2011 Particle Accelerator Conference - List of Authors (Gerbick, S.M.)

Paper

Title

Page

Superconducting 72 MHz β=0.077 Quarter-wave Cavity for ATLAS

892

M.P. Kelly, Z.A. Conway, S.M. Gerbick, M. Kedzie, R.C. Murphy, P.N. Ostroumov, T. Reid
ANL, Argonne, USA

A 72 MHz superconducting (SC) niobium quarter-wave cavity (QWR) optimized for β=0.077 has been built and tested as part of a beam intensity upgrade of the ATLAS SC heavy-ion linac. The two-gap cavity, designed to accelerate ions over the velocity range 0.06<β<0.12 and provide 2.5 MV of accelerating voltage per cavity at T=4.5 Kelvin, is based on a highly optimized electromagnetic design to reduce surface electric and magnetic fields. Horizontal electropolishing on the complete cavity with the helium jacket, is similar to that performed on 1.3 GHz ILC-type cavities and is a first for a low-β TEM cavity. This development is part of a broader effort to demonstrate ~120 mT surface fields with Rs~5 nΩ in 2 K operation for low-β cavities with the aim of substantially reducing the footprint for future ion linacs. First rf cold test results show the highest accelerating gradients (13.4 MV/m, leff=βλ) and voltage/cavity (4.3 MV) achieved for this class of SC cavity.

THOCN5

ATLAS Upgrade

2110

P.N. Ostroumov, A. Barcikowski, Z.A. Conway, S.M. Gerbick, M. Kedzie, M.P. Kelly, S.W.T. MacDonald, B. Mustapha, R.C. Pardo, S.I. Sharamentov
ANL, Argonne, USA

Funding: This work was supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357.
ATLAS (Argonne Tandem Linac Accelerator System) upgrade requires several substantial developments in accelerator technologies, such as CW heavy ion RFQ and high-performance cryomodule with low-beta cavities. The upgrade project is well advanced. The physics and engineering design of the RFQ are complete and fabrication of OFE copper parts is in progress. The 3.9-meter length RFQ is composed from 5 strongly coupled segments. High-temperature furnace brazing of the segments is planned for the summer of 2011. The RFQ design includes several innovative features such as trapezoidal vane tip modulation, compact output radial matcher to form an axially symmetric beam. The upgrade project also includes development and construction of a cryomodule containing seven 72.75 MHz SC quarter wave cavities designed for the geometrical β= 0.077 and four SC solenoids. The cavity is designed to obtain an accelerating voltage higher than 2.5 MV. The prototype cavity together with high-power capacitive coupler and piezoelectric tuner has been developed, fabricated and is being tested. This paper reports innovative design features of both RFQ and SRF linac and current status of the project.

Slides THOCN5 [3.070 MB]

Paper	Title	Page
TUP046	Superconducting 72 MHz β=0.077 Quarter-wave Cavity for ATLAS	892
	M.P. Kelly, Z.A. Conway, S.M. Gerbick, M. Kedzie, R.C. Murphy, P.N. Ostroumov, T. Reid ANL, Argonne, USA
	A 72 MHz superconducting (SC) niobium quarter-wave cavity (QWR) optimized for β=0.077 has been built and tested as part of a beam intensity upgrade of the ATLAS SC heavy-ion linac. The two-gap cavity, designed to accelerate ions over the velocity range 0.06<β<0.12 and provide 2.5 MV of accelerating voltage per cavity at T=4.5 Kelvin, is based on a highly optimized electromagnetic design to reduce surface electric and magnetic fields. Horizontal electropolishing on the complete cavity with the helium jacket, is similar to that performed on 1.3 GHz ILC-type cavities and is a first for a low-β TEM cavity. This development is part of a broader effort to demonstrate ~120 mT surface fields with Rs~5 nΩ in 2 K operation for low-β cavities with the aim of substantially reducing the footprint for future ion linacs. First rf cold test results show the highest accelerating gradients (13.4 MV/m, leff=βλ) and voltage/cavity (4.3 MV) achieved for this class of SC cavity.

THOCN5	ATLAS Upgrade	2110
	P.N. Ostroumov, A. Barcikowski, Z.A. Conway, S.M. Gerbick, M. Kedzie, M.P. Kelly, S.W.T. MacDonald, B. Mustapha, R.C. Pardo, S.I. Sharamentov ANL, Argonne, USA
	Funding: This work was supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357. ATLAS (Argonne Tandem Linac Accelerator System) upgrade requires several substantial developments in accelerator technologies, such as CW heavy ion RFQ and high-performance cryomodule with low-beta cavities. The upgrade project is well advanced. The physics and engineering design of the RFQ are complete and fabrication of OFE copper parts is in progress. The 3.9-meter length RFQ is composed from 5 strongly coupled segments. High-temperature furnace brazing of the segments is planned for the summer of 2011. The RFQ design includes several innovative features such as trapezoidal vane tip modulation, compact output radial matcher to form an axially symmetric beam. The upgrade project also includes development and construction of a cryomodule containing seven 72.75 MHz SC quarter wave cavities designed for the geometrical β= 0.077 and four SC solenoids. The cavity is designed to obtain an accelerating voltage higher than 2.5 MV. The prototype cavity together with high-power capacitive coupler and piezoelectric tuner has been developed, fabricated and is being tested. This paper reports innovative design features of both RFQ and SRF linac and current status of the project.
	Slides THOCN5 [3.070 MB]