IPAC2012 - List of Authors (Li, D.)

Paper	Title	Page
TUPPP059	Effects of Metal Mirrors Reflectivity and Aberrations on THz FEL Radiation Performance	1729
	P. Tan, T. Yu HUST, Wuhan, People's Republic of China M. Fan, Q. Fu, D. Li, B. Qin, Y.Q. Xiong, Y.B. Yibin Huazhong University of Science and Technology (HUST), Wuhan, People's Republic of China
	The primary design study of terahertz free-electron laser (FEL) is presented in this paper. The effects of optical cavity parameter, metal mirrors reflectivity and aberrations on the THz FEL radiation performance have been explored. The reflectivity characteristics of copper, silver and gold are tested in terahertz region. The effects of metal mirrors reflectivity and aberrations on the THz FEL radiation performance are studied by numerical simulation.

THPPC056	Development of 12kW RF Power Supply for CYCHU-10 Cyclotron	3416
	D. Li, T. Hu, J. Huang, K.F. Liu, B. Qin, J. Yang, L. Yang Huazhong University of Science and Technology (HUST), Wuhan, People's Republic of China
	One 12kW RF power supply has been developed for CYCHU-10, which is a 10 MeV cyclotron developed in Huazhong University of Science and Technology (HUST). A high performance DDS chip AD9859 is used to synthesize RF signal in this power supply, which is easy to change the output frequency. The centre frequency is 101MHz, and the frequency bandwidth is more than 1MHz. The RF power supply could operate in fine searching mode, coarse searching mode, tracking mode, and so on. It could search the resonant frequency of cavity with the frequency control loop. The final stage amplifier using a triode 3CW20,000H7 operates in grounded grid configuration, which is stable and reliable. The performance test using a 50Ω resistor load has finished, and major results are shown in this paper.

TUPPP070	Next Generation Light Source R&D and Design Studies at LBNL	1762
	J.N. Corlett, B. Austin, K.M. Baptiste, D.L. Bowring, J.M. Byrd, S. De Santis, P. Denes, R.J. Donahue, L.R. Doolittle, P. Emma, D. Filippetto, G. Huang, T. Koettig, S. Kwiatkowski, D. Li, T.P. Lou, H. Nishimura, H.A. Padmore, C. F. Papadopoulos, G.C. Pappas, G. Penn, M. Placidi, S. Prestemon, D. Prosnitz, J. Qiang, A. Ratti, M.W. Reinsch, D. Robin, F. Sannibale, D. Schlueter, R.W. Schoenlein, J.W. Staples, C. Steier, C. Sun, T. Vecchione, M. Venturini, W. Wan, R.P. Wells, R.B. Wilcox, J.S. Wurtele LBNL, Berkeley, California, USA
	Funding: Work supported by the Director, Office of Science, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. LBNL is developing design concepts for a multi-beamline soft x-ray FEL array powered by a superconducting linear accelerator, operating with a high bunch repetition rate of approximately one MHz. The cw superconducting linear accelerator is supplied by an injector based on a high-brightness, high-repetition-rate photocathode electron gun. Electron bunches are distributed from the linac to the array of independently configurable FEL beamlines with nominal bunch rates up to 100 kHz in each FEL, and with even pulse spacing. Individual FELs may be configured for different modes of operation, and each may produce high peak and average brightness x-rays with a flexible pulse format, and with pulse durations ranging from sub-femtoseconds to hundreds of femtoseconds. In this paper we describe conceptual design studies and optimizations. We describe recent developments in the design and performance parameters, and progress in R&D activities.

WEPPC031	Completed Assembly of the Daresbury International ERL Cryomodule and its Implementation on ALICE	2272
	P.A. McIntosh, M.A. Cordwell, P.A. Corlett, P. Davies, E. Frangleton, P. Goudket, K.J. Middleman, S.M. Pattalwar, A.E. Wheelhouse STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom S.A. Belomestnykh BNL, Upton, Long Island, New York, USA A. Büchner, F.G. Gabriel, P. Michel HZDR, Dresden, Germany J.N. Corlett, D. Li, S.M. Lidia LBNL, Berkeley, California, USA G.H. Hoffstaetter, M. Liepe, H. Padamsee, P. Quigley, J. Sears, V.D. Shemelin, V. Veshcherevich CLASSE, Ithaca, New York, USA T.J. Jones, J. Strachan STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom R.E. Laxdal TRIUMF, Canada's National Laboratory for Particle and Nuclear Physics, Vancouver, Canada D. Proch, J.K. Sekutowicz DESY, Hamburg, Germany T.I. Smith Stanford University, Stanford, California, USA
	The completion of an optimised SRF cryomodule for application on ERL accelerators has now culminated with the successful assembly of an integrated cryomodule, following an intensive 5 years of development evolution. The cryomodule, which incorporates 2 x 7-cell 1.3 GHz accelerating structures, 3 separate layers of magnetic shielding, fully adjustable & high power input couplers and fast piezo tuners, has been installed on the ALICE ERL facility at Daresbury Laboratory. It is intended that this will permit operational optimisation for maximised efficiency demonstration, through increased Qext adjustment whilst retaining both effective energy recovery and IR-FEL lasing. The collaborative design processes employed in completing this new cryomodule development are explained, along with the assembly and implementation procedures used to facilitate its successful installation on the ALICE ERL facility.

THPPC028	Kinetic Modeling of RF Breakdown in High-Pressure Gas-filled Cavities	3341
	D. Rose, C.H. Thoma Voss Scientific, Albuquerque, New Mexico, USA J.M. Byrd, D. Li LBNL, Berkeley, California, USA R.P. Johnson, M.L. Neubauer, R. Sah Muons, Inc, Batavia, USA A.V. Tollestrup, K. Yonehara Fermilab, Batavia, USA
	Funding: Supported in part by USDOE STTR Grant DE-FG02-08ER86352 Recent studies have shown that high gradients can be achieved quickly in high-pressure gas-filled cavities without the need for long conditioning times, because the dense gas can dramatically reduce dark currents and multipacting. In this project we use this high pressure technique to suppress effects of residual vacuum and geometry found in evacuated cavities to isolate and study the role of the metallic surfaces in RF cavity breakdown as a function of radiofrequency and surface preparation. A series of experiments at 805 MHz using hydrogen fill pressures up to 0.01 g/cm³ of H2 have demonstrated high electric field gradients and scaling with the DC Paschen law limit, up to ~30 MV/m, depending on the choice of electrode material. For higher field stresses, the breakdown characteristics deviate from the Paschen law scaling. Fully-kinetic 0D collisional particle-in-cell (PIC) simulations give breakdown characteristics in H2 and H2/SF6 mixtures in good agreement with the 805 MHz experimental results below this field stress threshold. The impact of these results on gas-filled RF accelerating cavity design will be discussed.

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.

THPPC040	Improved RF Design for an 805 MHz Pillbox Cavity for the US MuCool Program	3371
	Z. Li, C. Adolphsen, L. Ge SLAC, Menlo Park, California, USA D.L. Bowring, D. Li LBNL, Berkeley, California, USA
	Funding: Work supported by US DOE under contract number DE-AC02-05CH11231, and DE-AC02-76SF00515. Normal conducting RF cavities are required to operate at high gradient in the presence of strong magnetic field in muon ionization cooling channels for a Muon Collider. Experimental studies using an 805 MHz pillbox cavity at MTA of Fermilab has shown significant degradation in gradient performance and damage in the regions that are correlated with high RF fields in magnetic field up to 4 Tesla. These effects are believed to be related to the dark current and/or multipacting activities in the presence of external magnetic field. To improve the performance of the cavity, a new RF cavity with significantly lower surface field enhancement was designed, and will be built and tested in the near future. Numerical analyses of multipacting and dark current were performed using the 3D parallel code Track3P for both the original and new improved cavity profiles in order to gain more insight in understanding of the gradient issues under strong external magnetic field. In this paper, we will present the improved RF design and the dark current and multipacting analyses for the 805 MHz cavity.

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.

THPPP058	PXIE: Project X Injector Experiment	3874
	S. Nagaitsev, S.D. Holmes, R.D. Kephart, J.S. Kerby, V.A. Lebedev, C.S. Mishra, A.V. Shemyakin, N. Solyak, R.P. Stanek Fermilab, Batavia, USA D. Li LBNL, Berkeley, California, USA P.N. Ostroumov ANL, Argonne, USA
	A multi-MW proton facility, Project X has been proposed and is currently under development at Fermilab. As part of this development program, we are constructing a prototype of the front end of the Project X linac at Fermilab. The construction and successful operations of this facility will validate the concept for the Project X front end, thereby minimizing the primary technical risk element within the Project. The Project X Injector Experiment (PXIE) can be constructed over the period FY12-16 and will include an H⁻ ion source, a CW 2.1-MeV RFQ and two SC cryomodules providing up to 30 MeV energy gain at an average beam current of 1 mA. Successful operations of the facility will demonstrate the viability of novel front end technologies that will find applications beyond Project X in the longer term.

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

Effects of Metal Mirrors Reflectivity and Aberrations on THz FEL Radiation Performance

1729

P. Tan, T. Yu
HUST, Wuhan, People's Republic of China
M. Fan, Q. Fu, D. Li, B. Qin, Y.Q. Xiong, Y.B. Yibin
Huazhong University of Science and Technology (HUST), Wuhan, People's Republic of China

The primary design study of terahertz free-electron laser (FEL) is presented in this paper. The effects of optical cavity parameter, metal mirrors reflectivity and aberrations on the THz FEL radiation performance have been explored. The reflectivity characteristics of copper, silver and gold are tested in terahertz region. The effects of metal mirrors reflectivity and aberrations on the THz FEL radiation performance are studied by numerical simulation.

THPPC056

Development of 12kW RF Power Supply for CYCHU-10 Cyclotron

3416

D. Li, T. Hu, J. Huang, K.F. Liu, B. Qin, J. Yang, L. Yang
Huazhong University of Science and Technology (HUST), Wuhan, People's Republic of China

One 12kW RF power supply has been developed for CYCHU-10, which is a 10 MeV cyclotron developed in Huazhong University of Science and Technology (HUST). A high performance DDS chip AD9859 is used to synthesize RF signal in this power supply, which is easy to change the output frequency. The centre frequency is 101MHz, and the frequency bandwidth is more than 1MHz. The RF power supply could operate in fine searching mode, coarse searching mode, tracking mode, and so on. It could search the resonant frequency of cavity with the frequency control loop. The final stage amplifier using a triode 3CW20,000H7 operates in grounded grid configuration, which is stable and reliable. The performance test using a 50Ω resistor load has finished, and major results are shown in this paper.

TUPPP070

Next Generation Light Source R&D and Design Studies at LBNL

1762

J.N. Corlett, B. Austin, K.M. Baptiste, D.L. Bowring, J.M. Byrd, S. De Santis, P. Denes, R.J. Donahue, L.R. Doolittle, P. Emma, D. Filippetto, G. Huang, T. Koettig, S. Kwiatkowski, D. Li, T.P. Lou, H. Nishimura, H.A. Padmore, C. F. Papadopoulos, G.C. Pappas, G. Penn, M. Placidi, S. Prestemon, D. Prosnitz, J. Qiang, A. Ratti, M.W. Reinsch, D. Robin, F. Sannibale, D. Schlueter, R.W. Schoenlein, J.W. Staples, C. Steier, C. Sun, T. Vecchione, M. Venturini, W. Wan, R.P. Wells, R.B. Wilcox, J.S. Wurtele
LBNL, Berkeley, California, USA

Funding: Work supported by the Director, Office of Science, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.
LBNL is developing design concepts for a multi-beamline soft x-ray FEL array powered by a superconducting linear accelerator, operating with a high bunch repetition rate of approximately one MHz. The cw superconducting linear accelerator is supplied by an injector based on a high-brightness, high-repetition-rate photocathode electron gun. Electron bunches are distributed from the linac to the array of independently configurable FEL beamlines with nominal bunch rates up to 100 kHz in each FEL, and with even pulse spacing. Individual FELs may be configured for different modes of operation, and each may produce high peak and average brightness x-rays with a flexible pulse format, and with pulse durations ranging from sub-femtoseconds to hundreds of femtoseconds. In this paper we describe conceptual design studies and optimizations. We describe recent developments in the design and performance parameters, and progress in R&D activities.

WEPPC031

Completed Assembly of the Daresbury International ERL Cryomodule and its Implementation on ALICE

2272

P.A. McIntosh, M.A. Cordwell, P.A. Corlett, P. Davies, E. Frangleton, P. Goudket, K.J. Middleman, S.M. Pattalwar, A.E. Wheelhouse
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
S.A. Belomestnykh
BNL, Upton, Long Island, New York, USA
A. Büchner, F.G. Gabriel, P. Michel
HZDR, Dresden, Germany
J.N. Corlett, D. Li, S.M. Lidia
LBNL, Berkeley, California, USA
G.H. Hoffstaetter, M. Liepe, H. Padamsee, P. Quigley, J. Sears, V.D. Shemelin, V. Veshcherevich
CLASSE, Ithaca, New York, USA
T.J. Jones, J. Strachan
STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
R.E. Laxdal
TRIUMF, Canada's National Laboratory for Particle and Nuclear Physics, Vancouver, Canada
D. Proch, J.K. Sekutowicz
DESY, Hamburg, Germany
T.I. Smith
Stanford University, Stanford, California, USA

The completion of an optimised SRF cryomodule for application on ERL accelerators has now culminated with the successful assembly of an integrated cryomodule, following an intensive 5 years of development evolution. The cryomodule, which incorporates 2 x 7-cell 1.3 GHz accelerating structures, 3 separate layers of magnetic shielding, fully adjustable & high power input couplers and fast piezo tuners, has been installed on the ALICE ERL facility at Daresbury Laboratory. It is intended that this will permit operational optimisation for maximised efficiency demonstration, through increased Qext adjustment whilst retaining both effective energy recovery and IR-FEL lasing. The collaborative design processes employed in completing this new cryomodule development are explained, along with the assembly and implementation procedures used to facilitate its successful installation on the ALICE ERL facility.

THPPC028

Kinetic Modeling of RF Breakdown in High-Pressure Gas-filled Cavities

3341

D. Rose, C.H. Thoma
Voss Scientific, Albuquerque, New Mexico, USA
J.M. Byrd, D. Li
LBNL, Berkeley, California, USA
R.P. Johnson, M.L. Neubauer, R. Sah
Muons, Inc, Batavia, USA
A.V. Tollestrup, K. Yonehara
Fermilab, Batavia, USA

Funding: Supported in part by USDOE STTR Grant DE-FG02-08ER86352
Recent studies have shown that high gradients can be achieved quickly in high-pressure gas-filled cavities without the need for long conditioning times, because the dense gas can dramatically reduce dark currents and multipacting. In this project we use this high pressure technique to suppress effects of residual vacuum and geometry found in evacuated cavities to isolate and study the role of the metallic surfaces in RF cavity breakdown as a function of radiofrequency and surface preparation. A series of experiments at 805 MHz using hydrogen fill pressures up to 0.01 g/cm³ of H2 have demonstrated high electric field gradients and scaling with the DC Paschen law limit, up to ~30 MV/m, depending on the choice of electrode material. For higher field stresses, the breakdown characteristics deviate from the Paschen law scaling. Fully-kinetic 0D collisional particle-in-cell (PIC) simulations give breakdown characteristics in H2 and H2/SF6 mixtures in good agreement with the 805 MHz experimental results below this field stress threshold. The impact of these results on gas-filled RF accelerating cavity design will be discussed.

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.

THPPC040

Improved RF Design for an 805 MHz Pillbox Cavity for the US MuCool Program

3371

Z. Li, C. Adolphsen, L. Ge
SLAC, Menlo Park, California, USA
D.L. Bowring, D. Li
LBNL, Berkeley, California, USA

Funding: Work supported by US DOE under contract number DE-AC02-05CH11231, and DE-AC02-76SF00515.
Normal conducting RF cavities are required to operate at high gradient in the presence of strong magnetic field in muon ionization cooling channels for a Muon Collider. Experimental studies using an 805 MHz pillbox cavity at MTA of Fermilab has shown significant degradation in gradient performance and damage in the regions that are correlated with high RF fields in magnetic field up to 4 Tesla. These effects are believed to be related to the dark current and/or multipacting activities in the presence of external magnetic field. To improve the performance of the cavity, a new RF cavity with significantly lower surface field enhancement was designed, and will be built and tested in the near future. Numerical analyses of multipacting and dark current were performed using the 3D parallel code Track3P for both the original and new improved cavity profiles in order to gain more insight in understanding of the gradient issues under strong external magnetic field. In this paper, we will present the improved RF design and the dark current and multipacting analyses for the 805 MHz cavity.

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.

THPPP058

PXIE: Project X Injector Experiment

3874

S. Nagaitsev, S.D. Holmes, R.D. Kephart, J.S. Kerby, V.A. Lebedev, C.S. Mishra, A.V. Shemyakin, N. Solyak, R.P. Stanek
Fermilab, Batavia, USA
D. Li
LBNL, Berkeley, California, USA
P.N. Ostroumov
ANL, Argonne, USA

A multi-MW proton facility, Project X has been proposed and is currently under development at Fermilab. As part of this development program, we are constructing a prototype of the front end of the Project X linac at Fermilab. The construction and successful operations of this facility will validate the concept for the Project X front end, thereby minimizing the primary technical risk element within the Project. The Project X Injector Experiment (PXIE) can be constructed over the period FY12-16 and will include an H⁻ ion source, a CW 2.1-MeV RFQ and two SC cryomodules providing up to 30 MeV energy gain at an average beam current of 1 mA. Successful operations of the facility will demonstrate the viability of novel front end technologies that will find applications beyond Project X in the longer term.

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.