length and beam energy in the linac. The increase in beam energy from the present 930 MeV to 1 GeV will require an increase of approximately 15% in the accelerating gradient of the superconducting linac high-beta cryomodules. In-situ plasma processing was identified as a promising technique** to reduce electron activity in the SNS superconducting cavities and increase their accelerating gradient. R&D on plasma processing aims at deploying the new in-situ technique in the linac tunnel by 2016. Overall plan and current status of the plasma processing R&D will be presented.
* NScD Five year plan 2012-2016, SNS-NSCD-EXE-PN-0001, R00, ORNL
** S-H Kim et al., “R&D Status for In-Situ Plasma Surface Cleaning of SRF Cavities at Spallation Neutron Source”, PAC 2011 Proceedings