IPAC2012 - List of Authors (Virostek, S.P.)

Paper	Title	Page
THPPC033	Progress on a Cavity with Beryllium Walls for Muon Ionization Cooling Channel R&D	3356
	D.L. Bowring, A.J. DeMello, A.R. Lambert, D. Li, S.P. Virostek, M.S. Zisman LBNL, Berkeley, California, USA D.M. Kaplan Illinois Institute of Technology, Chicago, Illinois, USA R.B. Palmer BNL, Upton, Long Island, New York, USA
	Funding: Work supported by the Director, Office of Science, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. The Muon Accelerator Program (MAP) collaboration is working to develop an ionization cooling channel for future muon colliders. The ionization cooling channel requires the operation of high-gradient, normal-conducting RF cavities in solenoidal magnetic fields up to 5 T. However, experiments conducted at Fermilab's MuCool Test Area (MTA) show that increasing the solenoidal field strength reduces the maximum achievable cavity gradient. This gradient limit is characterized by an RF breakdown process that has caused significant damage to copper cavity interiors. The damage is likely caused by field-emitted electrons, focused by the solenoidal magnetic field onto small areas of the inner cavity surface. Local heating may then induce material fatigue and surface damage. Fabricating a cavity with beryllium walls would mitigate this damage due to beryllium's low density, low thermal expansion, and high electrical and thermal conductivity. This poster addresses the design and fabrication of a pillbox RF cavity with beryllium walls, in order to evaluate the performance of high-gradient cavities in strong magnetic fields.

THPPC034	Design and Analysis of the PXIE CW Radio-frequency Quadrupole (RFQ)	3359
	S.P. Virostek, M.D. Hoff, A.R. Lambert, D. Li, J.W. Staples LBNL, Berkeley, California, USA G.V. Romanov Fermilab, Batavia, USA C. Zhang IAP, Frankfurt am Main, Germany
	Funding: This work is supported by the Office of Science, United States Department of Energy under DOE contract DE-AC02-05CH11231. The Project X Injector Experiment (PXIE) will be a prototype front end of the Project X accelerator proposed by Fermilab. PXIE will consist of an H⁻ ion source, a low-energy beam transport (LEBT), a radio-frequency quadrupole (RFQ) accelerator, a medium-energy beam transport (MEBT) and a section of superconducting cryomodules that will accelerate the beam from 30 keV to 30 MeV. LBNL has developed an RFQ design for PXIE with fabrication scheduled to begin before the end of CY 2012. The chosen baseline design is a four-vane, 4.4 m long CW RFQ with a resonant frequency at 162.5 MHz (2.4 wavelengths long). The RFQ will provide bunching and acceleration of a nominal 5 mA H⁻ beam to 2.1 MeV. The relatively low wall power density results in wall power losses that are less than 100 kW. The beam dynamics design has been optimized to allow for more than 99% beam capture with exceptionally low longitudinal emittance. The RFQ mechanical design and the results of RF and thermal analyses are presented here.

THPPC035	Final Assembly and Testing of the MICE Superconducting Spectrometer Solenoids	3362
	S.P. Virostek, M.A. Green, T.O. Niinikoski, H. Pan, S. Prestemon LBNL, Berkeley, California, USA R. Preece STFC/RAL, Chilton, Didcot, Oxon, United Kingdom
	Funding: This work was supported by the Office of Science, U.S. Department of Energy under DOE contract number DE-AC02-05CH11231. The Muon Ionization Cooling Experiment (MICE) is an international effort to demonstrate the principle of ionization cooling in a segment of a realistic cooling channel using a muon beam. The experiment is sited at Rutherford Appleton Laboratory in England. A 4-tesla uniform field region at each end of the cooling channel will be provided by a pair of identical, 3-m long spectrometer solenoids. As the beam enters and exits the cooling channel, the emittance will be measured within both the upstream and downstream 400 mm diameter magnet bores. Each magnet consists of a three-coil spectrometer magnet group and a two-coil pair that matches the solenoid uniform field into the adjacent MICE cooling channel. An array of five two-stage cryocoolers and one single-stage cryocooler are used to maintain the temperature of the magnet cold mass, radiation shield and current leads. Previous testing revealed several operational and design issues related to heat leak and quench protection that have since been corrected. Details of the magnet design modifications and their final assembly as well as the results of quench training tests will be presented here.

THPPC049	Progress on the MICE 201 MHz RF Cavity at LBNL	3398
	T.H. Luo, D.J. Summers UMiss, University, Mississippi, USA A.J. DeMello, D. Li, S.P. Virostek, M.S. Zisman LBNL, Berkeley, California, USA
	The international Muon Ionization Cooling Experiment (MICE) aims at demonstrating transverse cooling of muon beams by ionization. The ionization cooling channel of MICE requires eight 201-MHz normal conducting RF cavities to compensate for the longitudinal beam energy loss in the cooling channel. In this paper, we present recent progresses on MICE RF cavity at LBNL, which includes electro-polishing, intended to improve the cavity performance in the presence of strong external magnetic field; low power RF measurements on resonant frequency and Q value of each cavity with a pair of curved- beryllium windows to terminate the cavity irises. Multipacting simulations are conducted using SLAC’s ACE-3P code to study the effects in the cavity and coupler regions with the influence by external magnetic field.

THPPP064	Project X RFQ EM Design	3883
	G.V. Romanov Fermilab, Batavia, USA M.D. Hoff, D. Li, J.W. Staples, S.P. Virostek LBNL, Berkeley, California, USA
	Project X is a proposed multi-MW proton facility at Fermi National Accelerator Laboratory (FNAL). The Project X front-end would consist of an H⁻ ion source, a low-energy beam transport (LEBT), a cw 162.5 MHz radio-frequency quadrupole (RFQ) accelerator, and a medium-energy beam transport (MEBT). Lawrence Berkeley National Laboratory (LBNL) and FNAL collaboration is currently developing the designs for various components in the Project X front end. This paper reports the detailed EM design of the cw 162.5 MHz RFQ that provides bunching of the 1-10 mA H⁻ beam with acceleration from 30 keV to 2.1 MeV.

THPPP092	Progress of the Front-End System Development for Project X at LBNL	3951
	D. Li, M.D. Hoff, Q. Ji, A.R. Lambert, T. Schenkel, J.W. Staples, S.P. Virostek LBNL, Berkeley, California, USA S. Nagaitsev, L.R. Prost, G.V. Romanov, A.V. Shemyakin Fermilab, Batavia, USA C. Zhang IAP, Frankfurt am Main, Germany
	Funding: This work is supported by the Office of Science, United States Department of Energy under DOE contract DE-AC02-05CH11231. A multi-MW proton facility, Project X has been proposed and is currently under development at Fermilab. Project X is a key accelerator complex for intensity frontier of future high energy physics programs in the US. In collaboration with Fermilab, LBNL takes the responsibility in the development and design studies of the front-end system for Project X. The front-end system would consist of H⁻ ion source(s), low-energy beam transport (LEBT), 162.5 MHz normal conducting CW Radio-Frequency-Quadrupole (RFQ) accelerator, medium-energy beam transport (MEBT), and beam chopper(s). In this paper, we will review and present recent progress of the front-end system studies, which will include the RFQ beam dynamics design, RF structure design, thermal and mechanical analyses and fabrication plan, LEBT simulation studies and concept for LEBT chopper.

THPPP093	Progress on MICE RFCC Module	3954
	D. Li, D.L. Bowring, A.J. DeMello, S.A. Gourlay, M.A. Green, N. Li, T.O. Niinikoski, H. Pan, S. Prestemon, S.P. Virostek, M.S. Zisman LBNL, Berkeley, California, USA A.D. Bross, R.H. Carcagno, V. Kashikhin, C. Sylvester Fermilab, Batavia, USA Y. Cao, S. Sun, L. Wang, L. Yin SINAP, Shanghai, People's Republic of China A.B. Chen, B. Guo, L. Li, F.Y. Xu ICST, Harbin, People's Republic of China D.M. Kaplan Illinois Institute of Technology, Chicago, Illinois, USA T.H. Luo, D.J. Summers UMiss, University, Mississippi, USA
	Funding: This work was supported by the Office of Science, U.S. Department of Energy under DOE contract number DE-AC02-05CH11231, US Muon Accelerator Program and NSF MRI award: 0959000. Recent progress on the design and fabrication of the RFCC (RF and Coupling Coil) module for the international MICE (Muon Ionization Cooling Experiment) will be reported. The MICE ionization cooling channel has two RFCC modules; each having four 201-MHz normal conducting RF cavities surrounded by one superconducting coupling coil (solenoid) magnet. The magnet is designed to be cooled by 3 cryocoolers. Fabrication of the RF cavities is complete; preparation for the cavity electro-polishing, low power RF measurements and tuning are in progress at LBNL. Fabrication of the cold mass of the first coupling coil magnet has been completed in China and the cold mass arrived at LBNL in late 2011. Preparations for testing the cold mass are currently under way at Fermilab. Plans for the RFCC module assembly and integration are being developed and will be described.

Paper

Title

Page

Progress on a Cavity with Beryllium Walls for Muon Ionization Cooling Channel R&D

3356

D.L. Bowring, A.J. DeMello, A.R. Lambert, D. Li, S.P. Virostek, M.S. Zisman
LBNL, Berkeley, California, USA
D.M. Kaplan
Illinois Institute of Technology, Chicago, Illinois, USA
R.B. Palmer
BNL, Upton, Long Island, New York, USA

Funding: Work supported by the Director, Office of Science, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.
The Muon Accelerator Program (MAP) collaboration is working to develop an ionization cooling channel for future muon colliders. The ionization cooling channel requires the operation of high-gradient, normal-conducting RF cavities in solenoidal magnetic fields up to 5 T. However, experiments conducted at Fermilab's MuCool Test Area (MTA) show that increasing the solenoidal field strength reduces the maximum achievable cavity gradient. This gradient limit is characterized by an RF breakdown process that has caused significant damage to copper cavity interiors. The damage is likely caused by field-emitted electrons, focused by the solenoidal magnetic field onto small areas of the inner cavity surface. Local heating may then induce material fatigue and surface damage. Fabricating a cavity with beryllium walls would mitigate this damage due to beryllium's low density, low thermal expansion, and high electrical and thermal conductivity. This poster addresses the design and fabrication of a pillbox RF cavity with beryllium walls, in order to evaluate the performance of high-gradient cavities in strong magnetic fields.

THPPC034

Design and Analysis of the PXIE CW Radio-frequency Quadrupole (RFQ)

3359

S.P. Virostek, M.D. Hoff, A.R. Lambert, D. Li, J.W. Staples
LBNL, Berkeley, California, USA
G.V. Romanov
Fermilab, Batavia, USA
C. Zhang
IAP, Frankfurt am Main, Germany

Funding: This work is supported by the Office of Science, United States Department of Energy under DOE contract DE-AC02-05CH11231.
The Project X Injector Experiment (PXIE) will be a prototype front end of the Project X accelerator proposed by Fermilab. PXIE will consist of an H⁻ ion source, a low-energy beam transport (LEBT), a radio-frequency quadrupole (RFQ) accelerator, a medium-energy beam transport (MEBT) and a section of superconducting cryomodules that will accelerate the beam from 30 keV to 30 MeV. LBNL has developed an RFQ design for PXIE with fabrication scheduled to begin before the end of CY 2012. The chosen baseline design is a four-vane, 4.4 m long CW RFQ with a resonant frequency at 162.5 MHz (2.4 wavelengths long). The RFQ will provide bunching and acceleration of a nominal 5 mA H⁻ beam to 2.1 MeV. The relatively low wall power density results in wall power losses that are less than 100 kW. The beam dynamics design has been optimized to allow for more than 99% beam capture with exceptionally low longitudinal emittance. The RFQ mechanical design and the results of RF and thermal analyses are presented here.

THPPC035

Final Assembly and Testing of the MICE Superconducting Spectrometer Solenoids

3362

S.P. Virostek, M.A. Green, T.O. Niinikoski, H. Pan, S. Prestemon
LBNL, Berkeley, California, USA
R. Preece
STFC/RAL, Chilton, Didcot, Oxon, United Kingdom

Funding: This work was supported by the Office of Science, U.S. Department of Energy under DOE contract number DE-AC02-05CH11231.
The Muon Ionization Cooling Experiment (MICE) is an international effort to demonstrate the principle of ionization cooling in a segment of a realistic cooling channel using a muon beam. The experiment is sited at Rutherford Appleton Laboratory in England. A 4-tesla uniform field region at each end of the cooling channel will be provided by a pair of identical, 3-m long spectrometer solenoids. As the beam enters and exits the cooling channel, the emittance will be measured within both the upstream and downstream 400 mm diameter magnet bores. Each magnet consists of a three-coil spectrometer magnet group and a two-coil pair that matches the solenoid uniform field into the adjacent MICE cooling channel. An array of five two-stage cryocoolers and one single-stage cryocooler are used to maintain the temperature of the magnet cold mass, radiation shield and current leads. Previous testing revealed several operational and design issues related to heat leak and quench protection that have since been corrected. Details of the magnet design modifications and their final assembly as well as the results of quench training tests will be presented here.

THPPC049

Progress on the MICE 201 MHz RF Cavity at LBNL

3398

T.H. Luo, D.J. Summers
UMiss, University, Mississippi, USA
A.J. DeMello, D. Li, S.P. Virostek, M.S. Zisman
LBNL, Berkeley, California, USA

The international Muon Ionization Cooling Experiment (MICE) aims at demonstrating transverse cooling of muon beams by ionization. The ionization cooling channel of MICE requires eight 201-MHz normal conducting RF cavities to compensate for the longitudinal beam energy loss in the cooling channel. In this paper, we present recent progresses on MICE RF cavity at LBNL, which includes electro-polishing, intended to improve the cavity performance in the presence of strong external magnetic field; low power RF measurements on resonant frequency and Q value of each cavity with a pair of curved- beryllium windows to terminate the cavity irises. Multipacting simulations are conducted using SLAC’s ACE-3P code to study the effects in the cavity and coupler regions with the influence by external magnetic field.

THPPP064

Project X RFQ EM Design

3883

G.V. Romanov
Fermilab, Batavia, USA
M.D. Hoff, D. Li, J.W. Staples, S.P. Virostek
LBNL, Berkeley, California, USA

Project X is a proposed multi-MW proton facility at Fermi National Accelerator Laboratory (FNAL). The Project X front-end would consist of an H⁻ ion source, a low-energy beam transport (LEBT), a cw 162.5 MHz radio-frequency quadrupole (RFQ) accelerator, and a medium-energy beam transport (MEBT). Lawrence Berkeley National Laboratory (LBNL) and FNAL collaboration is currently developing the designs for various components in the Project X front end. This paper reports the detailed EM design of the cw 162.5 MHz RFQ that provides bunching of the 1-10 mA H⁻ beam with acceleration from 30 keV to 2.1 MeV.

THPPP092

Progress of the Front-End System Development for Project X at LBNL

3951

D. Li, M.D. Hoff, Q. Ji, A.R. Lambert, T. Schenkel, J.W. Staples, S.P. Virostek
LBNL, Berkeley, California, USA
S. Nagaitsev, L.R. Prost, G.V. Romanov, A.V. Shemyakin
Fermilab, Batavia, USA
C. Zhang
IAP, Frankfurt am Main, Germany

Funding: This work is supported by the Office of Science, United States Department of Energy under DOE contract DE-AC02-05CH11231.
A multi-MW proton facility, Project X has been proposed and is currently under development at Fermilab. Project X is a key accelerator complex for intensity frontier of future high energy physics programs in the US. In collaboration with Fermilab, LBNL takes the responsibility in the development and design studies of the front-end system for Project X. The front-end system would consist of H⁻ ion source(s), low-energy beam transport (LEBT), 162.5 MHz normal conducting CW Radio-Frequency-Quadrupole (RFQ) accelerator, medium-energy beam transport (MEBT), and beam chopper(s). In this paper, we will review and present recent progress of the front-end system studies, which will include the RFQ beam dynamics design, RF structure design, thermal and mechanical analyses and fabrication plan, LEBT simulation studies and concept for LEBT chopper.

THPPP093

Progress on MICE RFCC Module

3954

D. Li, D.L. Bowring, A.J. DeMello, S.A. Gourlay, M.A. Green, N. Li, T.O. Niinikoski, H. Pan, S. Prestemon, S.P. Virostek, M.S. Zisman
LBNL, Berkeley, California, USA
A.D. Bross, R.H. Carcagno, V. Kashikhin, C. Sylvester
Fermilab, Batavia, USA
Y. Cao, S. Sun, L. Wang, L. Yin
SINAP, Shanghai, People's Republic of China
A.B. Chen, B. Guo, L. Li, F.Y. Xu
ICST, Harbin, People's Republic of China
D.M. Kaplan
Illinois Institute of Technology, Chicago, Illinois, USA
T.H. Luo, D.J. Summers
UMiss, University, Mississippi, USA

Funding: This work was supported by the Office of Science, U.S. Department of Energy under DOE contract number DE-AC02-05CH11231, US Muon Accelerator Program and NSF MRI award: 0959000.
Recent progress on the design and fabrication of the RFCC (RF and Coupling Coil) module for the international MICE (Muon Ionization Cooling Experiment) will be reported. The MICE ionization cooling channel has two RFCC modules; each having four 201-MHz normal conducting RF cavities surrounded by one superconducting coupling coil (solenoid) magnet. The magnet is designed to be cooled by 3 cryocoolers. Fabrication of the RF cavities is complete; preparation for the cavity electro-polishing, low power RF measurements and tuning are in progress at LBNL. Fabrication of the cold mass of the first coupling coil magnet has been completed in China and the cold mass arrived at LBNL in late 2011. Preparations for testing the cold mass are currently under way at Fermilab. Plans for the RFCC module assembly and integration are being developed and will be described.