SRF2011 - List of Authors (Kelly, M.P.)

Paper

Title

Page

β = 0.285 Half-Wave Resonator for FRIB

132

P.N. Ostroumov, Z.A. Conway, R.L. Fischer, S.M. Gerbick, M.P. Kelly, A. Kolomiets, B. Mustapha, A. Ortega Bergado
ANL, Argonne, USA

Funding: This work was supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357and WFO 85Y64 Supported by Michigan State University
We have developed an optimized electromagnetic and mechanical design of a 322 MHz half-wave resonator (HWR) suitable for acceleration of ions in the post-stripper section of the Facility for Rare Isotope Beams (FRIB). The cavity design is based on recent advances in SRF technology for TEM-class structures being developed at ANL. Highly optimized EM parameters were achieved using an ”hourglass” cavity shape for the HWR. This new design will be processed with a new HWR horizontal electropolishing system after all mechanical work on the cavity including the welding of the helium vessel is complete. Recently, this procedure was successfully tested on a quarter wave resonator developed for the ATLAS Upgrade which achieved peak surface fields of 70 MV/m and 10⁵ mT. Following these results we propose to operate the HWR with a 2.6 MV accelerating voltage per cavity at the optimal ion velocity of β = 0.285. Fabrication of the cavity can be started immediately as soon as funding is available.

TUPO021

Current State of Electropolishing at ANL

408

T. Reid, S.M. Gerbick, M.P. Kelly, R.C. Murphy
ANL, Argonne, USA

An electropolishing system for 1.3 GHz elliptical single- and 9-cell cavities is in full operation at the joint ANL/FNAL Superconducting Cavity Surface Processing Facility (SCSPF) located at Argonne. Currently, the facility is processing an average of one cavity per week. Single cell cavities are routinely achieving accelerating gradients exceeding 35 MV/m and several recent 9-cell cavities have operated in the region of 35-38 MV/m. Process improvements are continuing with the intent to improve overall yield at 35 MV/m and to improve cavity Q-values. In particular, cavity rf losses at the level of ~5 nOhm in both the low- and medium field regions appear to be sensitive to relatively small changes in EP parameters. Some examples of this are presented here. Finally, electropolishing on dressed 9-cell cavities is being explored as a technique for recovering previously good performing bare cavities where performance has degraded, for example, after rf processing.

TUPO034

A Flexible System for the High Pressure Rinsing of SRF Cavities

456

R.C. Murphy, S.M. Gerbick, M. Kedzie, M.P. Kelly, T. Reid
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.
The Physics Division SRF group at Argonne National Laboratory is building a new, high pressure rinse system for the joint ANL/FNAL Superconducting Cavity Surface Processing Facility (SCSPF). The rinsing tool can be easily reconfigured vertically or horizontally to process a variety of SRF cavity shapes and sizes including elliptical, spoke, quarter- and half-wave cavities. The system has been commissioned with a new 72 MHz β=0.077 quarter wave cavity as part of the ATLAS Intensity Upgrade at ANL. The tool is also designed to rinse 1.3 GHz elliptical single-cell and 9-cell cavities, as well as the new 650 MHz elliptical cavities under development for Project-X and Fermilab. This work was supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357.

WEIOA03

A New Electropolishing System For Low-Beta SC Cavities

576

S.M. Gerbick, M.P. Kelly, R.C. Murphy, T. Reid
ANL, Argonne, USA

A new electropolishing system designed for a completed low-beta niobium SC cavity with integral helium vessel was installed and operated at Argonne National Laboratory. The design was based on that used for the electropolishing of 1.3 GHz 9-cell elliptical cavities for the global ILC development effort at ANL, with the addition of direct water cooling to the cavity surface. This design also allows for repeated chemistry on the cavity, if needed, without producing the rougher surface associated with buffered chemical polishing.

Slides WEIOA03 [2.463 MB]

THIOB04

SRF Advances for ATLAS and other β<1 Applications

680

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

The guiding principle for the design of the new 72 MHz quarter wave SC cavities at Argonne was to provide the maximum possible accelerating gradient along the linac with large acceptance and minimal beam losses. Cavities will be installed into ATLAS in 2012 as the beam intensity upgrade, but are also intended for the next generation of ion linacs to be used in basic and applied science and technology. State-of-the-art cavity designs and fabrication techniques developed at ANL have been applied to the construction of the first prototype. Tests of the prototype 72 MHz QWR demonstrate the highest performance achieved to date for this class of cavity designed to cover the velocity range 0.06<β<0.12. The cavity has very low RF losses and the highest accelerating gradients ever achieved for any quarter-wave structure. Indeed, the accelerating voltage of 4.3 MV is roughly four times higher than that reported for the best SC cavities in this velocity range currently in operation at any facility worldwide. Also, this demonstrated 4.3 MV accelerating voltage substantially exceeds the 2.5 MV design voltage.

Slides THIOB04 [3.571 MB]

FRIOA02

Innovative Tuner Designs For Low Beta SRF Cavities

943

Z.A. Conway, M.P. Kelly, P.N. Ostroumov
ANL, Argonne, USA
K.W. Shepard
TechSource, Los Alamos, NM, USA

This presentation will give an overview of innovative low-beta (0.05 < beta < 0.6) cavity frequency tuners for heavy-ion accelerators. These cavities typically operate with microphonic induced frequency perturbations which are a significant fraction of the loaded bandwidth. If uncompensated these frequency variations may unnecessarily increase the RF power required to stabilize the phase and amplitude of the cavity RF fields. Several tuner designs with operating details will be reviewed.

Slides FRIOA02 [3.112 MB]

Paper	Title	Page
MOPO026	β = 0.285 Half-Wave Resonator for FRIB	132
	P.N. Ostroumov, Z.A. Conway, R.L. Fischer, S.M. Gerbick, M.P. Kelly, A. Kolomiets, B. Mustapha, A. Ortega Bergado ANL, Argonne, USA
	Funding: This work was supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357and WFO 85Y64 Supported by Michigan State University We have developed an optimized electromagnetic and mechanical design of a 322 MHz half-wave resonator (HWR) suitable for acceleration of ions in the post-stripper section of the Facility for Rare Isotope Beams (FRIB). The cavity design is based on recent advances in SRF technology for TEM-class structures being developed at ANL. Highly optimized EM parameters were achieved using an ”hourglass” cavity shape for the HWR. This new design will be processed with a new HWR horizontal electropolishing system after all mechanical work on the cavity including the welding of the helium vessel is complete. Recently, this procedure was successfully tested on a quarter wave resonator developed for the ATLAS Upgrade which achieved peak surface fields of 70 MV/m and 10⁵ mT. Following these results we propose to operate the HWR with a 2.6 MV accelerating voltage per cavity at the optimal ion velocity of β = 0.285. Fabrication of the cavity can be started immediately as soon as funding is available.

TUPO021	Current State of Electropolishing at ANL	408
	T. Reid, S.M. Gerbick, M.P. Kelly, R.C. Murphy ANL, Argonne, USA
	An electropolishing system for 1.3 GHz elliptical single- and 9-cell cavities is in full operation at the joint ANL/FNAL Superconducting Cavity Surface Processing Facility (SCSPF) located at Argonne. Currently, the facility is processing an average of one cavity per week. Single cell cavities are routinely achieving accelerating gradients exceeding 35 MV/m and several recent 9-cell cavities have operated in the region of 35-38 MV/m. Process improvements are continuing with the intent to improve overall yield at 35 MV/m and to improve cavity Q-values. In particular, cavity rf losses at the level of ~5 nOhm in both the low- and medium field regions appear to be sensitive to relatively small changes in EP parameters. Some examples of this are presented here. Finally, electropolishing on dressed 9-cell cavities is being explored as a technique for recovering previously good performing bare cavities where performance has degraded, for example, after rf processing.

TUPO034	A Flexible System for the High Pressure Rinsing of SRF Cavities	456
	R.C. Murphy, S.M. Gerbick, M. Kedzie, M.P. Kelly, T. Reid 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. The Physics Division SRF group at Argonne National Laboratory is building a new, high pressure rinse system for the joint ANL/FNAL Superconducting Cavity Surface Processing Facility (SCSPF). The rinsing tool can be easily reconfigured vertically or horizontally to process a variety of SRF cavity shapes and sizes including elliptical, spoke, quarter- and half-wave cavities. The system has been commissioned with a new 72 MHz β=0.077 quarter wave cavity as part of the ATLAS Intensity Upgrade at ANL. The tool is also designed to rinse 1.3 GHz elliptical single-cell and 9-cell cavities, as well as the new 650 MHz elliptical cavities under development for Project-X and Fermilab. This work was supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357.

WEIOA03	A New Electropolishing System For Low-Beta SC Cavities	576
	S.M. Gerbick, M.P. Kelly, R.C. Murphy, T. Reid ANL, Argonne, USA
	A new electropolishing system designed for a completed low-beta niobium SC cavity with integral helium vessel was installed and operated at Argonne National Laboratory. The design was based on that used for the electropolishing of 1.3 GHz 9-cell elliptical cavities for the global ILC development effort at ANL, with the addition of direct water cooling to the cavity surface. This design also allows for repeated chemistry on the cavity, if needed, without producing the rougher surface associated with buffered chemical polishing.
	Slides WEIOA03 [2.463 MB]

THIOB04	SRF Advances for ATLAS and other β<1 Applications	680
	M.P. Kelly, Z.A. Conway, S.M. Gerbick, M. Kedzie, R.C. Murphy, B. Mustapha, P.N. Ostroumov, T. Reid ANL, Argonne, USA
	The guiding principle for the design of the new 72 MHz quarter wave SC cavities at Argonne was to provide the maximum possible accelerating gradient along the linac with large acceptance and minimal beam losses. Cavities will be installed into ATLAS in 2012 as the beam intensity upgrade, but are also intended for the next generation of ion linacs to be used in basic and applied science and technology. State-of-the-art cavity designs and fabrication techniques developed at ANL have been applied to the construction of the first prototype. Tests of the prototype 72 MHz QWR demonstrate the highest performance achieved to date for this class of cavity designed to cover the velocity range 0.06<β<0.12. The cavity has very low RF losses and the highest accelerating gradients ever achieved for any quarter-wave structure. Indeed, the accelerating voltage of 4.3 MV is roughly four times higher than that reported for the best SC cavities in this velocity range currently in operation at any facility worldwide. Also, this demonstrated 4.3 MV accelerating voltage substantially exceeds the 2.5 MV design voltage.
	Slides THIOB04 [3.571 MB]

FRIOA02	Innovative Tuner Designs For Low Beta SRF Cavities	943
	Z.A. Conway, M.P. Kelly, P.N. Ostroumov ANL, Argonne, USA K.W. Shepard TechSource, Los Alamos, NM, USA
	This presentation will give an overview of innovative low-beta (0.05 < beta < 0.6) cavity frequency tuners for heavy-ion accelerators. These cavities typically operate with microphonic induced frequency perturbations which are a significant fraction of the loaded bandwidth. If uncompensated these frequency variations may unnecessarily increase the RF power required to stabilize the phase and amplitude of the cavity RF fields. Several tuner designs with operating details will be reviewed.
	Slides FRIOA02 [3.112 MB]