IPAC2017 - List of Keywords (flattop)

Paper	Title	Other Keywords	Page
MOPAB010	Anomaly Detection for Beam Loss Maps in the Large Hadron Collider	collimation, alignment, proton, collider	92
	G. Valentino University of Malta, Information and Communication Technology, Msida, Malta R. Bruce, S. Redaelli, R. Rossi, P. Theodoropoulos CERN, Geneva, Switzerland S. Jaster-Merz University of Hamburg, Hamburg, Germany
	In the LHC, beam loss maps are used to validate collimator settings for cleaning and machine protection. This is done by monitoring the loss distribution in the ring during infrequent controlled loss map campaigns, as well as in standard operation. Due to the complexity of the system, consisting of more than 50 collimators per beam, it is difficult to identify small changes in the collimation hierarchy, which may be due to setting errors or beam orbit drifts with such methods. A technique based on Principal Component Analysis and Local Outlier Factor is presented to detect anomalies in the loss maps and therefore provide an automatic check of the collimation hierarchy.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPAB010
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MOPAB154	Measurement of Proton Transverse Emittance in the Brookhaven AGS	emittance, dipole, injection, proton	494
	H. Huang, L. Ahrens, C.W. Dawson, C.E. Harper, C. Liu, F. Méot, M.G. Minty, V. Schoefer, S. Tepikian, K. Zeno BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. High luminosity and high polarization in RHIC require good control and measurement of emittance in its injector, the Brookhaven AGS. In the past, the AGS emittance has been measured by using an ion collecting IPM during the whole cycle. The beam profiles from this IPM are distorted by space charge forces at higher energy, which makes the emittance determination very hard. The effect has been measured with IPM measurement at different energies with RF off to mitigate the space charge effect. In addition, helical snake magnets and near integer vertical tune for polarized proton operation distort the lattice in the AGS and introduce large beta beating. For more precise measurements of the emittance, we need turn-by-turn (TBT) measurements near injection and beta function measurements at the IPM. The AGS has also been modeled to get the beta functions at the locations of IPM. A new type of electron collecting IPM has been installed and tested in the AGS with proton beam. The vertical beta functions at the IPM locations have been measured with a local corrector near the IPM. This paper summarizes our current understanding of AGS emittances and plans for the further improvements.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPAB154
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MOPIK034	The New High Field Injection Septum Magnet System for Main Ring of J-PARC	septum, injection, operation, power-supply	576
	T. Shibata, K. Ishii, H. Matsumoto, N. Matsumoto, T. Sugimoto KEK, Ibaraki, Japan K. Fan HUST, Wuhan, People's Republic of China
	We are improving the Main Ring (MR) for beam power of 750 kw which is the first goal of J-PARC. The repetition period of the fast extraction must be short to 1.3 second from the current period of 2.48 second for the improvement of the beam power. We exchanged a injection septum magnet which are located at the injection line from RCS to MR and its power supply in summer of 2016. It was necessary to exchange, because the previous injection septum system can not be operated with 1.3 second repetition. The development of the new injection septum magnet and its power supply in which the maximum repetition are 1Hz and the order od the leakage field are 10^-4 of the gap field were completed in 2016. In this presentation, we will report the final results of its performance, e.g. the magnetic fields and stability of the output current and field, and the beam performance after installation in MR with the new injection magnet.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPIK034
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MOPIK042	Beam-Based Kicker Waveform Measurements Using Long Bunches	kicker, emittance, injection, proton	599
	V. Forte, W. Bartmann, J.C.C.M. Borburgh, M.A. Fraser, L. Sermeus CERN, Geneva, Switzerland
	The increased bunch length demanded by the LHC Injectors Upgrade (LIU) project to mitigate emittance growth from space-charge on the PS injection plateau puts strong constraints on the rise-times of the recombination kickers in the transfer lines between the CERN Proton Synchrotron Booster (PSB) and the Proton Synchrotron (PS). A beam-based technique has been developed to validate the waveforms of the recombination kickers. In this paper high-resolution measurements are presented by extracting the intra-bunch deflection along bunches with lengths comparable to or longer than the rise-time of the kicker being probed. The methodology has been successfully applied to the three vertical recombination kickers named BT1. KFA10, BT4. KFA10 and BT2. KFA20, and benchmarked with direct measurements of the kicker field made using a magnetic field probe. This paper describes the beam-based technique, summarises the main characteristics of the measured waveforms, such as rise-time and flat-top ripple, and estimates their impact on beam brightness.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPIK042
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MOPIK043	Beam-Based Waveform Measurements of the CERN PS Injection Kicker	kicker, injection, impedance, timing	603
	V. Forte, W. Bartmann, J.C.C.M. Borburgh, L.M.C. Feliciano, A. Ferrero Colomo, M.A. Fraser, T. Kramer, L. Sermeus CERN, Geneva, Switzerland
	In the framework of the LHC Injectors Upgrade (LIU) project, a beam-based technique has been developed for measuring the waveform the CERN Proton Synchrotron (PS) horizontal injection kicker, named KFA45. The technique avoids the need for tedious magnetic measurements, especially when a spare magnet is presently unavailable and measuring the operational magnet with a magnetic field probe is complicated by integration reasons. In this paper, the technique and results of the waveform measurements are summarised. The results already provide additional information in terms of waveform characterisation for the validation of numerical simulations and are of great interest for the future LIU performance upgrade.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPIK043
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MOPIK063	Non-Linear Kickers Using Eddy Current Screens and Application to the ESRF	injection, kicker, sextupole, storage-ring	670
	S.M. White, M. Dubrulle, L. Farvacque, P. Henrissat, G. Le Bec, E. Plouviez, P. Raimondi, C. Richard ESRF, Grenoble, France
	The ESRF storage ring injection and accumulation is performed using standard 4-kickers bump and septum magnet. Sextupoles are located within the injection bump leading to significant bump non-closure during the ramp-up and ramp-down and optics distorsion for both stored and injected beam. Introducing non-linearities in the kickers allows for compensation of the perturbation from these sextupoles. We report on the feasibility of adding eddy current screens to a standard kicker magnet design to generate a non-linear field and its recent application to mitigate the injection perturbations at the ESRF.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPIK063
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TUPAB048	Long Beam Pulses With SLED Compression in DAΦNE LINAC	linac, gun, electron, klystron	1434
	P. Valente INFN-Roma, Roma, Italy M. Belli, B. Buonomo, R. Ceccarelli, A. Cecchinelli, R. Clementi, D.G.C. Di Giulio, L.G. Foggetta, G. Piermarini, L.A. Rossi, S. Strabioli, R. Zarlenga INFN/LNF, Frascati (Roma), Italy
	The DAΦNE LINAC is a ~60 m long, S-band (2856 MHz) linear accelerator, made up by four 45 MW klystrons with SLED compression, and by 15 travelling-wave, 2/3p, SLAC-type, 3 m long accelerating sections. It serves as injector of the DAΦNE e⁺ e⁻ collider, with 510 MeV, 10 ns long, electron and positron pulses, and the Beam-Test Facility extraction line, with variable beam energy and intensity and with pulses from 1.5 to 40 ns. A new pulsing system for the gun allows longer beam pulses, but the shape of the accelerating field in the sections due to the SLED compression has to be taken into account. We describe the tuning of the RF power, phase and delays in the pre-buncher, buncher and following accelerating sections, and the results of the tests performed in order to reach >200 ns 500 MeV electron pulses and the characterization of the quality of the beam in terms of energy spread, time distribution, etc.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB048
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TUPAB143	Dependence of LEReC Beam Energy Spread on Photocathode Laser Modulation	laser, electron, space-charge, impedance	1669
	S. Seletskiy, M. Blaskiewicz, A.V. Fedotov, D. Kayran, J. Kewisch, M.G. Minty, B. Sheehy, Z. Zhao BNL, Upton, Long Island, New York, USA B. Sheehy Sheehy Scientific Consulting, Wading River, New York, USA
	Present requirements to the photocathode DC gun of the low energy RHIC electron cooling (LEReC) project is to produce 100 ps long bunch of electrons with 130 pC charge. The laser pulse of required length will be produced with the stacking of multiple few picosecond long sub-pulses. Depending on the choice of the laser sub-pulse length and on the relative delay between these sub-pulses one can obtain laser pulse with various longitudinal intensity modulations. The longitudinal modulation of laser intensity creates longitudinal modulation of electron bunch charge. Such modulation is known to cause the growth of e-beam uncorrelated energy spread in photoinjectors - the effect we would like to avoid. In this paper we estimate growth of e-beam energy spread due to its initial density modulation and set requirements to the maximum allowable depth of longitudinal modulation of photocathode laser intensity.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB143
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TUPIK096	Data-Driven Controller Design for High Precision Pulsed Power Converters for Bumper Magnets of the PS Booster	controls, framework, booster, survey	1928
	A. Nicoletti, M. Martino CERN, Geneva, Switzerland
	A new data-driven approach using the frequency response function of a system is proposed for designing robust digital controllers for the injection bumper magnet (BSW) power supplies of the PS Booster. The powering of the BSW requires high precision 3.4 kA to 6.7 kA trapezoidal current pulses with 2 ms flat-top and 5 ms ramp-up and ramp-down time. The tracking error must remain within ± 50 parts-per-million (ppm) during the flat-top of the trapezoidal reference, and ± 500 ppm during the ramp-down. The BSW is powered with a four quadrant switch-mode power converter and the current through the magnet is controlled in closed-loop form with a 2-degree-of-freedom controller at a sampling rate of 10 kHz. A convex optimization algorithm is performed for obtaining the controller parameters. The effectiveness of the method is illustrated by designing the controller for a full-scale prototype of the BSW system at CERN, which is in the framework of the LHC Injector Upgrade (LIU) project.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK096
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WEPVA023	Performance of the PS Injection Kicker System Short Circuit Mode Upgrade for Operation with 2 GeV LIU Beams	kicker, injection, simulation, operation	3308
	T. Kramer, W. Bartmann, J.C.C.M. Borburgh, L. Ducimetière, L.M.C. Feliciano, A. Ferrero Colomo, B. Goddard, L. Sermeus CERN, Geneva, Switzerland
	In the framework of the LHC Injector Upgrade (LIU) project an upgrade of the existing PS proton injection kicker system for 2 GeV operation is in progress. The upgrade is based on the operation of the existing kicker system in short circuit mode. This paper briefly reviews the deployed modifications to the system to obtain the specified reduction of pulse reflections unavoidably induced by such a configuration. The implementation of improvements to the magnet entry box, transmission cables and the short circuit plug with integrated LC-filter are described as well as tests and measurements during the 2016/17 annual shutdown. The impact of the residual pulse shape structure on the beam performance for the reference LIU beam is quantified. The paper concludes with a performance analysis, a comparison of measurements vs. simulations and an outlook to the remaining modifications during the next long shut down.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA023
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WEPVA063	Development of a New Pulsed Power Supply with the SiC-MOSFET	power-supply, kicker, pulsed-power, operation	3412
	T. Takayanagi, K. Horino, J. Kamiya, M. Kinsho, T. Ueno, K. Yamamoto JAEA/J-PARC, Tokai-mura, Japan Y. Mushibe, A. Tokuchi Pulsed Power Japan Laboratory Ltd., Kusatsu-shi Shiga, Japan
	A new power supply has been developed using linear transformer driver (LTD) technology that adopts SiC-MOSFETs and capacitors without a thyratron switch or a pulse forming network (PFN) device. A new power supply was also designed by connecting the SiC-MOSFETs and the LTD modules in parallel-series. The output voltage and current were 40 kV and 4 kA, respectively with a pulse width of 1500 nsec at a repetition rate of 25 Hz. Furthermore, by adjusting the correction module, to an output voltage per stage of 1/1000, a resolution of the voltage correction of ±0.1 % could be achieved. It was possible to output the current with arbitrary timing by using a trigger input for each LTD module. As a result, fine adjustment of the output voltage waveform was possible within the order of nanoseconds. This new power supply with high voltage output, cur-rent output, and very fast pulse operation is one of the most important key technologies for a kicker system using SiC-MOSFETs. The design and preliminary test results of this prototype power supply are presented here.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA063
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WEPVA098	Measurements on a 12.5 kV Prototype Inductive Adder for the CLIC DR Extraction Kickers	kicker, extraction, damping, collider	3487
	J. Holma, M.J. Barnes CERN, Geneva, Switzerland
	The CLIC study is investigating the technical feasibility of an electron-positron collider with high luminosity and a nominal centre-of-mass energy of 3 TeV. The pre-damping rings and damping rings (DRs) will produce ultra-low emittance beam with high bunch charge. To avoid beam emittance increase, the DR kicker systems must provide extremely stable field pulses during injection and extraction of bunches. The DR extraction kicker system consists of a stripline kicker and two pulse modulators. The current specifications for the modulators call for pulses with 160 ns or 900 ns flattop duration of ±12.5 kV and 305 A, with ripple of not more than ±0.02 % (±2.5 V). An inductive adder is a very promising approach to meeting the specifications because analogue modulation methods can be applied to adjust the output waveform. Recently, the first full-scale, 20-layer, 12.5 kV prototype inductive adder has been assembled at CERN and testing has commenced. The goal is to tailor the output waveform of the prototype to the waveform required for the DR extraction stripline kicker. The results of the initial tests and measurements are presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA098
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WEPVA099	Influence of Conducting Serigraphy Upon Field Pulse Shape of the SPS Extraction Kicker Systems	kicker, extraction, impedance, high-voltage	3491
	A. Adraktas, M.J. Barnes, L. Ducimetière CERN, Geneva, Switzerland
	Fast pulsed magnets with ferrite yokes are used for beam extraction from the CERN SPS accelerator. These kickers are transmission line type magnets with a rectangular shaped aperture through which the beam circulates. Unless special precautions are taken, the beam impedance of the yoke can provoke significant induced heating, especially for high intensity beams. Previous upgrades of the SPS extraction kicker magnets have included silver fingers serigraphed on the surface of the ferrite facing the beam, to help shield the ferrite yoke from circulating beam. Beam based measurements of the extracted beam indicated that the serigraphy may influence the shape of the field pulse, causing it to increase slightly in magnitude during the flat-top. Hence theoretical studies have been carried out to determine whether the serigraphy influences the field pulse: these studies are reported in this paper.
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THPAB023	The Influence of Initial Current Density Distribution on the Emittance Reduction	emittance, cathode, gun, electron	3744
	H. Yamashita, T. Kii, K. Masuda, K. Nagasaki, T. Nogi, H. Ohgaki, K. Torgasin, H. Zen Kyoto University, Kyoto, Japan
	In this study, the influence of current density distribu-tion on the cathode surface on the beam emittance evolution was investigated. The emittance evolution with different beam profiles (flat-top, peak and hollow distribution) have been compared. The modification of the current profile was shown to affect the axial distance of the point of minimal emittance over wide range. The hollow profile allows extending the axial distance of the point of emittance minimum keeping its value extremely low. Further the parameters of a peak profile, which give the smallest emittance were determined. This work demonstrates the significance of initial current density distribution for the emittance evolution.
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THPAB077	Opal Simulations of the PSI Ring Cyclotron and a Design for a Higher Order Mode Flat Top Cavity	cavity, cyclotron, simulation, injection	3891
	N. Pogue LLNL, Livermore, California, USA A. Adelmann, L. Stingelin PSI, Villigen PSI, Switzerland
	Funding: The research leading to these results has received funding from the European Community's Seventh Framework Programme (FP7/ 2007-2013) under grant agreement n.°290605 (PSI-FELLOW/COFUND). The PSI cyclotron has been producing high power proton beam for 41 years. Over its lifetime it has been upgraded from producing 100 μA to 2.2 mA at 590 MeV. As the power reaches higher levels, it become more important to understand how the machine's beam dynamics will reach to new features of devices introduced. We present an OPAL (Object Oriented Parallel Accelerator Library) model of the cyclotron and compared it to the probe measurements from the machine. This model has good agreement with the measurements over the ~180 revolutions in the machine. Using this same model, a higher order mode flat top cavity was inserted into the machine to illustrate that its design and field structure allowed beam to be extracted. The HOM cavity design will also be presented. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
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THPIK027	Dynamic Behaviour of Fast-Pulsed Quadrupole Magnets for LINAC4 Transfer Line	quadrupole, linac, target, sextupole	4150
	S. Kasaei IPM, Tehran, Iran M.C.L. Buzio, L. Fiscarelli CERN, Geneva, Switzerland
	Linac4, recently built at CERN, is a linear normal conducting accelerator for negative hydrogen ions (H⁻). A new transfer line will link Linac4 to the Proton Synchrotron Booster. This transfer line includes 21 quadrupole magnets characterized by fast excitation cycles, which make accurate magnetic measurements challenging. This paper describes the method used for the measurement, which is a combination of techniques based on rotating and fixed search coils. We show how these instruments can be used in a complementary way to derive information on different aspects of the magnetic behaviour of these quadrupoles, such as the impact of hysteresis and dynamic eddy current effects.
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THPIK128	Switching Magnet for Heavy-Ion Beam Separation	power-supply, simulation, magnet-design, target	4403
	J.J. Hartzell, R.B. Agustsson, S.V. Kutsaev, A. Laurich, A.Y. Murokh, F.H. O'Shea, T.J. Villabona RadiaBeam, Santa Monica, California, USA G. Leyh LOD, Brisbane, USA E.A. Savin RadiaBeam Systems, Santa Monica, California, USA
	Funding: This work was supported by the United States Department of Energy SBIR Grant No. DE-SC0015124. We present a design for a complete switching magnet system capable of deflecting 8-25 MeV/u heavy-ion beams by 10 degrees. The system can produce flat-top pulses from 1 to 30 ms with rise and fall times of less than 0.5 ms at a duty cycle of 3-91% into a heavily inductive load. As determined by physics needs, the operational parameters of this magnet place it between fast rising kicker magnets with short duration and slow rising (or DC) resistive magnets which are optimized for efficiency and current-based power loss. This magnet must operate efficiently with over 91% duty factor and have a modestly fast rise time. The resulting design uses a resistive magnet scheme, to optimize the current-based losses, that is pulsed using a new circuit to control the applied voltage. The magnet has a laminated, iron dominated, H-shaped core. Directly-cooled copper pancake coils energize the magnet. The modulator employs a novel, proprietary, over-voltage topology to overcome the inherent inductance and achieve the fast rise and fall times, switching to a precision DC supply to efficiently maintain the flattop without requiring voltage in excess of ±3 kV.
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Paper

Title

Other Keywords

Page

MOPAB010

Anomaly Detection for Beam Loss Maps in the Large Hadron Collider

collimation, alignment, proton, collider

92

G. Valentino
University of Malta, Information and Communication Technology, Msida, Malta
R. Bruce, S. Redaelli, R. Rossi, P. Theodoropoulos
CERN, Geneva, Switzerland
S. Jaster-Merz
University of Hamburg, Hamburg, Germany

In the LHC, beam loss maps are used to validate collimator settings for cleaning and machine protection. This is done by monitoring the loss distribution in the ring during infrequent controlled loss map campaigns, as well as in standard operation. Due to the complexity of the system, consisting of more than 50 collimators per beam, it is difficult to identify small changes in the collimation hierarchy, which may be due to setting errors or beam orbit drifts with such methods. A technique based on Principal Component Analysis and Local Outlier Factor is presented to detect anomalies in the loss maps and therefore provide an automatic check of the collimation hierarchy.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPAB010

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MOPAB154

Measurement of Proton Transverse Emittance in the Brookhaven AGS

emittance, dipole, injection, proton

494

H. Huang, L. Ahrens, C.W. Dawson, C.E. Harper, C. Liu, F. Méot, M.G. Minty, V. Schoefer, S. Tepikian, K. Zeno
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
High luminosity and high polarization in RHIC require good control and measurement of emittance in its injector, the Brookhaven AGS. In the past, the AGS emittance has been measured by using an ion collecting IPM during the whole cycle. The beam profiles from this IPM are distorted by space charge forces at higher energy, which makes the emittance determination very hard. The effect has been measured with IPM measurement at different energies with RF off to mitigate the space charge effect. In addition, helical snake magnets and near integer vertical tune for polarized proton operation distort the lattice in the AGS and introduce large beta beating. For more precise measurements of the emittance, we need turn-by-turn (TBT) measurements near injection and beta function measurements at the IPM. The AGS has also been modeled to get the beta functions at the locations of IPM. A new type of electron collecting IPM has been installed and tested in the AGS with proton beam. The vertical beta functions at the IPM locations have been measured with a local corrector near the IPM. This paper summarizes our current understanding of AGS emittances and plans for the further improvements.

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MOPIK034

The New High Field Injection Septum Magnet System for Main Ring of J-PARC

septum, injection, operation, power-supply

576

T. Shibata, K. Ishii, H. Matsumoto, N. Matsumoto, T. Sugimoto
KEK, Ibaraki, Japan
K. Fan
HUST, Wuhan, People's Republic of China

We are improving the Main Ring (MR) for beam power of 750 kw which is the first goal of J-PARC. The repetition period of the fast extraction must be short to 1.3 second from the current period of 2.48 second for the improvement of the beam power. We exchanged a injection septum magnet which are located at the injection line from RCS to MR and its power supply in summer of 2016. It was necessary to exchange, because the previous injection septum system can not be operated with 1.3 second repetition. The development of the new injection septum magnet and its power supply in which the maximum repetition are 1Hz and the order od the leakage field are 10^-4 of the gap field were completed in 2016. In this presentation, we will report the final results of its performance, e.g. the magnetic fields and stability of the output current and field, and the beam performance after installation in MR with the new injection magnet.

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MOPIK042

Beam-Based Kicker Waveform Measurements Using Long Bunches

kicker, emittance, injection, proton

599

V. Forte, W. Bartmann, J.C.C.M. Borburgh, M.A. Fraser, L. Sermeus
CERN, Geneva, Switzerland

The increased bunch length demanded by the LHC Injectors Upgrade (LIU) project to mitigate emittance growth from space-charge on the PS injection plateau puts strong constraints on the rise-times of the recombination kickers in the transfer lines between the CERN Proton Synchrotron Booster (PSB) and the Proton Synchrotron (PS). A beam-based technique has been developed to validate the waveforms of the recombination kickers. In this paper high-resolution measurements are presented by extracting the intra-bunch deflection along bunches with lengths comparable to or longer than the rise-time of the kicker being probed. The methodology has been successfully applied to the three vertical recombination kickers named BT1. KFA10, BT4. KFA10 and BT2. KFA20, and benchmarked with direct measurements of the kicker field made using a magnetic field probe. This paper describes the beam-based technique, summarises the main characteristics of the measured waveforms, such as rise-time and flat-top ripple, and estimates their impact on beam brightness.

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MOPIK043

Beam-Based Waveform Measurements of the CERN PS Injection Kicker

kicker, injection, impedance, timing

603

V. Forte, W. Bartmann, J.C.C.M. Borburgh, L.M.C. Feliciano, A. Ferrero Colomo, M.A. Fraser, T. Kramer, L. Sermeus
CERN, Geneva, Switzerland

In the framework of the LHC Injectors Upgrade (LIU) project, a beam-based technique has been developed for measuring the waveform the CERN Proton Synchrotron (PS) horizontal injection kicker, named KFA45. The technique avoids the need for tedious magnetic measurements, especially when a spare magnet is presently unavailable and measuring the operational magnet with a magnetic field probe is complicated by integration reasons. In this paper, the technique and results of the waveform measurements are summarised. The results already provide additional information in terms of waveform characterisation for the validation of numerical simulations and are of great interest for the future LIU performance upgrade.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPIK043

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MOPIK063

Non-Linear Kickers Using Eddy Current Screens and Application to the ESRF

injection, kicker, sextupole, storage-ring

670

S.M. White, M. Dubrulle, L. Farvacque, P. Henrissat, G. Le Bec, E. Plouviez, P. Raimondi, C. Richard
ESRF, Grenoble, France

The ESRF storage ring injection and accumulation is performed using standard 4-kickers bump and septum magnet. Sextupoles are located within the injection bump leading to significant bump non-closure during the ramp-up and ramp-down and optics distorsion for both stored and injected beam. Introducing non-linearities in the kickers allows for compensation of the perturbation from these sextupoles. We report on the feasibility of adding eddy current screens to a standard kicker magnet design to generate a non-linear field and its recent application to mitigate the injection perturbations at the ESRF.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPIK063

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TUPAB048

Long Beam Pulses With SLED Compression in DAΦNE LINAC

linac, gun, electron, klystron

1434

P. Valente
INFN-Roma, Roma, Italy
M. Belli, B. Buonomo, R. Ceccarelli, A. Cecchinelli, R. Clementi, D.G.C. Di Giulio, L.G. Foggetta, G. Piermarini, L.A. Rossi, S. Strabioli, R. Zarlenga
INFN/LNF, Frascati (Roma), Italy

The DAΦNE LINAC is a ~60 m long, S-band (2856 MHz) linear accelerator, made up by four 45 MW klystrons with SLED compression, and by 15 travelling-wave, 2/3p, SLAC-type, 3 m long accelerating sections. It serves as injector of the DAΦNE e⁺ e⁻ collider, with 510 MeV, 10 ns long, electron and positron pulses, and the Beam-Test Facility extraction line, with variable beam energy and intensity and with pulses from 1.5 to 40 ns. A new pulsing system for the gun allows longer beam pulses, but the shape of the accelerating field in the sections due to the SLED compression has to be taken into account. We describe the tuning of the RF power, phase and delays in the pre-buncher, buncher and following accelerating sections, and the results of the tests performed in order to reach >200 ns 500 MeV electron pulses and the characterization of the quality of the beam in terms of energy spread, time distribution, etc.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB048

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TUPAB143

Dependence of LEReC Beam Energy Spread on Photocathode Laser Modulation

laser, electron, space-charge, impedance

1669

S. Seletskiy, M. Blaskiewicz, A.V. Fedotov, D. Kayran, J. Kewisch, M.G. Minty, B. Sheehy, Z. Zhao
BNL, Upton, Long Island, New York, USA
B. Sheehy
Sheehy Scientific Consulting, Wading River, New York, USA

Present requirements to the photocathode DC gun of the low energy RHIC electron cooling (LEReC) project is to produce 100 ps long bunch of electrons with 130 pC charge. The laser pulse of required length will be produced with the stacking of multiple few picosecond long sub-pulses. Depending on the choice of the laser sub-pulse length and on the relative delay between these sub-pulses one can obtain laser pulse with various longitudinal intensity modulations. The longitudinal modulation of laser intensity creates longitudinal modulation of electron bunch charge. Such modulation is known to cause the growth of e-beam uncorrelated energy spread in photoinjectors - the effect we would like to avoid. In this paper we estimate growth of e-beam energy spread due to its initial density modulation and set requirements to the maximum allowable depth of longitudinal modulation of photocathode laser intensity.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB143

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TUPIK096

Data-Driven Controller Design for High Precision Pulsed Power Converters for Bumper Magnets of the PS Booster

controls, framework, booster, survey

1928

A. Nicoletti, M. Martino
CERN, Geneva, Switzerland

A new data-driven approach using the frequency response function of a system is proposed for designing robust digital controllers for the injection bumper magnet (BSW) power supplies of the PS Booster. The powering of the BSW requires high precision 3.4 kA to 6.7 kA trapezoidal current pulses with 2 ms flat-top and 5 ms ramp-up and ramp-down time. The tracking error must remain within ± 50 parts-per-million (ppm) during the flat-top of the trapezoidal reference, and ± 500 ppm during the ramp-down. The BSW is powered with a four quadrant switch-mode power converter and the current through the magnet is controlled in closed-loop form with a 2-degree-of-freedom controller at a sampling rate of 10 kHz. A convex optimization algorithm is performed for obtaining the controller parameters. The effectiveness of the method is illustrated by designing the controller for a full-scale prototype of the BSW system at CERN, which is in the framework of the LHC Injector Upgrade (LIU) project.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK096

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WEPVA023

Performance of the PS Injection Kicker System Short Circuit Mode Upgrade for Operation with 2 GeV LIU Beams

kicker, injection, simulation, operation

3308

T. Kramer, W. Bartmann, J.C.C.M. Borburgh, L. Ducimetière, L.M.C. Feliciano, A. Ferrero Colomo, B. Goddard, L. Sermeus
CERN, Geneva, Switzerland

In the framework of the LHC Injector Upgrade (LIU) project an upgrade of the existing PS proton injection kicker system for 2 GeV operation is in progress. The upgrade is based on the operation of the existing kicker system in short circuit mode. This paper briefly reviews the deployed modifications to the system to obtain the specified reduction of pulse reflections unavoidably induced by such a configuration. The implementation of improvements to the magnet entry box, transmission cables and the short circuit plug with integrated LC-filter are described as well as tests and measurements during the 2016/17 annual shutdown. The impact of the residual pulse shape structure on the beam performance for the reference LIU beam is quantified. The paper concludes with a performance analysis, a comparison of measurements vs. simulations and an outlook to the remaining modifications during the next long shut down.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA023

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WEPVA063

Development of a New Pulsed Power Supply with the SiC-MOSFET

power-supply, kicker, pulsed-power, operation

3412

T. Takayanagi, K. Horino, J. Kamiya, M. Kinsho, T. Ueno, K. Yamamoto
JAEA/J-PARC, Tokai-mura, Japan
Y. Mushibe, A. Tokuchi
Pulsed Power Japan Laboratory Ltd., Kusatsu-shi Shiga, Japan

A new power supply has been developed using linear transformer driver (LTD) technology that adopts SiC-MOSFETs and capacitors without a thyratron switch or a pulse forming network (PFN) device. A new power supply was also designed by connecting the SiC-MOSFETs and the LTD modules in parallel-series. The output voltage and current were 40 kV and 4 kA, respectively with a pulse width of 1500 nsec at a repetition rate of 25 Hz. Furthermore, by adjusting the correction module, to an output voltage per stage of 1/1000, a resolution of the voltage correction of ±0.1 % could be achieved. It was possible to output the current with arbitrary timing by using a trigger input for each LTD module. As a result, fine adjustment of the output voltage waveform was possible within the order of nanoseconds. This new power supply with high voltage output, cur-rent output, and very fast pulse operation is one of the most important key technologies for a kicker system using SiC-MOSFETs. The design and preliminary test results of this prototype power supply are presented here.

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WEPVA098

Measurements on a 12.5 kV Prototype Inductive Adder for the CLIC DR Extraction Kickers

kicker, extraction, damping, collider

3487

J. Holma, M.J. Barnes
CERN, Geneva, Switzerland

The CLIC study is investigating the technical feasibility of an electron-positron collider with high luminosity and a nominal centre-of-mass energy of 3 TeV. The pre-damping rings and damping rings (DRs) will produce ultra-low emittance beam with high bunch charge. To avoid beam emittance increase, the DR kicker systems must provide extremely stable field pulses during injection and extraction of bunches. The DR extraction kicker system consists of a stripline kicker and two pulse modulators. The current specifications for the modulators call for pulses with 160 ns or 900 ns flattop duration of ±12.5 kV and 305 A, with ripple of not more than ±0.02 % (±2.5 V). An inductive adder is a very promising approach to meeting the specifications because analogue modulation methods can be applied to adjust the output waveform. Recently, the first full-scale, 20-layer, 12.5 kV prototype inductive adder has been assembled at CERN and testing has commenced. The goal is to tailor the output waveform of the prototype to the waveform required for the DR extraction stripline kicker. The results of the initial tests and measurements are presented.

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WEPVA099

Influence of Conducting Serigraphy Upon Field Pulse Shape of the SPS Extraction Kicker Systems

kicker, extraction, impedance, high-voltage

3491

A. Adraktas, M.J. Barnes, L. Ducimetière
CERN, Geneva, Switzerland

Fast pulsed magnets with ferrite yokes are used for beam extraction from the CERN SPS accelerator. These kickers are transmission line type magnets with a rectangular shaped aperture through which the beam circulates. Unless special precautions are taken, the beam impedance of the yoke can provoke significant induced heating, especially for high intensity beams. Previous upgrades of the SPS extraction kicker magnets have included silver fingers serigraphed on the surface of the ferrite facing the beam, to help shield the ferrite yoke from circulating beam. Beam based measurements of the extracted beam indicated that the serigraphy may influence the shape of the field pulse, causing it to increase slightly in magnitude during the flat-top. Hence theoretical studies have been carried out to determine whether the serigraphy influences the field pulse: these studies are reported in this paper.

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THPAB023

The Influence of Initial Current Density Distribution on the Emittance Reduction

emittance, cathode, gun, electron

3744

H. Yamashita, T. Kii, K. Masuda, K. Nagasaki, T. Nogi, H. Ohgaki, K. Torgasin, H. Zen
Kyoto University, Kyoto, Japan

In this study, the influence of current density distribu-tion on the cathode surface on the beam emittance evolution was investigated. The emittance evolution with different beam profiles (flat-top, peak and hollow distribution) have been compared. The modification of the current profile was shown to affect the axial distance of the point of minimal emittance over wide range. The hollow profile allows extending the axial distance of the point of emittance minimum keeping its value extremely low. Further the parameters of a peak profile, which give the smallest emittance were determined. This work demonstrates the significance of initial current density distribution for the emittance evolution.

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THPAB077

Opal Simulations of the PSI Ring Cyclotron and a Design for a Higher Order Mode Flat Top Cavity

cavity, cyclotron, simulation, injection

3891

N. Pogue
LLNL, Livermore, California, USA
A. Adelmann, L. Stingelin
PSI, Villigen PSI, Switzerland

Funding: The research leading to these results has received funding from the European Community's Seventh Framework Programme (FP7/ 2007-2013) under grant agreement n.°290605 (PSI-FELLOW/COFUND).
The PSI cyclotron has been producing high power proton beam for 41 years. Over its lifetime it has been upgraded from producing 100 μA to 2.2 mA at 590 MeV. As the power reaches higher levels, it become more important to understand how the machine's beam dynamics will reach to new features of devices introduced. We present an OPAL (Object Oriented Parallel Accelerator Library) model of the cyclotron and compared it to the probe measurements from the machine. This model has good agreement with the measurements over the ~180 revolutions in the machine. Using this same model, a higher order mode flat top cavity was inserted into the machine to illustrate that its design and field structure allowed beam to be extracted. The HOM cavity design will also be presented. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

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THPIK027

Dynamic Behaviour of Fast-Pulsed Quadrupole Magnets for LINAC4 Transfer Line

quadrupole, linac, target, sextupole

4150

S. Kasaei
IPM, Tehran, Iran
M.C.L. Buzio, L. Fiscarelli
CERN, Geneva, Switzerland

Linac4, recently built at CERN, is a linear normal conducting accelerator for negative hydrogen ions (H⁻). A new transfer line will link Linac4 to the Proton Synchrotron Booster. This transfer line includes 21 quadrupole magnets characterized by fast excitation cycles, which make accurate magnetic measurements challenging. This paper describes the method used for the measurement, which is a combination of techniques based on rotating and fixed search coils. We show how these instruments can be used in a complementary way to derive information on different aspects of the magnetic behaviour of these quadrupoles, such as the impact of hysteresis and dynamic eddy current effects.

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THPIK128

Switching Magnet for Heavy-Ion Beam Separation

power-supply, simulation, magnet-design, target

4403

J.J. Hartzell, R.B. Agustsson, S.V. Kutsaev, A. Laurich, A.Y. Murokh, F.H. O'Shea, T.J. Villabona
RadiaBeam, Santa Monica, California, USA
G. Leyh
LOD, Brisbane, USA
E.A. Savin
RadiaBeam Systems, Santa Monica, California, USA

Funding: This work was supported by the United States Department of Energy SBIR Grant No. DE-SC0015124.
We present a design for a complete switching magnet system capable of deflecting 8-25 MeV/u heavy-ion beams by 10 degrees. The system can produce flat-top pulses from 1 to 30 ms with rise and fall times of less than 0.5 ms at a duty cycle of 3-91% into a heavily inductive load. As determined by physics needs, the operational parameters of this magnet place it between fast rising kicker magnets with short duration and slow rising (or DC) resistive magnets which are optimized for efficiency and current-based power loss. This magnet must operate efficiently with over 91% duty factor and have a modestly fast rise time. The resulting design uses a resistive magnet scheme, to optimize the current-based losses, that is pulsed using a new circuit to control the applied voltage. The magnet has a laminated, iron dominated, H-shaped core. Directly-cooled copper pancake coils energize the magnet. The modulator employs a novel, proprietary, over-voltage topology to overcome the inherent inductance and achieve the fast rise and fall times, switching to a precision DC supply to efficiently maintain the flattop without requiring voltage in excess of ±3 kV.

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