IPAC2016 - List of Keywords (recirculation)

Paper	Title	Other Keywords	Page
MOPMY001	Beam Dynamics Analysis for the Ultra-fast Kicker in Circular Cooler Ring of JLEIC	kicker, electron, emittance, cavity	510
	Y.L. Huang IMP/CAS, Lanzhou, People's Republic of China 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. An ultra-fast kicker system consist of four quarter wavelength resonator based deflecting cavities was developed that simultaneously resonates at 10 subharmonic modes of the 476.3MHz bunch repetition frequency, thus every 10th bunch in the bunch train will experience a transverse kick while all the other bunches are undisturbed. This fast kicker is developed for the Energy Recovery Linac (ERL) based electron Circular Cooler Ring (CCR) in the proposed Jefferson Lab Electron Ion Collider (JLEIC, previously MEIC). The electron bunches can be reused 10-30 turns thus the beam current in the ERL can be reduced to 1/10 - 1/30 (150mA - 50mA) of the cooling bunch current (1.5A). In this paper, several methods to synthesis such a kicker waveform will be discussed with the comparison of beam dynamics tracking in Elegant.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMY001
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TUPOR025	Beam Break-up Measurements at the Recirculating Electron Accelerator S-DALINAC	linac, HOM, experiment, cavity	1714
	T. Kürzeder, M. Arnold, L.E. Jürgensen, J. Pforr, N. Pietralla TU Darmstadt, Darmstadt, Germany F. Hug IKP, Mainz, Germany
	Funding: Supported by the German Federal Ministry for Education and Research (BMBF) under Grant No. 05K13RDA Beam break-up (BBU) instability is an important limitation to the current which can be accelerated in a superconducting linac. In particular recirculating machines and Energy Recovery Linacs have to deal with that problem. Therefore, it is important to find strategies for increasing the threshold currents of these machines. The superconducting accelerator S-DALINAC at the Technische Universität Darmstadt provides electron beams in c.w. for nuclear physics experiments since 1991. It consists of a 10 MeV injector and a 40 MeV main linac where two and eight 20-cell elliptical 3-GHz cavities are operated in a liquid helium bath at 2 K. Using two recirculation beam lines the main accelerator can be used up to 3 times. Operational experiences have shown that the design-beam current of 20 μA could not be reached. One reason is the occurrence of BBU. We will report on measurements of the threshold current at various energy settings of the S-DALINAC. The results of a first test to increase the BBU limit by using skew quadrupole magnets in the first recirculation beam line will be presented.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOR025
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TUPOR026	Final Design and Status of the Third Recirculation for the S-DALINAC*	dipole, linac, electron, operation	1717
	M. Arnold, T. Kürzeder, N. Pietralla TU Darmstadt, Darmstadt, Germany F. Hug IKP, Mainz, Germany
	Funding: *Work supported by DFG through CRC 634 and RTG 2128 Since 1991 the twice-recirculating superconducting accelerator S-DALINAC is providing electron beams for nuclear physics experiments. Due to a reduced quality factor of its cavities in comparison to their design values it was not possible to operate the accelerator with its maximum design energy of 130 MeV in cw mode. To provide electron beams of this energy in the future it was decided to add one recirculation beam line in order to use the main linac four times, operating the cavities on decreased accelerating gradients. The necessary modifications consist of several different aspects: A new beamline needs to be installed and other pre-existing beam line sections have to be modified for matching new boundary conditions. These new conditions are mainly a result of beam dynamics simulations and of the design of a new separation dipole magnet, which will bend the different beams energy-dependent in the various recirculation beam lines. We will present the implemented design and give a status report on the project.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOR026
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TUPOW038	Measurement and Control of Beam Losses Under High Average-current Operation of the Compact ERL at KEK	radiation, operation, beam-losses, optics	1839
	S. Sakanaka, K. Haga, Y. Honda, H. Matsumura, T. Miyajima, T. Nogami, T. Obina, H. Sagehashi, M. Shimada, M. Yamamoto KEK, Ibaraki, Japan
	The compact ERL (cERL)* is a superconducting accelerator aimed at demonstrating excellent ERL technologies for the future light source. The cERL comprises a 5 MeV injector, a main linac, and a recirculation loop. In the cERL, production and transportation of low-emittance and high average-current beams (tentative goals: 1 mm-mrad and 10 mA) is primarily important. At this moment (in December 2015), beam currents of up to 80 uA (CW) have successfully been transported through the recirculation loop at a beam energy of 20 MeV. Before such high-current operations, we carefully tuned up the machine so that beam losses became very small. The beam losses were watched using fast beam-loss detectors and radiation monitors while absolute losses were estimated from measured radiation levels on the roof of the shield. After careful beam-optics corrections and elimination of beam halos / tails at low-energy section, we achieved the beam losses of at most a few nA level at several locations along the loop, and those below 1 nA elsewhere in the loop. We will report these results together with the result of higher-current operation which is planned early in 2016. * S. Sakanaka et al., IPAC'15, TUBC1; T. Obina et al., to be presented at IPAC'16.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOW038
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WEPOR020	Beam Loss Estimation by Measurement of Secondarily Produced Photons under High Average-current Operations of Compact ERL in KEK	operation, detector, neutron, electron	2711
	H. Matsumura, K. Haga, K. Hozumi, T. Miura, S. Nagaguro, T. Obina, T. Oyama, S. Sakanaka, A. Toyoda KEK, Ibaraki, Japan N. Yoshihara Tokyo Nuclear Service Co. Ltd., Ibaraki, Japan
	To increase the beam current in the Compact Energy Recovery Linac (cERL) at the High Energy Accelerator Research Organization (KEK), the beam loss must be reduced to less than 0.01% during the transportation of 20 MeV electrons in order to suppress the radiation dose outside the accelerator room. Beam loss locations were successfully identified using the gold activation method, and the beam loss rate was estimated by com-paring the measured dose rate with the simulated dose rate on the roof of the cERL room. Beam operation with beam current of 0.90 mA was achieved with a beam loss rate of less than 0.01%.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOR020
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THPMB004	Improving Energy Spread and Stability of a Recirculating Few-turn Linac	linac, electron, synchrotron, experiment	3222
	F. Hug IKP, Mainz, Germany M. Arnold, T. Kürzeder, N. Pietralla TU Darmstadt, Darmstadt, Germany R.G. Eichhorn Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Funding: Supported by the DFG through CRC 634, RTG 2128 and PRISMA cluster of excellence A non-isochronous recirculation scheme which helps cancelling out errors coming from the RF-jitters in a recirculating linac will be presented. Non-isochronous recirculation is the common operation mode for synchrotrons or microtrons. In such a scheme the recirculation arcs provide a non-zero longitudinal dispersion, while the particle bunches are accelerated at a certain phase off-crest with respect to the maximum of the accelerating field. In few-turn linacs and microtrons such beam dynamics can be used to reduce the energy spread. To do so the longitudinal phase advance needs to be set to a half-integer number of oscillations in phase space. Then errors from linac RF-systems cancel out and the energy spread remains closely to the value at injection. In addition to the improved energy spread the beam stability of few-turn recirculators can be increased as well using such a system. We will present operational experience with the non-isochronous recirculation system of the twice recirculating superconducting accelerator S-DALINAC operated at TU Darmstadt including beam-dynamics calculations and measurements of the energy spread.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMB004
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Paper

Title

Other Keywords

Page

MOPMY001

Beam Dynamics Analysis for the Ultra-fast Kicker in Circular Cooler Ring of JLEIC

kicker, electron, emittance, cavity

510

Y.L. Huang
IMP/CAS, Lanzhou, People's Republic of China
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.
An ultra-fast kicker system consist of four quarter wavelength resonator based deflecting cavities was developed that simultaneously resonates at 10 subharmonic modes of the 476.3MHz bunch repetition frequency, thus every 10th bunch in the bunch train will experience a transverse kick while all the other bunches are undisturbed. This fast kicker is developed for the Energy Recovery Linac (ERL) based electron Circular Cooler Ring (CCR) in the proposed Jefferson Lab Electron Ion Collider (JLEIC, previously MEIC). The electron bunches can be reused 10-30 turns thus the beam current in the ERL can be reduced to 1/10 - 1/30 (150mA - 50mA) of the cooling bunch current (1.5A). In this paper, several methods to synthesis such a kicker waveform will be discussed with the comparison of beam dynamics tracking in Elegant.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMY001

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

TUPOR025

Beam Break-up Measurements at the Recirculating Electron Accelerator S-DALINAC

linac, HOM, experiment, cavity

1714

T. Kürzeder, M. Arnold, L.E. Jürgensen, J. Pforr, N. Pietralla
TU Darmstadt, Darmstadt, Germany
F. Hug
IKP, Mainz, Germany

Funding: Supported by the German Federal Ministry for Education and Research (BMBF) under Grant No. 05K13RDA
Beam break-up (BBU) instability is an important limitation to the current which can be accelerated in a superconducting linac. In particular recirculating machines and Energy Recovery Linacs have to deal with that problem. Therefore, it is important to find strategies for increasing the threshold currents of these machines. The superconducting accelerator S-DALINAC at the Technische Universität Darmstadt provides electron beams in c.w. for nuclear physics experiments since 1991. It consists of a 10 MeV injector and a 40 MeV main linac where two and eight 20-cell elliptical 3-GHz cavities are operated in a liquid helium bath at 2 K. Using two recirculation beam lines the main accelerator can be used up to 3 times. Operational experiences have shown that the design-beam current of 20 μA could not be reached. One reason is the occurrence of BBU. We will report on measurements of the threshold current at various energy settings of the S-DALINAC. The results of a first test to increase the BBU limit by using skew quadrupole magnets in the first recirculation beam line will be presented.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOR025

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TUPOR026

Final Design and Status of the Third Recirculation for the S-DALINAC*

dipole, linac, electron, operation

1717

M. Arnold, T. Kürzeder, N. Pietralla
TU Darmstadt, Darmstadt, Germany
F. Hug
IKP, Mainz, Germany

Funding: *Work supported by DFG through CRC 634 and RTG 2128
Since 1991 the twice-recirculating superconducting accelerator S-DALINAC is providing electron beams for nuclear physics experiments. Due to a reduced quality factor of its cavities in comparison to their design values it was not possible to operate the accelerator with its maximum design energy of 130 MeV in cw mode. To provide electron beams of this energy in the future it was decided to add one recirculation beam line in order to use the main linac four times, operating the cavities on decreased accelerating gradients. The necessary modifications consist of several different aspects: A new beamline needs to be installed and other pre-existing beam line sections have to be modified for matching new boundary conditions. These new conditions are mainly a result of beam dynamics simulations and of the design of a new separation dipole magnet, which will bend the different beams energy-dependent in the various recirculation beam lines. We will present the implemented design and give a status report on the project.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOR026

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TUPOW038

Measurement and Control of Beam Losses Under High Average-current Operation of the Compact ERL at KEK

radiation, operation, beam-losses, optics

1839

S. Sakanaka, K. Haga, Y. Honda, H. Matsumura, T. Miyajima, T. Nogami, T. Obina, H. Sagehashi, M. Shimada, M. Yamamoto
KEK, Ibaraki, Japan

The compact ERL (cERL)* is a superconducting accelerator aimed at demonstrating excellent ERL technologies for the future light source. The cERL comprises a 5 MeV injector, a main linac, and a recirculation loop. In the cERL, production and transportation of low-emittance and high average-current beams (tentative goals: 1 mm-mrad and 10 mA) is primarily important. At this moment (in December 2015), beam currents of up to 80 uA (CW) have successfully been transported through the recirculation loop at a beam energy of 20 MeV. Before such high-current operations, we carefully tuned up the machine so that beam losses became very small. The beam losses were watched using fast beam-loss detectors and radiation monitors while absolute losses were estimated from measured radiation levels on the roof of the shield. After careful beam-optics corrections and elimination of beam halos / tails at low-energy section, we achieved the beam losses of at most a few nA level at several locations along the loop, and those below 1 nA elsewhere in the loop. We will report these results together with the result of higher-current operation which is planned early in 2016.
* S. Sakanaka et al., IPAC'15, TUBC1; T. Obina et al., to be presented at IPAC'16.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOW038

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WEPOR020

Beam Loss Estimation by Measurement of Secondarily Produced Photons under High Average-current Operations of Compact ERL in KEK

operation, detector, neutron, electron

2711

H. Matsumura, K. Haga, K. Hozumi, T. Miura, S. Nagaguro, T. Obina, T. Oyama, S. Sakanaka, A. Toyoda
KEK, Ibaraki, Japan
N. Yoshihara
Tokyo Nuclear Service Co. Ltd., Ibaraki, Japan

To increase the beam current in the Compact Energy Recovery Linac (cERL) at the High Energy Accelerator Research Organization (KEK), the beam loss must be reduced to less than 0.01% during the transportation of 20 MeV electrons in order to suppress the radiation dose outside the accelerator room. Beam loss locations were successfully identified using the gold activation method, and the beam loss rate was estimated by com-paring the measured dose rate with the simulated dose rate on the roof of the cERL room. Beam operation with beam current of 0.90 mA was achieved with a beam loss rate of less than 0.01%.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOR020

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

THPMB004

Improving Energy Spread and Stability of a Recirculating Few-turn Linac

linac, electron, synchrotron, experiment

3222

F. Hug
IKP, Mainz, Germany
M. Arnold, T. Kürzeder, N. Pietralla
TU Darmstadt, Darmstadt, Germany
R.G. Eichhorn
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Funding: Supported by the DFG through CRC 634, RTG 2128 and PRISMA cluster of excellence
A non-isochronous recirculation scheme which helps cancelling out errors coming from the RF-jitters in a recirculating linac will be presented. Non-isochronous recirculation is the common operation mode for synchrotrons or microtrons. In such a scheme the recirculation arcs provide a non-zero longitudinal dispersion, while the particle bunches are accelerated at a certain phase off-crest with respect to the maximum of the accelerating field. In few-turn linacs and microtrons such beam dynamics can be used to reduce the energy spread. To do so the longitudinal phase advance needs to be set to a half-integer number of oscillations in phase space. Then errors from linac RF-systems cancel out and the energy spread remains closely to the value at injection. In addition to the improved energy spread the beam stability of few-turn recirculators can be increased as well using such a system. We will present operational experience with the non-isochronous recirculation system of the twice recirculating superconducting accelerator S-DALINAC operated at TU Darmstadt including beam-dynamics calculations and measurements of the energy spread.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMB004

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