The Spallation Neutron Source operates reliably at 1.2 MW and will gradually ramp to 1.4 MW. This paper briefly recalls some of the struggles when the unprecedented project was started and ramped to 1 MW over a 3½ year period. This was challenging, especially for the H− ion source and the low-energy beam transport system, which make up the H− injector. It took several more years to push the H− injector to the 1.4 MW requirements, and even longer to reach close to 100% injector availability. An additional breakthrough was the carefully staged, successful extension of the H− source service cycle so that disruptive source changes became rare events. More than 7 A·h of extracted H− ions have been demonstrated with a single source without maintenance, more than twice the single-source quantity of ions produced by any other high-current H− accelerator facility. Achieving the 1.4 MW requirements with close to 100% availability and record-breaking source service cycles were the basis for the 2017 Brightness Award.
REFERENCES
1.
J. M.
Carpenter
and C.-K.
Loong
, Elements of Slow–Neutron Scattering
(Cambridge University Press
, 2015
).2.
S.
Henderson
et al., “The spallation neutron source accelerator system design
,” Nucl. Instrum. Methods Phys. Res., Sect. A
763
, 610
–673
(2014
).3.
J. R.
Alonso
, “High-current, negative-ion sources for pulsed spallation neutron sources: LBNL Workshop, October 1994
,” Rev. Sci. Instrum.
67
, 1308
–1313
(1996
).4.
R. F.
Welton
, “Overview of high-brightness H− ion sources
,” in Proceedings of LINAC 2002
(Pohang Accelerator Laboratory
, 2002
), pp. 559
–563
.5.
J. G.
Alessi
, “Performance of the magnetron H− source on the BNL 200 MeV linac
,” AIP Conf. Proc.
CP642
, 279
–281
(2002
).6.
W. B.
Ingalls
, J. E.
Stelzer
, and H. E.
Williams
III, “Recent operating experience with the H− injector at LAMPF/LANSCE
,” in Proceedings of LINAC 96
(CERN Desktop Publishing Service
, 1996
), pp. 704
–706
.7.
R.
Keller
, D.
Cheng
, R.
DiGennaro
, R. A.
Gough
, J.
Greer
, K. N.
Leung
, A.
Ratti
, J.
Reijonen
, R. W.
Thomae
, T.
Schenkel
, J. W.
Staples
, R.
Yourd
, A.
Aleksandrov
, M. P.
Stockli
, and R. W.
Welton
, “Ion-source and low-energy beam-transport issues with the front-end systems for the spallation neutron source
,” Rev. Sci. Instrum.
73
, 914
–916
(2002
).8.
M. P.
Stockli
, “The development of high-current and high duty-factor H− Injectors
,” in Proceedings of LINAC 06
(Spallation Neutron Source and JACoW
, 2006
), pp. 213
–217
.9.
K.
Saadatmand
, G.
Arbique
, J.
Hebert
, and R.
Valicenti
, “Performance of a high current H− radio frequency volume ion source
,” Rev. Sci. Instrum.
67
, 1318
–1320
(1996
).10.
J.
Peters
, “Negative ion sources for high energy accelerators
,” Rev. Sci. Instrum.
71
, 1069
–1074
(2000
).11.
M. P.
Stockli
, “Volume and surface-enhanced volume negative ion sources
,” in Proceedings of CERN Accelerator School on Ion Sources, Senec, Slovakia, 2012
, edited by R.
Bailey
(CERN
, 2013
), pp. 265
–284
, Report CERN-2013-007.12.
J.
Peters
, “Internal versus external RF coupling into a volume source
,” in Proceedings of EPAC 02
, (JACoW
, 2002
), pp. 1727
–1729
.13.
J.
Peters
, “The HERA RF-driven multicusp H− ion source
,” in Proceedings of LINAC 06
(Spallation Neutron Source and JACoW
, 2006
), pp. 388
–390
.14.
R. F.
Welton
, A.
Aleksandrov
, B. X.
Han
, Y. W.
Kang
, M. M.
Middendorf
, S. N.
Murray
, M.
Piller
, T. R.
Pennisi
, V.
Peplov
, R.
Saethre
, M.
Santana
, C.
Stinson
, and M. P.
Stockli
, “A new 2.5 MeV injector and beam test facility for the spallation neutron source
,” AIP Conf. Proc.
CP1869
, 060002-1
–060002-8
(2017
).15.
J.
Lettry
et al., “Linac4 H− ion sources
,” Rev. Sci. Instrum.
87
, 02B139-1
–02B139-3
(2016
).16.
M. A.
Leitner
, R. A.
Gough
, K. N.
Leung
, M. L.
Rickard
, P. K.
Scott
, A. B.
Wengrow
, M. D.
Williams
, and D. C.
Wutte
, “Development of the radio frequency driven H− ion source for the national spallation neutron source
,” Rev. Sci. Instrum.
69
, 962
–964
(1998
).17.
J.
Reijonen
, R.
Thomae
, and R.
Keller
, “Evolution of the LEBT layout for SNS
,” in Proceedings of LINAC 2000
(Stanford Linear Accelerator Center, Stanford, California
, 2000
), pp. 253
–255
.18.
J.
Staples
, D.
Cheng
, M.
Fong
, J.
Greer
, M.
Hoff
, R.
Keller
, K.
Kennedy
, M.
Leitner
, R.
MacGill
, D.
Oshatz
, A.
Ratti
, J.
Remais
, and S.
Virostek
, “The SNS front end accelerator systems
,” in Proceedings of LINAC 98
(Argonne National Laboratory, ANL-98/28
, 1998
), pp. 177
–179
.19.
K. N.
Leung
, “The application and status of the radio frequency driven multi-cusp ion source
,” Rev. Sci. Instrum.
71
, 1064
–1068
(2000
).20.
D.
Wutte
, J.
Burke
, B.
Fujikawa
, P.
Fetter
, S. J.
Freedman
, R. A.
Gough
, C. M.
Lyneis
, and Z. Q.
Xie
, “Development of a radioactive ion beam test stand at LBNL
,” AIP Conf. Proc.
CP473
, 566
–577
(1999
).21.
J.
Reijonen
, M.
Eardley
, R.
Gough
, R.
Keller
, K.
Leung
, R.
Thomae
, D.
Pickard
, and M. D.
Williams
, “Improvement of the lifetime of radio frequency antenna for plasma generation
,” Rev. Sci. Instrum.
71
, 1134
–1136
(2000
).22.
R. F.
Welton
, M. P.
Stockli
, Y.
Kang
, M.
Janney
, R.
Keller
, R. W.
Thomae
, T.
Schenkel
, and S.
Shukla
, “Ion source antenna development for the spallation neutron source
,” Rev. Sci. Instrum.
73
, 1008
–1012
(2002
).23.
Cherokee Porcelain Enamel Corporation, 2717 Independence Lane, Knoxville, TN 37914, USA.
24.
R.
Keller
, R.
Thomae
, M.
Stockli
, and R.
Welton
, “Design, operational experiences and beam results obtained with the SNS H− ion source and LEBT at Berkeley Lab
,” AIP Conf. Proc.
CP639
, 47
–60
(2002
).25.
M. P.
Stockli
, B. X.
Han
, S. N.
Murray
, D.
Newland
, T. R.
Pennisi
, M.
Santana
, and R. F.
Welton
, “Ramping up the SNS beam power with the LBNL baseline H− source
,” AIP Conf. Proc.
CP1097
, 223
–235
(2009
).26.
R. F.
Welton
, V. G.
Dudnikov
, B. X.
Han
, S. N.
Murray
, T. R.
Pennisi
, C.
Piller
, M.
Santana
, M. P.
Stockli
, and M. W.
Turvey
, “Improvements to the internal and external antenna H− ion source at the spallation neutron source
,” Rev. Sci. Instrum.
85
, 02B135-1
–02B135-5
(2014
).27.
ISIS, Rutherford Appleton Laboratory, Didcot, OX110QX, United Kingdom.
28.
M. P.
Stockli
, B. X.
Han
, S. N.
Murray
, T. R.
Pennisi
, C.
Piller
, M.
Santana
, and R. F.
Welton
, “Recent performance and ignition tests of the pulsed SNS H− source for 1 MW neutron production
,” AIP Conf. Proc.
CP1655
, 030001-1
–030001-9
(2015
).29.
M.
Bacal
and M.
Wada
, “Negative hydrogen ion production mechanisms
,” Appl. Phys. Rev.
2
, 021305-1
–021305-30
(2015
).30.
M. P.
Stockli
, B. X.
Han
, T. W.
Hardek
, Y. W.
Kang
, S. N.
Murray
, T. R.
Pennisi
, C.
Piller
, M.
Santana
, and R.
Welton
, “Producing persistent, high-current, high-duty-factor H− beams for routine 1 MW operation of the spallation neutron source
,” Rev. Sci. Instrum.
83
, 02A732-1
–02A732-7
(2012
).31.
B. X.
Han
, T.
Kalvas
, O.
Tarvainen
, R. F.
Welton
, S. N.
Murray
, Jr., T. R.
Pennisi
, M.
Santana
, and M. P.
Stockli
, “Low-energy beam transport studies supporting the spallation neutron source 1-MW beam operation
,” Rev. Sci. Instrum.
83
, 02B727-1
–02B727-4
(2012
).32.
J. W.
Staples
, M. D.
Hoff
, and C. F.
Chan
, “All-electrostatic split LEBT test results
,” in Proceedings of LINAC 96
(CERN Desktop Publishing Service
, 1996
), pp. 157
–159
.33.
M. P.
Stockli
, K. D.
Ewald
, B. X.
Han
, S. N.
Murray
, Jr., T. R.
Pennisi
, C.
Piller
, M.
Santana
, J.
Tang
, and R.
Welton
, “Recent performance of the SNS H− ion source and low-energy beam transport system
,” Rev. Sci. Instrum.
85
, 02B137-1
–02B137-4
(2014
).34.
B. X.
Han
, R. F.
Welton
, S. N.
Murray
, T. R.
Pennisi
, M.
Santana
, C. M.
Stinson
, and M. P.
Stockli
, “Refined beam measurements on the SNS H− injector
,” AIP Conf. Proc.
CP1869
, 030014-1
–030014-10
(2017
).35.
R. F.
Welton
, V. G.
Dudnikov
, K. R.
Gawne
, B. X.
Han
, S. N.
Murray
, T. R.
Pennisi
, R. T.
Roseberry
, M.
Santana
, M. P.
Stockli
, and M. W.
Turvey
, “H− radio frequency source development at the spallation neutron source
,” Rev. Sci. Instrum.
83
, 02A725-1
–02A725-4
(2012
).36.
B. X.
Han
, M. P.
Stockli
, R. F.
Welton
, S. N.
Murray
, Jr., T. R.
Pennisi
, and M.
Santana
, “Application of optical emission spectroscopy for the SNS H− ion source plasma studies
,” AIP Conf. Proc.
CP1655
, 030003-1
–030003-9
(2015
).37.
R. F.
Welton
, V. G.
Dudnikov
, B. X.
Han
, S. N.
Murray
, T. R.
Pennisi
, T. R.
Roseberry
, M.
Santana
, and M. P.
Stockli
, “Developing reliable internal antenna and standardizing performance of H− RF ion sources
,” AIP Conf. Proc.
CP1515
, 341
–348
(2013
).38.
M. P.
Stockli
, B. X.
Han
, S. N.
Murray
, Jr., T. R.
Pennisi
, M.
Santana
, C. M.
Stinson
, and R. F.
Welton
, “Record performance of and extraction studies with the spallation neutron source H− injector
,” AIP Conf. Proc.
CP1869
, 030010-1
–030010-10
(2017
).39.
B. X.
Han
, T.
Hardek
, Y.
Kang
, S. N.
Murray
, Jr., T. R.
Pennisi
, C.
Piller
, M.
Santana
, R. F.
Welton
, and M. P.
Stockli
, “Performance of the H− ion source supporting 1-MW operation at SNS
,” AIP Conf. Proc.
CP1390
, 216
–225
(2011
).40.
T.
Schenkel
, J. W.
Schenkel
, R. W.
Thomae
, J.
Reijonen
, R. A.
Gough
, K. N.
Leung
, R.
Keller
, R.
Welton
, and M.
Stockli
, “Plasma ignition schemes for the spallation neutron radio-frequency driven H− source
,” Rev. Sci. Instrum.
73
, 1017
–1019
(2002
).41.
M. P.
Stockli
, B.
Han
, S. N.
Murray
, T. R.
Pennisi
, M.
Santana
, and R.
Welton
, “Recent performance of and plasma outage studies with the SNS H− source
,” Rev. Sci. Instrum.
87
, 02B140-1
–02B140-5
(2016
).42.
B. X.
Han
, M. P.
Stockli
, Y.
Kang
, C.
Piller
, S. N.
Murray
, Jr., T. R.
Pennisi
, M.
Santana
, and R. F.
Welton
, “Characterization of the CW starter plasma RF matching network for operating the SNS H− ion source with lower H2 flows
,” Rev. Sci. Instrum.
87
, 02B143-1
–02B143-4
(2016
).43.
M. P.
Stockli
, B.
Han
, S. N.
Murray
, T. R.
Pennisi
, M.
Santana
, and R. F.
Welton
, “Ramping up the spallation neutron source beam power with the H− source using 0 mg Cs/day
,” Rev. Sci. Instrum.
81
, 02A729-1
–02A729-5
(2010
).44.
M. P.
Stockli
, “2.13 pulsed, high-current H− ion sources for future accelerators
,” in Beam Dynamics Newsletter No. 73 of the International Committee for Future Accelerators
, edited by G.
Machicoane
, P. N.
Ostroumov
, and Y. H.
Chin
(2018
), pp. 144
–157
, http://icfa-bd.kek.jp/ (unpublished).45.
M. P.
Stockli
, B. X.
Han
, S. N.
Murray
, T. R.
Pennisi
, M.
Santana
, and R. F.
Welton
, “Recent performance of the SNS H− source for 1-MW neutron production
,” AIP Conf. Proc.
CP1515
, 291
–301
(2013
).46.
M. P.
Stockli
et al., “Workshop on performance variations in H− ion sources 2012: PV H−12
,” AIP Conf. Proc.
CP1515
, 594
–597
(2013
).47.
J. R.
Alonso
, “Announcement: The 2017 Winners of the Brightness Award
,” Rev. Sci. Instrum.
89
, 052201
(2018
).© 2018 Author(s).
2018
Author(s)
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