IPAC2018 - List of Authors (Rimmer, R.A.)

Paper	Title	Page
MOPMK015	Development of a Bunched-Beam Electron Cooler for the Jefferson Lab Electron-Ion Collider	382
	S.V. Benson, Y.S. Derbenev, D. Douglas, F.E. Hannon, A. Hutton, R. Li, R.A. Rimmer, Y. Roblin, C. Tennant, H. Wang, H. Zhang, Y. Zhang JLab, Newport News, Virginia, USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S.DOE Contract No. DE-AC05-06OR23177. Jefferson Lab is in the process of designing an electron-ion collider with unprecedented luminosity at a 65 GeV center-of-mass energy. This luminosity relies on ion cooling in both the booster and the storage ring of the accelerator complex. The cooling in the booster will use a conventional DC cooler similar to the one at COSY. The high-energy storage ring, operating at a momentum of up to 100 GeV/nucleon, requires novel use of bunched-beam cooling. We will present a new design for a Circulator Cooler Ring for bunched-beam electron cooling. This requires the generation and transport of very high-charge magnetized bunches, acceleration of the bunches in an energy recovery linac, and transfer of these bunches to a circulating ring that passes the bunches 11 times through the proton or ion beam inside cooling solenoids. This design requires the suppression of the effects of space charge and coherent synchrotron radiation using shielding and RF compensation.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMK015
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPMK017	Transient Beam Loading Due to the Bunch Train Gap and Its Compensation Experiments at BEPC-II and ALS	390
	H. Wang, R.A. Rimmer, S. Wang JLab, Newport News, Virginia, USA J.P. Dai, Q. Qin, J. Xing, J.H. Yue, Y. Zhang IHEP, Beijing, People's Republic of China D. Teytelman Dimtel, San Jose, USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. Non-uniform bunch fill patterns in storage rings, driven by the need to provide gaps for beam aborting and ion clearing cause a large beam loading change in the RF cavities. The induced turn-periodic transient in the cavity voltage modulates longitudinal beam properties along the train, such as synchronous position and bunch length. In the EIC design, due to the asymmetric bunch train structure between the electron and the ion beam, such modulation results in shifting collision point and leads to reduced luminosity. We have carried out the beam based experiments at BEPC-II and ALS using bunch-by-bunch diagnostic capabilities of the coupled-bunch feedback systems to study this transient effect. A modulated bunch filling pattern with higher charge density around the gap has been demonstrated to be effective in partially compensating this transient modulation. Details of the experimental setups and the data analysis will be presented to this conference.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMK017
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAL068	The Development of a Nw Fast Harmonic Kicker for the JLEIC Circulator Cooling Ring	1171
	G.-T. Park, F. Fors, J. Guo, R.A. Rimmer, H. Wang, S. Wang JLab, Newport News, Virginia, USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. After the first half-scale, 5 harmonic kicker cavity prototyping * for the JLEIC's CCR/ERL electron cooler and the beam dynamic simulation study of the 10-turn CCR *. The optimized circulation cooling turns has been changed to 11 and only 5 odd-harmonic modes from 86.6 MHz to 779.4 MHz plus a DC bias are needed for the harmonic RF kicker system. The new cavity design including the electromagnetic and thermal cooling optimization and its 11 turns beam bunch tracking simulation with the new numerology of RF deflecting voltages will be presented. Further design specifications for its RF harmonic drive and the broadband RF window, coupler and circulator component will be given for handling 5 kW of total RF power. Y, Huang, H. Wang et al., Physical Review Accelerators and Beams 19, 122001 (2016). ** Y. Huang, H. Wang et al., Physical Review Accelerators and Beams 19, 084201 (2016).
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL068
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAL069	Experimental Demonstration of Ion Beam Cooling with Pulsed Electron Beam	1174
	Y. Zhang, A. Hutton, K. Jordan, T. Powers, R.A. Rimmer, M. F. Spata, H. Wang, S. Wang, H. Zhang JLab, Newport News, Virginia, USA J. Li, X.M. Ma, L.J. Mao, M.T. Tang, J.C. Yang, X.D. Yang, H. Zhao, H.W. Zhao IMP/CAS, Lanzhou, People's Republic of China
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. Cooling ion beams at high energy is presently considered for several ion colliders, in order to achieve high luminosities by enabling a significant reduction of emittance of hadron beams. Electron beam at cooling channel in a few to tens MeV can be accelerated by a RF/SRF linac, and thus using bunched electrons to cool bunched ions. To study such cooling process, the DC electron gun of EC35 cooler at the storage ring CSRm, IMP was modified by pulsing the grid voltage. A 0.07-3.5 micro-second pulse length with a repetition frequency of less than 250 kHz and synchronized with the ion revolution frequency was obtained. The first experimental demonstration of cooling of a coasting and bunched ion beam by a pulsed electron beam was carried out. Data analysis indicates the bunch length shrinkage and the momentum spread reduction of bunched 12C+6 ion beam as evidence of cooling. A longitudinal grouping effect of the coasting ion beam by the electron pulses has also been observed. In this paper, we will present experimental results and comparison to the simulation modelling, particularly on the bunched electron cooling data after carefully analyzing the beam diagnostic signals. L.J. Mao et al., Experimental Demonstration of Electron Cooling with Bunched Electron Beam, TUP15, Proceedings of COOL2017, Bonn, Germany
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL069
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAL042	Injection Locked 1497 MHz Magnetron	3736
	M.L. Neubauer, A. Dudas, S.A. Kahn Muons, Inc, Illinois, USA R.A. Rimmer, H. Wang JLab, Newport News, Virginia, USA
	A novel injection-locked 1497 MHz 13 kW AM magnetron design is presented. The anode design to minimized eddy currents due to the changing magnetic field is presented. Thermal calculations of two design options are also presented. An extra degree of freedom in the anode construction is made possible by the fact that the magnetron is injection locked. This fact presents some additional design details that can be utilized in the cooling network for the magnetron anode.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL042
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAL134	Commissioning of the Prototype C75 Cavities in a CEBAF Cryomodule	3961
	M.A. Drury, G. Cheng, G. Ciovati, E. Daly, G.K. Davis, J. Guo, R.A. Legg, F. Marhauser, T. Powers, A.V. Reilly, R.A. Rimmer JLab, Newport News, Virginia, USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177 Prototype cavities have been built at Jefferson Lab to increase the energy of future refurbished CEBAF cryomodules to 75 MeV in the most cost efficient way. Three such cavities, named "C75", have been built from ingot Nb material of different purity and have been processed and tested. The two better performing cavities have been assembled into a "cavity pair" and installed in the latest refurbished original CEBAF cryomodule. The cryomodule was installed and commissioned in CEBAF. The results from the commissioning of the C75 cavities, compared with the original CEBAF cavities, are presented in this article. The vertical test performance of the C75 cavities was preserved in the cryomodule with one of the cavities achieving the performance specification of an accelerating gradient of 19 MV/m with a quality factor of ~8×10⁹ at 2.07 K. The performance in terms of microphonics and tuner operation was similar to that of original CEBAF cavities, as expected, and the high-order modes are properly damped. The quality factor of the two C75 cavities was the highest achieved in a CEBAF cryomodule, possibly due to the better magnetic flux expulsion of ingot Nb than standard fine-grain Nb.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL134
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAL144	952.6 MHz SRF Cavity Development for JLEIC	3982
	R.A. Rimmer, W.A. Clemens, F. Fors, J. Guo, F.E. Hannon, J. Henry, F. Marhauser, L. Turlington, H. Wang, S. Wang JLab, Newport News, Virginia, USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177 JLab is developing new SRF cavity designs at 952.6 MHz for the proposed Jefferson Lab Electron-Ion Collider (JLEIC). New cavities will be required for the ion ring, cooler ERL and booster and eventually for an upgrade of the electron ring to allow the highest possible bunch collision rate. The challenges include the need for high fundamental mode power couplers and strong HOM damping, with high HOM power capability. Initial focus is on the cooler ERL 5-cell cavity as this is a critical component for the strong, high energy, bunched-beam cooling concept. 1-cell and 5-cell Nb prototype cavities have been designed and fabricated. Details concerning the cavity fabrication and test results will be presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL144
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAL145	Magnetron R&D toward the Amplitude Modulation Control for SRF Accelerator	3986
	R.A. Rimmer, T. E. Plawski, H. Wang JLab, Newport News, Virginia, USA A. Dudas, S.A. Kahn, M.L. Neubauer Muons, Inc, Illinois, USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177 and SBIR grant DE-SC0013203 The scheme of using a high efficiency magnetron to drive a superconducting radio frequency (SRF) accelerator cavity needs not only the injection phase locking but also the amplitude modulation to compensate the cavity's microphomics caused cavity voltage change and the beam loading variation. To be able to do a fast and efficient modulation, the magnetron's magnetic field has to be trimmed by an external coil to compensate the frequency pushing effect due to the anode current change [1]. A low eddy current magnetron body has been designed and built [2]. This paper will present the analytical prediction, simulation and experimental results on the 2.45 GHz magnetron test stand with the modulation frequency up to 1 kHz. In addition, the progresses on the injection lock to a copper cavity, new 1497 MHz magnetron prototype, 13 kW high power magnetron test stand development and newly built low level RF (LLRF) controller for the amplitude modulation will be reported. [1] M. Neubauer et al, THPIK123, Proceedings of IPAC 2017, Copenhagen, Denmark [2] S. A. Kahn et al, THPIK121, Proceedings of IPAC 2017, Copenhagen, Denmark
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL145
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAL146	802 MHz ERL Cavity Design and Development	3990
	F. Marhauser, S. Castagnola, W.A. Clemens, J.G. Dail, P. Dhakal, F. Fors, J. Henry, R.A. Rimmer, L. Turlington, R.S. Williams JLab, Newport News, Virginia, USA R. Calaga, K.M. Dr. Schirm, E. Jensen CERN, Geneva, Switzerland
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177, and CERN Contract NR. KE3080/ATS In the framework of a collaboration between CERN and JLab, an SRF accelerating cavity for energy recovery linacs operating at 802 MHz was developed in the context of the CERN's Large Hadron electron Collider (LHeC) design study. A single-cell and a five-cell cavity from fine grain high RRR niobium were built at JLab to validate the basic RF design in vertical tests. Two copper single-cell cavities were produced in parallel for R&D purposes at CERN. The cavity design has since been adapted as baseline for the main linac cavities in the proposed Powerful Energy Recovery Linac Experiment facility (PERLE) at Orsay. Details concerning the cavity fabrication and test results for the Nb cavities are presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL146
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPMK105	PERLE - Lattice Design and Beam Dynamics Studies	4556
	S.A. Bogacz, D. Douglas, F.E. Hannon, A. Hutton, F. Marhauser, R.A. Rimmer, Y. Roblin, C. Tennant JLab, Newport News, Virginia, USA D. Angal-Kalinin, J.W. McKenzie, B.L. Militsyn, P.H. Williams Cockcroft Institute, Warrington, Cheshire, United Kingdom G. Arduini, O.S. Brüning, R. Calaga, K.M. Dr. Schirm, F. Gerigk, B.J. Holzer, E. Jensen, A. Milanese, E. Montesinos, D. Pellegrini, P.A. Thonet, A. Valloni CERN, Geneva, Switzerland S. Bousson, D. Longuevergne, G. Olivier, G. Olry IPN, Orsay, France I. Chaikovska, W. Kaabi, A. Stocchi, C. Vallerand LAL, Orsay, France B. Hounsell, M. Klein, U.K. Klein, P. Kostka, C.P. Welsch The University of Liverpool, Liverpool, United Kingdom E.B. Levichev, Yu.A. Pupkov BINP SB RAS, Novosibirsk, Russia
	Funding: Work has been authored by Jefferson Science Associates, LLC under Contract No. DE-AC05-06OR23177 with the U.S. Department of Energy. PERLE (Powerful ERL for Experiments) is a novel ERL test facility, initially proposed to validate choices for a 60 GeV ERL foreseen in the design of the LHeC and the FCC-eh. Its main thrust is to probe high current, CW, multi-pass operation with superconducting cavities at 802 MHz (and perhaps testing other frequencies of interest). With very high virtual beam power (~ 10 MW), PERLE offers an opportunity for controllable study of every beam dynamic effect of interest in the next generation of ERL design; becoming a ‘stepping stone' between present state-of-art 1 MW ERLs and future 100 MW scale applications. PERLE design features Flexible Momentum Compaction lattice architecture for six vertically stacked return arcs and a high-current, 6 MeV, photo-injector. With only one pair of 4 cavity cryomodules, 400 MeV beam energy can be reached in 3 re-circulation passes, with beam currents in excess of 15 mA. The beam is decelerated in 3 consecutive passes back to the injection energy, transferring virtually stored energy back to the RF. This unique facility will serve as a test-bed for high current ERL technologies, as well as a user facility in low energy electron and photon physics.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK105
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPML096	A Non-Invasive Magnetic Momentum Monitor Using a TE011 Cavity	4889
	J. Guo, J. Henry, M. Poelker, R.A. Rimmer, R. Suleiman, H. Wang JLab, Newport News, Virginia, USA
	Funding: Authored by Jefferson Science Associates, LLC with Laboratory Directed Research and Development funding, under U.S. DOE Contract No. DE-AC05-06OR23177. The Jefferson Lab Electron-Ion Collider (JLEIC) design relies on cooling of the ion beam with bunched electron beam. The bunched beam cooler complex consists of a high current magnetized electron source, an energy recovery linac, a circulating ring, and a pair of long solenoids where the cooling takes place. A non-invasive real time monitoring system is highly desired to quantify electron beam magnetization. The authors propose to use a passive copper RF cavity in TE011 mode as such a monitor. In this paper, we will show the mechanism and scaling law of this device, as well as the design and testing results of the prototype cavity.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML096
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

Development of a Bunched-Beam Electron Cooler for the Jefferson Lab Electron-Ion Collider

382

S.V. Benson, Y.S. Derbenev, D. Douglas, F.E. Hannon, A. Hutton, R. Li, R.A. Rimmer, Y. Roblin, C. Tennant, H. Wang, H. Zhang, Y. Zhang
JLab, Newport News, Virginia, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S.DOE Contract No. DE-AC05-06OR23177.
Jefferson Lab is in the process of designing an electron-ion collider with unprecedented luminosity at a 65 GeV center-of-mass energy. This luminosity relies on ion cooling in both the booster and the storage ring of the accelerator complex. The cooling in the booster will use a conventional DC cooler similar to the one at COSY. The high-energy storage ring, operating at a momentum of up to 100 GeV/nucleon, requires novel use of bunched-beam cooling. We will present a new design for a Circulator Cooler Ring for bunched-beam electron cooling. This requires the generation and transport of very high-charge magnetized bunches, acceleration of the bunches in an energy recovery linac, and transfer of these bunches to a circulating ring that passes the bunches 11 times through the proton or ion beam inside cooling solenoids. This design requires the suppression of the effects of space charge and coherent synchrotron radiation using shielding and RF compensation.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMK015

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPMK017

Transient Beam Loading Due to the Bunch Train Gap and Its Compensation Experiments at BEPC-II and ALS

390

H. Wang, R.A. Rimmer, S. Wang
JLab, Newport News, Virginia, USA
J.P. Dai, Q. Qin, J. Xing, J.H. Yue, Y. Zhang
IHEP, Beijing, People's Republic of China
D. Teytelman
Dimtel, San Jose, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
Non-uniform bunch fill patterns in storage rings, driven by the need to provide gaps for beam aborting and ion clearing cause a large beam loading change in the RF cavities. The induced turn-periodic transient in the cavity voltage modulates longitudinal beam properties along the train, such as synchronous position and bunch length. In the EIC design, due to the asymmetric bunch train structure between the electron and the ion beam, such modulation results in shifting collision point and leads to reduced luminosity. We have carried out the beam based experiments at BEPC-II and ALS using bunch-by-bunch diagnostic capabilities of the coupled-bunch feedback systems to study this transient effect. A modulated bunch filling pattern with higher charge density around the gap has been demonstrated to be effective in partially compensating this transient modulation. Details of the experimental setups and the data analysis will be presented to this conference.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMK017

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAL068

The Development of a Nw Fast Harmonic Kicker for the JLEIC Circulator Cooling Ring

1171

G.-T. Park, F. Fors, J. Guo, R.A. Rimmer, H. Wang, S. Wang
JLab, Newport News, Virginia, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
After the first half-scale, 5 harmonic kicker cavity prototyping * for the JLEIC's CCR/ERL electron cooler and the beam dynamic simulation study of the 10-turn CCR **. The optimized circulation cooling turns has been changed to 11 and only 5 odd-harmonic modes from 86.6 MHz to 779.4 MHz plus a DC bias are needed for the harmonic RF kicker system. The new cavity design including the electromagnetic and thermal cooling optimization and its 11 turns beam bunch tracking simulation with the new numerology of RF deflecting voltages will be presented. Further design specifications for its RF harmonic drive and the broadband RF window, coupler and circulator component will be given for handling 5 kW of total RF power.
* Y, Huang, H. Wang et al., Physical Review Accelerators and Beams 19, 122001 (2016).
** Y. Huang, H. Wang et al., Physical Review Accelerators and Beams 19, 084201 (2016).

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL068

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAL069

Experimental Demonstration of Ion Beam Cooling with Pulsed Electron Beam

1174

Y. Zhang, A. Hutton, K. Jordan, T. Powers, R.A. Rimmer, M. F. Spata, H. Wang, S. Wang, H. Zhang
JLab, Newport News, Virginia, USA
J. Li, X.M. Ma, L.J. Mao, M.T. Tang, J.C. Yang, X.D. Yang, H. Zhao, H.W. Zhao
IMP/CAS, Lanzhou, People's Republic of China

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
Cooling ion beams at high energy is presently considered for several ion colliders, in order to achieve high luminosities by enabling a significant reduction of emittance of hadron beams. Electron beam at cooling channel in a few to tens MeV can be accelerated by a RF/SRF linac, and thus using bunched electrons to cool bunched ions. To study such cooling process, the DC electron gun of EC35 cooler at the storage ring CSRm, IMP was modified by pulsing the grid voltage. A 0.07-3.5 micro-second pulse length with a repetition frequency of less than 250 kHz and synchronized with the ion revolution frequency was obtained. The first experimental demonstration of cooling of a coasting and bunched ion beam by a pulsed electron beam was carried out. Data analysis indicates the bunch length shrinkage and the momentum spread reduction of bunched 12C+6 ion beam as evidence of cooling. A longitudinal grouping effect of the coasting ion beam by the electron pulses has also been observed*. In this paper, we will present experimental results and comparison to the simulation modelling, particularly on the bunched electron cooling data after carefully analyzing the beam diagnostic signals.
* L.J. Mao et al., Experimental Demonstration of Electron Cooling with Bunched Electron Beam, TUP15, Proceedings of COOL2017, Bonn, Germany

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL069

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAL042

Injection Locked 1497 MHz Magnetron

3736

M.L. Neubauer, A. Dudas, S.A. Kahn
Muons, Inc, Illinois, USA
R.A. Rimmer, H. Wang
JLab, Newport News, Virginia, USA

A novel injection-locked 1497 MHz 13 kW AM magnetron design is presented. The anode design to minimized eddy currents due to the changing magnetic field is presented. Thermal calculations of two design options are also presented. An extra degree of freedom in the anode construction is made possible by the fact that the magnetron is injection locked. This fact presents some additional design details that can be utilized in the cooling network for the magnetron anode.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL042

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAL134

Commissioning of the Prototype C75 Cavities in a CEBAF Cryomodule

3961

M.A. Drury, G. Cheng, G. Ciovati, E. Daly, G.K. Davis, J. Guo, R.A. Legg, F. Marhauser, T. Powers, A.V. Reilly, R.A. Rimmer
JLab, Newport News, Virginia, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177
Prototype cavities have been built at Jefferson Lab to increase the energy of future refurbished CEBAF cryomodules to 75 MeV in the most cost efficient way. Three such cavities, named "C75", have been built from ingot Nb material of different purity and have been processed and tested. The two better performing cavities have been assembled into a "cavity pair" and installed in the latest refurbished original CEBAF cryomodule. The cryomodule was installed and commissioned in CEBAF. The results from the commissioning of the C75 cavities, compared with the original CEBAF cavities, are presented in this article. The vertical test performance of the C75 cavities was preserved in the cryomodule with one of the cavities achieving the performance specification of an accelerating gradient of 19 MV/m with a quality factor of ~8×10⁹ at 2.07 K. The performance in terms of microphonics and tuner operation was similar to that of original CEBAF cavities, as expected, and the high-order modes are properly damped. The quality factor of the two C75 cavities was the highest achieved in a CEBAF cryomodule, possibly due to the better magnetic flux expulsion of ingot Nb than standard fine-grain Nb.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL134

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAL144

952.6 MHz SRF Cavity Development for JLEIC

3982

R.A. Rimmer, W.A. Clemens, F. Fors, J. Guo, F.E. Hannon, J. Henry, F. Marhauser, L. Turlington, H. Wang, S. Wang
JLab, Newport News, Virginia, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177
JLab is developing new SRF cavity designs at 952.6 MHz for the proposed Jefferson Lab Electron-Ion Collider (JLEIC). New cavities will be required for the ion ring, cooler ERL and booster and eventually for an upgrade of the electron ring to allow the highest possible bunch collision rate. The challenges include the need for high fundamental mode power couplers and strong HOM damping, with high HOM power capability. Initial focus is on the cooler ERL 5-cell cavity as this is a critical component for the strong, high energy, bunched-beam cooling concept. 1-cell and 5-cell Nb prototype cavities have been designed and fabricated. Details concerning the cavity fabrication and test results will be presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL144

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAL145

Magnetron R&D toward the Amplitude Modulation Control for SRF Accelerator

3986

R.A. Rimmer, T. E. Plawski, H. Wang
JLab, Newport News, Virginia, USA
A. Dudas, S.A. Kahn, M.L. Neubauer
Muons, Inc, Illinois, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177 and SBIR grant DE-SC0013203
The scheme of using a high efficiency magnetron to drive a superconducting radio frequency (SRF) accelerator cavity needs not only the injection phase locking but also the amplitude modulation to compensate the cavity's microphomics caused cavity voltage change and the beam loading variation. To be able to do a fast and efficient modulation, the magnetron's magnetic field has to be trimmed by an external coil to compensate the frequency pushing effect due to the anode current change [1]. A low eddy current magnetron body has been designed and built [2]. This paper will present the analytical prediction, simulation and experimental results on the 2.45 GHz magnetron test stand with the modulation frequency up to 1 kHz. In addition, the progresses on the injection lock to a copper cavity, new 1497 MHz magnetron prototype, 13 kW high power magnetron test stand development and newly built low level RF (LLRF) controller for the amplitude modulation will be reported.
[1] M. Neubauer et al, THPIK123, Proceedings of IPAC 2017, Copenhagen, Denmark
[2] S. A. Kahn et al, THPIK121, Proceedings of IPAC 2017, Copenhagen, Denmark

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL145

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAL146

802 MHz ERL Cavity Design and Development

3990

F. Marhauser, S. Castagnola, W.A. Clemens, J.G. Dail, P. Dhakal, F. Fors, J. Henry, R.A. Rimmer, L. Turlington, R.S. Williams
JLab, Newport News, Virginia, USA
R. Calaga, K.M. Dr. Schirm, E. Jensen
CERN, Geneva, Switzerland

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177, and CERN Contract NR. KE3080/ATS
In the framework of a collaboration between CERN and JLab, an SRF accelerating cavity for energy recovery linacs operating at 802 MHz was developed in the context of the CERN's Large Hadron electron Collider (LHeC) design study. A single-cell and a five-cell cavity from fine grain high RRR niobium were built at JLab to validate the basic RF design in vertical tests. Two copper single-cell cavities were produced in parallel for R&D purposes at CERN. The cavity design has since been adapted as baseline for the main linac cavities in the proposed Powerful Energy Recovery Linac Experiment facility (PERLE) at Orsay. Details concerning the cavity fabrication and test results for the Nb cavities are presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL146

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPMK105

PERLE - Lattice Design and Beam Dynamics Studies

4556

S.A. Bogacz, D. Douglas, F.E. Hannon, A. Hutton, F. Marhauser, R.A. Rimmer, Y. Roblin, C. Tennant
JLab, Newport News, Virginia, USA
D. Angal-Kalinin, J.W. McKenzie, B.L. Militsyn, P.H. Williams
Cockcroft Institute, Warrington, Cheshire, United Kingdom
G. Arduini, O.S. Brüning, R. Calaga, K.M. Dr. Schirm, F. Gerigk, B.J. Holzer, E. Jensen, A. Milanese, E. Montesinos, D. Pellegrini, P.A. Thonet, A. Valloni
CERN, Geneva, Switzerland
S. Bousson, D. Longuevergne, G. Olivier, G. Olry
IPN, Orsay, France
I. Chaikovska, W. Kaabi, A. Stocchi, C. Vallerand
LAL, Orsay, France
B. Hounsell, M. Klein, U.K. Klein, P. Kostka, C.P. Welsch
The University of Liverpool, Liverpool, United Kingdom
E.B. Levichev, Yu.A. Pupkov
BINP SB RAS, Novosibirsk, Russia

Funding: Work has been authored by Jefferson Science Associates, LLC under Contract No. DE-AC05-06OR23177 with the U.S. Department of Energy.
PERLE (Powerful ERL for Experiments) is a novel ERL test facility, initially proposed to validate choices for a 60 GeV ERL foreseen in the design of the LHeC and the FCC-eh. Its main thrust is to probe high current, CW, multi-pass operation with superconducting cavities at 802 MHz (and perhaps testing other frequencies of interest). With very high virtual beam power (~ 10 MW), PERLE offers an opportunity for controllable study of every beam dynamic effect of interest in the next generation of ERL design; becoming a ‘stepping stone' between present state-of-art 1 MW ERLs and future 100 MW scale applications. PERLE design features Flexible Momentum Compaction lattice architecture for six vertically stacked return arcs and a high-current, 6 MeV, photo-injector. With only one pair of 4 cavity cryomodules, 400 MeV beam energy can be reached in 3 re-circulation passes, with beam currents in excess of 15 mA. The beam is decelerated in 3 consecutive passes back to the injection energy, transferring virtually stored energy back to the RF. This unique facility will serve as a test-bed for high current ERL technologies, as well as a user facility in low energy electron and photon physics.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK105

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPML096

A Non-Invasive Magnetic Momentum Monitor Using a TE011 Cavity

4889

J. Guo, J. Henry, M. Poelker, R.A. Rimmer, R. Suleiman, H. Wang
JLab, Newport News, Virginia, USA

Funding: Authored by Jefferson Science Associates, LLC with Laboratory Directed Research and Development funding, under U.S. DOE Contract No. DE-AC05-06OR23177.
The Jefferson Lab Electron-Ion Collider (JLEIC) design relies on cooling of the ion beam with bunched electron beam. The bunched beam cooler complex consists of a high current magnetized electron source, an energy recovery linac, a circulating ring, and a pair of long solenoids where the cooling takes place. A non-invasive real time monitoring system is highly desired to quantify electron beam magnetization. The authors propose to use a passive copper RF cavity in TE011 mode as such a monitor. In this paper, we will show the mechanism and scaling law of this device, as well as the design and testing results of the prototype cavity.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML096

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)