IPAC2018 - Table of Session: WEPAK (MC6 Poster Session)

Paper	Title	Page
WEPAK001	Intense Neutrino Source Front End Beam Diagnostics System R&D	2077
	K. Yonehara, M.D. Balcazar, A. Moretti, A.V. Tollestrup, A.C. Watts, R.M. Zwaska Fermilab, Batavia, Illinois, USA M.A. Cummings, A. Dudas, R.P. Johnson, G.M. Kazakevich, M.L. Neubauer Muons, Inc, Illinois, USA
	Funding: Work supported by Fermilab Research Alliance, LLC under Contract No. DE-AC02-07CH11359 and DOE STTR Grant, No. DE-SC0013795. We overview the front end beam diagnostic system R&D to prepare operation of a multi-MW proton beam for intensity frontier Neutrino experiments. One of critical issues is shorter life time of a detector with higher beam intensity due to radiation damage. We show a possible improvement of the existing ion chamber based detector, and a study of a conceptually new radiation-robust detector which is based on a gas-filled RF resonator.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAK001
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WEPAK003	Effect of Model Errors on the Closed Orbit Correction at the SIS18 Synchrotron of GSI	2080
SUSPL057	use link to see paper's listing under its alternate paper code
	S.H. Mirza, P. Forck, H. Klingbeil, R. Singhpresenter GSI, Darmstadt, Germany H. Klingbeil TEMF, TU Darmstadt, Darmstadt, Germany
	Funding: Deutscher Akademischer Austauschdienst under contract No. 91605207 A fast closed orbit feedback system (bandwidth in the order of 1 kHz) is under development at the GSI SIS18 synchrotron for the orbit correction from injection to extraction including the acceleration ramp. The static process model, represented as the orbit response matrix (ORM), is subjected to the systematic optics changes during ramp e.g. beta function and phase advance variations at the locations of BPMs and steerers. In addition to these systematic variations, model mismatches may arise from dipole and quadrupole magnet errors, space charge dependent tune shift as well as BPM and steerer calibration errors. In this contribution, the effects of these model errors on the closed orbit correction are investigated which is necessary for the robust stability analysis of the feedback controller. For the robustness tests, the traditional SVD-based matrix pseudo-inversion is compared to a Fourier-based analysis. The results are achieved by detailed simulations in MADX.
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WEPAK004	Beam Instrumentation for CRYRING@ESR	2084
	A. Reiter, C. Andre, H. Bräuning, C. Dorn, P. Forck, R. Haseitl, T. Hoffmann, W. Kaufmann, N. Kotovski, P. Kowina, K. Lang, R. Lonsing, P.B. Miedzik, T. Milosic, A. Petit, H. Reeg, C. Schmidt, M. Schwickert, T. Sieber, R. Singh, G. Vorobjev, B. Walasek-Höhne, M. Witthaus GSI, Darmstadt, Germany
	We present the beam instrumentation of CRYRING@ESR, a low-energy experiment facility at the GSI Helmholtz-Centre for heavy ion research. The 1.44 Tm synchrotron and storage ring, formerly hosted at the Manne Siegbahn laboratory in Stockholm, Sweden, was modified in its configuration and installed behind the existing ESR, the experimental storage ring. As the first machine within the ongoing FAIR project, the facility for antiproton and ion research, it is built on the future timing system and frameworks for data supply and acquisition. Throughout the past year CRYRING was commissioned including its electron cooler with hydrogen beams from the local linear accelerator. Storage, acceleration and cooling have been demonstrated. The contribution provides an overview of the beam instrumentation. The design of the detector systems and their current performance are presented. Emphasis is given to beam position monitors, detectors for intensity measurements, and the ionization profile monitors.
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WEPAK005	A Cryogenic Current Comparators (CCC) Customized for FAIR-Project	2088
SUSPF098	use link to see paper's listing under its alternate paper code
	J. Golm, R. Neubert, F. Schmidl, P. Seidel FSU Jena, Jena, Germany J. Golm, T. Stöhlker, V. Tympel HIJ, Jena, Germany D.M. Haider, F. Kurian, M. Schwickert, T. Sieber, T. Stöhlker GSI, Darmstadt, Germany R. Neubert Thuringia Observatory Tautenburg, Tautenburg, Germany M. Schmelz, R. Stolz IPHT, Jena, Germany T. Stöhlker IOQ, Jena, Germany V. Zakosarenko Supracon AG, Jena, Germany
	The principle of non-destructive measurement of ion beams by detection of the azimuthal magnetic field, using low temperature Superconducting Quantum Interference Device (SQUID) sensors, has been established at GSI already in the mid 90's. After more recent developments at Jena, GSI and CERN, a CCC was installed in the CERN Antiproton Decelerator (AD) and is operated there routinely as the first stand-alone CCC system. For the Facility for Antiproton and Ion Research (FAIR) a new version of the CCC with eXtended Dimensions (CCC-XD) - especially with a larger inner diameter and adapted parameters - was constructed and first lab tests have already been performed. In parallel, a concept for a dedicated UHV beamline cryostat has been worked out. The CCC-XD system - together with the new cryostat - will be ready for testing in the CRYRING at GSI before the end of 2018. In this contribution, experimental results for the resolution, frequency range, slew rate and pulse-signal obtained by electrical laboratory measurements with the CCC-XD are presented.
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WEPAK006	Bunch Shape Measurements at the GSI CW-Linac Prototype	2091
	T. Sieber, W.A. Barth, P. Forck, V. Gettmann, M. Heilmann, H. Reeg, A. Reiter, S. Yaramyshev GSI, Darmstadt, Germany F.D. Dziuba, T. Kürzeder, M. Miski-Oglu HIM, Mainz, Germany A. Feschenko, S.A. Gavrilov RAS/INR, Moscow, Russia
	The existing GSI accelerator will become the injector for FAIR. To preserve and enhance the current experimental program at UNILAC, a new Linac is under development, which shall run in parallel to the FAIR injector, providing cw-beams of ions at energies from 3.5 - 7.3 MeV/u. For this cw-Linac a superconducting prototype cavity has been developed and was first operated with beam in summer 2017. The resonator is a cross-bar H-structure (CH) of 0.7 m length, with a resonant frequency of 216.8 MHz. It has been installed behind the GSI High Charge State Injector (HLI), which provided 10⁸ MHz bunches of 1.4 MeV/u Ar⁶⁺/9+/11+ ions at a duty cycle of 25 %. Due to the frequency jump and small longitudinal acceptance of the CH, proper matching of the HLI beam to the prototype was required. The bunch properties of the injected beam as well as the effect of different phase- and amplitude-settings of the cavity were measured in detail with a bunch shape monitor (BSM) fabricated at INR, Moscow, while the mean energy was analyzed by time of flight method. In this contribution, the bunch shape measurements are described and the capabilities of the used BSM measurement principle are discussed.
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WEPAK007	Slow Extraction Spill Characterization From Micro to Milli-Second Scale	2095
	R. Singh, P. Boutachkov, P. Forck, S. Sorge, H. Welker GSI, Darmstadt, Germany
	This contribution deals with the topic of slow extraction spill quality characterization based on the measurements performed at GSI SIS-18. The sensitivity of the spill to power supply ripples are studied by introducing external ripples. An estimate of sources of inherent power supply ripples along with ripple magnitude are thus obtained. Spill characterization in time and frequency domain are discussed and exemplified by a typical spill and the differences from an ideal or Poisson spill. An appropriate spill characterization aims to provide a suitable abstraction for communication about the spill quality requirements between accelerator operations and users.
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WEPAK008	Reconstructing Space-Charge Distorted IPM Profiles with Machine Learning Algorithms	2099
	D.M. Vilsmeier, M. Sapinski, R. Singhpresenter GSI, Darmstadt, Germany J.W. Storey CERN, Geneva, Switzerland
	Measurements of undistorted transverse profiles via Ionization Profile Monitors (IPMs) may pose a great challenge for high brightness or high energy beams due to interaction of ionized electrons or ions with the electromagnetic field of the beam. This contribution presents application of various machine learning algorithms to the problem of reconstructing the actual beam profile from measured profiles that are distorted by beam space-charge interaction. (Generalized) linear regression, artificial neural network and support vector machine algorithms are trained with simulation data, obtained from the Virtual-IPM simulation tool, in order to learn the relation between distorted profiles and original beam dimension. The performance of different algorithms is assessed and the obtained results are very promising for testing with simulation data.
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WEPAK009	Applications of the Interferometric Beam Size Monitor at BESSY II	2103
	M. Koopmans, P. Goslawski, J.G. Hwang, A. Jankowiak, M. Ries, A. Schälicke, G. Schiwietz HZB, Berlin, Germany
	For the upgrade project of the BESSY~II storage ring to BESSY~VSR * an interferometric beam size monitor was designed and set up. Since this system uses visible light it can be upgraded efficiently to provide bunch resolved measurements. These are required for machine commissioning, development and to ensure long term quality and stability of user operation of BESSY~VSR. Various applications of the system are outlined and measurements are presented. * A. Jankowiak et al., eds., BESSY VSR Technical Design Study, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Germany, June 2015. DOI: 10.5442/R0001
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WEPAK010	Simulations and Measurements of the BPM Non Linearity and Kicker Timing Influence on the Tune Shift With Amplitude (TSWA) Measurement at BESSY II	2107
	F. Kramer, P. Goslawski, J.G. Hwang, A. Jankowiak, P. Kuske, M. Ruprecht, A. Schälicke HZB, Berlin, Germany
	The Tune Shift With Amplitude (TSWA) does not only determine the position of the stable fix points for the Transverse Resonant Island Buckets (TRIBs) but also represents a global observable for the nonlinear optics in general. For theoretical investigations of the TRIBs a reliable nonlinear optics of the machine is required and thus all measurable global observables for the nonlinear optics are of great interest. The measurement of the TSWA for the BESSY II standard optics was performed using an injection kicker to excite high amplitude betatron oscillations and then extract the amplitude dependant frequency from the synchrotron radiation damped oscillation with a Hilbert transformation. With TRIBs optics the injection kicker was not able to sufficienty excite the beam. The impact and correctability of the BPM nonlinearity at the reached amplitudes and the reason for the failure of the excitation method for our TRIBs optics shall be looked onto in this paper.
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WEPAK011	Development of the Electron-Beam Diagnostics for the Future BESSY-VSR Storage Ring	2110
	G. Schiwietz, J.G. Hwang, M. Koopmans, M. Ries, A. Schälicke HZB, Berlin, Germany
	This contribution focusses on the different types of new or improved electron-beam monitors at BESSY II for bunch resolved measurements under future BESSY-VSR conditions. A new diagnostics platform, involving three different dipole beam lines will be built for different di-pole-related optical and THz methods. Our main concepts for robust future monitors for bunch length, beam size and position are presented in the following.
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WEPAK012	Developing Kalman Filter Based Detuning Control with a Digital SRF CW Cavity Simulator	2114
	A. Ushakov, P. Echevarria, A. Neumann HZB, Berlin, Germany
	Funding: Work supported by German Bundesministerium für Bildung und Forschung, Land Berlin, and grants of the Helmholtz Association Continuous wave operated superconducting cavities experiencing small net beam loading and thus operate potentially at narrow bandwidth require precise detuning control to reach the high stability requirements for RF fields within facilities as FEL or ERL based photon sources. Especially microphonics compensation down to sub-hertz detuning regime besides improving stability reduces the risk of rise of Lorentz force detuning driven ponderomotive instabilities. Usually the complex and second order nature of the mechanical to RF detuning transfer functions of cavity and cavity-tuner system require for more advanced control schemes. In this paper we will show the application of a Kalman filter based detuning estimator algorithm first introduced during IPAC2017 [1] to the SRF cavity simulator developed at Helmholtz Zentrum Berlin [2]. Results using the algorithm in observer mode to detuning compensation attempts in closed loop mode are presented. * A. Ushakov, P. Echevarria, A. Neumann, Proc. of IPAC 2017, Copenhagen, Denmark
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WEPAK013	SRF Cavity Simulator for LLRF Algorithms Debugging	2118
	P. Echevarria, J. Knobloch, A. Neumann, A. Ushakovpresenter HZB, Berlin, Germany E. Aldekoa, J. Jugo University of the Basque Country, Faculty of Science and Technology, Bilbao, Spain
	Funding: Work supported by German Bundesministerium für Bildung und Forschung, Land Berlin, and grants of Helmholtz Association The availability of niobium superconducting cavities, ei-ther due to a lack of a real cavity or due to the time needed for the experiment set up (vacuum, cryogenics, cabling, etc.), is limited, and thus it can block or delay the develop-ment of new algorithms such as low level RF control. Hardware-in-the-loop simulations, where an actual cavity is replaced by an electronics system, can help to solve this issue. In this paper we present a Cavity Simulator imple-mented in a National Instruments PXI equipped with an FPGA module. This module operates with one intermedi-ate frequency input which is IQ-demodulated and fed to the electrical cavity's model, where the transmitted and re-flected voltages are calculated and IQ-modulated to gener-ate two intermediate frequency outputs. Some more ad-vanced features such as mechanical vibration modes driven by Lorentz-force detuning or external microphonics have also been implemented. This Cavity Simulator is planned to be connected to an mTCA chassis to close the loop with a LLRF control system.
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WEPAK014	A New Pulse Magnet Control System in the KEK Electron Positron LINAC	2121
	Y. Enomoto, K. Furukawa, T. Natsui, M. Satoh KEK, Ibaraki, Japan H.S. Saotome Kanto Information Service (KIS), Accelerator Group, Ibaraki, Japan
	In 2017, sixty-four pules magnets were installed in the KEK e⁺/e⁻ LINAC for simultaneous injection to four different rings. Since each ring requires different injection energy, magnetic field in the LINAC has to be changed shot by shot (every 20 ms) according to the destination of the beam. To realize such operation, a PXI express based new control system was installed. Each unit, which consists of an event receiver board, a DAC board, and a ADC board, can set and monitor output current up to 8 pulsed power supply in 16 bit resolution. The timing and control system are integrated in that of the LINAC by using Micro-Research Finland's PXI event receiver board. In terms of software, Windows 8.1 and LabVIEW 2016 were mainly adopted to control the hardware. EPICS channel access (CA) protocol was used to communicate with operator's interface panels. In addition to real-time monitoring by EPICS CA and logging by CSS archiver every 10 s, data are logged every shot (every 20 ms) in the text file together with timestamp, shot ID and destination. At present, thirteen units are stably in operation to control 64 magnets. Further installation of the system is planned in 2018.
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WEPAK015	Beam Gate Control System for SuperKEKB	2124
	H. Kaji, Y. Ohnishi, S. Sasaki, M. Satoh, H. Sugimura KEK, Ibaraki, Japan Y. Iitsuka EJIT, Hitachi, Ibaraki, Japan T. Kudou Mitsubishi Electric System & Service Co., Ltd, Tsukuba, Japan
	The electron beam pulses of injector linac for the SuperKEKB collider are enabled and disabled by Beam Gate control system. This system controls the delivery of triggers to the electron guns at the injector. Also, the septum and kicker magnets for injection point of main ring are controlled with this Beam Gate to avoid unnecessary operation and to prolong their lifetime. The Beam Gate synchronizes the enabling and disabling operations of these hardware even though they are about 1km distant. Besides, from the phase-2 operation, the kicker and septum magnets for newly constructed damping ring becomes controlled apparatus of this system. We develop the new Beam Gate control system with the Event Timing System network. The new system improves the unsatisfied performance of Beam Gate in the phase-1 operation and realizes the complicated control for phase-2. The advantages of new system are: the control signal is delivered via Event nettork, so that we do not need to cable new network. The enabling and disabling operations for distant hardware are surely synchronized by the Event Timing System. H. Kaji et al., "Construction and Commissioning Event Timing System at SuperKEKB", Proceedings of IPAC14, Dresden, Germany (2014).
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WEPAK016	RF Monitor System for SuperKEKB Injector Linac	2128
	H. Katagiri, M. Akemoto, D.A. Arakawa, T. Matsumotopresenter, T. Miura, F. Qiu, Y. Yano KEK, Ibaraki, Japan
	A new radio frequency (RF) monitor system for the SuperKEKB project has been developed at the KEK in-jector linac. The RF monitor unit, which consists of an analog I/Q demodulator, ADC/DAC board, and FPGA board achieved 50-Hz data acquisition and beam mode identification. On the RF monitor, the amplitude and phase measurement precision has achieved 0.1% rms and 0.1° rms, respectively. Sixty RF monitor units have been installed in the linac. The present status of the RF monitor system will be re-ported.
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WEPAK017	Low-level RF System for the SuperKEKB Injector LINAC	2131
	T. Matsumoto, M. Akemoto, D.A. Arakawa, H. Katagiri, T. Miura, F. Qiu, Y. Yano KEK, Ibaraki, Japan M. Akemoto, T. Miura, F. Qiu Sokendai, Ibaraki, Japan
	The low-level RF (LLRF) system of the KEK injector linac has been upgraded for the SuperKEKB. As a major change, a low-emittance and high-current RF gun was installed to satisfy 40-times higher luminosity at the SuperKEKB. In order to balance the stable RF gun operation and the electron/positron beam acceleration, the phase shifter is developed and the configuration of main drive system in the LLRF system is modified. The present status and future plan of the LLRF system upgraded for the SuperKEKB will be reported.
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WEPAK018	LLRF Control Unit for SuperKEKB Injector Linac	2134
	T. Miura, M. Akemoto, D.A. Arakawa, H. Katagiri, T. Matsumotopresenter, F. Qiu, Y. Yano KEK, Ibaraki, Japan N. Liu Sokendai, Ibaraki, Japan
	The low-level RF (LLRF) control unit based on the digital system has been developed for a stable and high precision pulse modulation for the SuperKEKB. The RF pulse is changed at a 50-Hz repetition rate for the top-up injection to four different rings by the event system. The LLRF control unit has not only the pulse modulator, but also other functions: VSWR meter, RF monitor, event receiver (EVR), and pulse-shortening detection.
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Paper

Title

Page

Intense Neutrino Source Front End Beam Diagnostics System R&D

2077

K. Yonehara, M.D. Balcazar, A. Moretti, A.V. Tollestrup, A.C. Watts, R.M. Zwaska
Fermilab, Batavia, Illinois, USA
M.A. Cummings, A. Dudas, R.P. Johnson, G.M. Kazakevich, M.L. Neubauer
Muons, Inc, Illinois, USA

Funding: Work supported by Fermilab Research Alliance, LLC under Contract No. DE-AC02-07CH11359 and DOE STTR Grant, No. DE-SC0013795.
We overview the front end beam diagnostic system R&D to prepare operation of a multi-MW proton beam for intensity frontier Neutrino experiments. One of critical issues is shorter life time of a detector with higher beam intensity due to radiation damage. We show a possible improvement of the existing ion chamber based detector, and a study of a conceptually new radiation-robust detector which is based on a gas-filled RF resonator.

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WEPAK003

Effect of Model Errors on the Closed Orbit Correction at the SIS18 Synchrotron of GSI

2080

SUSPL057

use link to see paper's listing under its alternate paper code

S.H. Mirza, P. Forck, H. Klingbeil, R. Singhpresenter
GSI, Darmstadt, Germany
H. Klingbeil
TEMF, TU Darmstadt, Darmstadt, Germany

Funding: Deutscher Akademischer Austauschdienst under contract No. 91605207
A fast closed orbit feedback system (bandwidth in the order of 1 kHz) is under development at the GSI SIS18 synchrotron for the orbit correction from injection to extraction including the acceleration ramp. The static process model, represented as the orbit response matrix (ORM), is subjected to the systematic optics changes during ramp e.g. beta function and phase advance variations at the locations of BPMs and steerers. In addition to these systematic variations, model mismatches may arise from dipole and quadrupole magnet errors, space charge dependent tune shift as well as BPM and steerer calibration errors. In this contribution, the effects of these model errors on the closed orbit correction are investigated which is necessary for the robust stability analysis of the feedback controller. For the robustness tests, the traditional SVD-based matrix pseudo-inversion is compared to a Fourier-based analysis. The results are achieved by detailed simulations in MADX.

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WEPAK004

Beam Instrumentation for CRYRING@ESR

2084

A. Reiter, C. Andre, H. Bräuning, C. Dorn, P. Forck, R. Haseitl, T. Hoffmann, W. Kaufmann, N. Kotovski, P. Kowina, K. Lang, R. Lonsing, P.B. Miedzik, T. Milosic, A. Petit, H. Reeg, C. Schmidt, M. Schwickert, T. Sieber, R. Singh, G. Vorobjev, B. Walasek-Höhne, M. Witthaus
GSI, Darmstadt, Germany

We present the beam instrumentation of CRYRING@ESR, a low-energy experiment facility at the GSI Helmholtz-Centre for heavy ion research. The 1.44 Tm synchrotron and storage ring, formerly hosted at the Manne Siegbahn laboratory in Stockholm, Sweden, was modified in its configuration and installed behind the existing ESR, the experimental storage ring. As the first machine within the ongoing FAIR project, the facility for antiproton and ion research, it is built on the future timing system and frameworks for data supply and acquisition. Throughout the past year CRYRING was commissioned including its electron cooler with hydrogen beams from the local linear accelerator. Storage, acceleration and cooling have been demonstrated. The contribution provides an overview of the beam instrumentation. The design of the detector systems and their current performance are presented. Emphasis is given to beam position monitors, detectors for intensity measurements, and the ionization profile monitors.

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WEPAK005

A Cryogenic Current Comparators (CCC) Customized for FAIR-Project

2088

SUSPF098

use link to see paper's listing under its alternate paper code

J. Golm, R. Neubert, F. Schmidl, P. Seidel
FSU Jena, Jena, Germany
J. Golm, T. Stöhlker, V. Tympel
HIJ, Jena, Germany
D.M. Haider, F. Kurian, M. Schwickert, T. Sieber, T. Stöhlker
GSI, Darmstadt, Germany
R. Neubert
Thuringia Observatory Tautenburg, Tautenburg, Germany
M. Schmelz, R. Stolz
IPHT, Jena, Germany
T. Stöhlker
IOQ, Jena, Germany
V. Zakosarenko
Supracon AG, Jena, Germany

The principle of non-destructive measurement of ion beams by detection of the azimuthal magnetic field, using low temperature Superconducting Quantum Interference Device (SQUID) sensors, has been established at GSI already in the mid 90's. After more recent developments at Jena, GSI and CERN, a CCC was installed in the CERN Antiproton Decelerator (AD) and is operated there routinely as the first stand-alone CCC system. For the Facility for Antiproton and Ion Research (FAIR) a new version of the CCC with eXtended Dimensions (CCC-XD) - especially with a larger inner diameter and adapted parameters - was constructed and first lab tests have already been performed. In parallel, a concept for a dedicated UHV beamline cryostat has been worked out. The CCC-XD system - together with the new cryostat - will be ready for testing in the CRYRING at GSI before the end of 2018. In this contribution, experimental results for the resolution, frequency range, slew rate and pulse-signal obtained by electrical laboratory measurements with the CCC-XD are presented.

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WEPAK006

Bunch Shape Measurements at the GSI CW-Linac Prototype

2091

T. Sieber, W.A. Barth, P. Forck, V. Gettmann, M. Heilmann, H. Reeg, A. Reiter, S. Yaramyshev
GSI, Darmstadt, Germany
F.D. Dziuba, T. Kürzeder, M. Miski-Oglu
HIM, Mainz, Germany
A. Feschenko, S.A. Gavrilov
RAS/INR, Moscow, Russia

The existing GSI accelerator will become the injector for FAIR. To preserve and enhance the current experimental program at UNILAC, a new Linac is under development, which shall run in parallel to the FAIR injector, providing cw-beams of ions at energies from 3.5 - 7.3 MeV/u. For this cw-Linac a superconducting prototype cavity has been developed and was first operated with beam in summer 2017. The resonator is a cross-bar H-structure (CH) of 0.7 m length, with a resonant frequency of 216.8 MHz. It has been installed behind the GSI High Charge State Injector (HLI), which provided 10⁸ MHz bunches of 1.4 MeV/u Ar⁶⁺/9+/11+ ions at a duty cycle of 25 %. Due to the frequency jump and small longitudinal acceptance of the CH, proper matching of the HLI beam to the prototype was required. The bunch properties of the injected beam as well as the effect of different phase- and amplitude-settings of the cavity were measured in detail with a bunch shape monitor (BSM) fabricated at INR, Moscow, while the mean energy was analyzed by time of flight method. In this contribution, the bunch shape measurements are described and the capabilities of the used BSM measurement principle are discussed.

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WEPAK007

Slow Extraction Spill Characterization From Micro to Milli-Second Scale

2095

R. Singh, P. Boutachkov, P. Forck, S. Sorge, H. Welker
GSI, Darmstadt, Germany

This contribution deals with the topic of slow extraction spill quality characterization based on the measurements performed at GSI SIS-18. The sensitivity of the spill to power supply ripples are studied by introducing external ripples. An estimate of sources of inherent power supply ripples along with ripple magnitude are thus obtained. Spill characterization in time and frequency domain are discussed and exemplified by a typical spill and the differences from an ideal or Poisson spill. An appropriate spill characterization aims to provide a suitable abstraction for communication about the spill quality requirements between accelerator operations and users.

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WEPAK008

Reconstructing Space-Charge Distorted IPM Profiles with Machine Learning Algorithms

2099

D.M. Vilsmeier, M. Sapinski, R. Singhpresenter
GSI, Darmstadt, Germany
J.W. Storey
CERN, Geneva, Switzerland

Measurements of undistorted transverse profiles via Ionization Profile Monitors (IPMs) may pose a great challenge for high brightness or high energy beams due to interaction of ionized electrons or ions with the electromagnetic field of the beam. This contribution presents application of various machine learning algorithms to the problem of reconstructing the actual beam profile from measured profiles that are distorted by beam space-charge interaction. (Generalized) linear regression, artificial neural network and support vector machine algorithms are trained with simulation data, obtained from the Virtual-IPM simulation tool, in order to learn the relation between distorted profiles and original beam dimension. The performance of different algorithms is assessed and the obtained results are very promising for testing with simulation data.

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WEPAK009

Applications of the Interferometric Beam Size Monitor at BESSY II

2103

M. Koopmans, P. Goslawski, J.G. Hwang, A. Jankowiak, M. Ries, A. Schälicke, G. Schiwietz
HZB, Berlin, Germany

For the upgrade project of the BESSY~II storage ring to BESSY~VSR * an interferometric beam size monitor was designed and set up. Since this system uses visible light it can be upgraded efficiently to provide bunch resolved measurements. These are required for machine commissioning, development and to ensure long term quality and stability of user operation of BESSY~VSR. Various applications of the system are outlined and measurements are presented.
* A. Jankowiak et al., eds., BESSY VSR Technical Design Study, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Germany, June 2015. DOI: 10.5442/R0001

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WEPAK010

Simulations and Measurements of the BPM Non Linearity and Kicker Timing Influence on the Tune Shift With Amplitude (TSWA) Measurement at BESSY II

2107

F. Kramer, P. Goslawski, J.G. Hwang, A. Jankowiak, P. Kuske, M. Ruprecht, A. Schälicke
HZB, Berlin, Germany

The Tune Shift With Amplitude (TSWA) does not only determine the position of the stable fix points for the Transverse Resonant Island Buckets (TRIBs) but also represents a global observable for the nonlinear optics in general. For theoretical investigations of the TRIBs a reliable nonlinear optics of the machine is required and thus all measurable global observables for the nonlinear optics are of great interest. The measurement of the TSWA for the BESSY II standard optics was performed using an injection kicker to excite high amplitude betatron oscillations and then extract the amplitude dependant frequency from the synchrotron radiation damped oscillation with a Hilbert transformation. With TRIBs optics the injection kicker was not able to sufficienty excite the beam. The impact and correctability of the BPM nonlinearity at the reached amplitudes and the reason for the failure of the excitation method for our TRIBs optics shall be looked onto in this paper.

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WEPAK011

Development of the Electron-Beam Diagnostics for the Future BESSY-VSR Storage Ring

2110

G. Schiwietz, J.G. Hwang, M. Koopmans, M. Ries, A. Schälicke
HZB, Berlin, Germany

This contribution focusses on the different types of new or improved electron-beam monitors at BESSY II for bunch resolved measurements under future BESSY-VSR conditions. A new diagnostics platform, involving three different dipole beam lines will be built for different di-pole-related optical and THz methods. Our main concepts for robust future monitors for bunch length, beam size and position are presented in the following.

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WEPAK012

Developing Kalman Filter Based Detuning Control with a Digital SRF CW Cavity Simulator

2114

A. Ushakov, P. Echevarria, A. Neumann
HZB, Berlin, Germany

Funding: Work supported by German Bundesministerium für Bildung und Forschung, Land Berlin, and grants of the Helmholtz Association
Continuous wave operated superconducting cavities experiencing small net beam loading and thus operate potentially at narrow bandwidth require precise detuning control to reach the high stability requirements for RF fields within facilities as FEL or ERL based photon sources. Especially microphonics compensation down to sub-hertz detuning regime besides improving stability reduces the risk of rise of Lorentz force detuning driven ponderomotive instabilities. Usually the complex and second order nature of the mechanical to RF detuning transfer functions of cavity and cavity-tuner system require for more advanced control schemes. In this paper we will show the application of a Kalman filter based detuning estimator algorithm first introduced during IPAC2017 [1] to the SRF cavity simulator developed at Helmholtz Zentrum Berlin [2]. Results using the algorithm in observer mode to detuning compensation attempts in closed loop mode are presented.
* A. Ushakov, P. Echevarria, A. Neumann, Proc. of IPAC 2017, Copenhagen, Denmark

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WEPAK013

SRF Cavity Simulator for LLRF Algorithms Debugging

2118

P. Echevarria, J. Knobloch, A. Neumann, A. Ushakovpresenter
HZB, Berlin, Germany
E. Aldekoa, J. Jugo
University of the Basque Country, Faculty of Science and Technology, Bilbao, Spain

Funding: Work supported by German Bundesministerium für Bildung und Forschung, Land Berlin, and grants of Helmholtz Association
The availability of niobium superconducting cavities, ei-ther due to a lack of a real cavity or due to the time needed for the experiment set up (vacuum, cryogenics, cabling, etc.), is limited, and thus it can block or delay the develop-ment of new algorithms such as low level RF control. Hardware-in-the-loop simulations, where an actual cavity is replaced by an electronics system, can help to solve this issue. In this paper we present a Cavity Simulator imple-mented in a National Instruments PXI equipped with an FPGA module. This module operates with one intermedi-ate frequency input which is IQ-demodulated and fed to the electrical cavity's model, where the transmitted and re-flected voltages are calculated and IQ-modulated to gener-ate two intermediate frequency outputs. Some more ad-vanced features such as mechanical vibration modes driven by Lorentz-force detuning or external microphonics have also been implemented. This Cavity Simulator is planned to be connected to an mTCA chassis to close the loop with a LLRF control system.

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WEPAK014

A New Pulse Magnet Control System in the KEK Electron Positron LINAC

2121

Y. Enomoto, K. Furukawa, T. Natsui, M. Satoh
KEK, Ibaraki, Japan
H.S. Saotome
Kanto Information Service (KIS), Accelerator Group, Ibaraki, Japan

In 2017, sixty-four pules magnets were installed in the KEK e⁺/e⁻ LINAC for simultaneous injection to four different rings. Since each ring requires different injection energy, magnetic field in the LINAC has to be changed shot by shot (every 20 ms) according to the destination of the beam. To realize such operation, a PXI express based new control system was installed. Each unit, which consists of an event receiver board, a DAC board, and a ADC board, can set and monitor output current up to 8 pulsed power supply in 16 bit resolution. The timing and control system are integrated in that of the LINAC by using Micro-Research Finland's PXI event receiver board. In terms of software, Windows 8.1 and LabVIEW 2016 were mainly adopted to control the hardware. EPICS channel access (CA) protocol was used to communicate with operator's interface panels. In addition to real-time monitoring by EPICS CA and logging by CSS archiver every 10 s, data are logged every shot (every 20 ms) in the text file together with timestamp, shot ID and destination. At present, thirteen units are stably in operation to control 64 magnets. Further installation of the system is planned in 2018.

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WEPAK015

Beam Gate Control System for SuperKEKB

2124

H. Kaji, Y. Ohnishi, S. Sasaki, M. Satoh, H. Sugimura
KEK, Ibaraki, Japan
Y. Iitsuka
EJIT, Hitachi, Ibaraki, Japan
T. Kudou
Mitsubishi Electric System & Service Co., Ltd, Tsukuba, Japan

The electron beam pulses of injector linac for the SuperKEKB collider are enabled and disabled by Beam Gate control system. This system controls the delivery of triggers to the electron guns at the injector. Also, the septum and kicker magnets for injection point of main ring are controlled with this Beam Gate to avoid unnecessary operation and to prolong their lifetime. The Beam Gate synchronizes the enabling and disabling operations of these hardware even though they are about 1km distant. Besides, from the phase-2 operation, the kicker and septum magnets for newly constructed damping ring becomes controlled apparatus of this system. We develop the new Beam Gate control system with the Event Timing System network*. The new system improves the unsatisfied performance of Beam Gate in the phase-1 operation and realizes the complicated control for phase-2. The advantages of new system are: the control signal is delivered via Event nettork, so that we do not need to cable new network. The enabling and disabling operations for distant hardware are surely synchronized by the Event Timing System.
* H. Kaji et al., "Construction and Commissioning Event Timing System at SuperKEKB", Proceedings of IPAC14, Dresden, Germany (2014).

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WEPAK016

RF Monitor System for SuperKEKB Injector Linac

2128

H. Katagiri, M. Akemoto, D.A. Arakawa, T. Matsumotopresenter, T. Miura, F. Qiu, Y. Yano
KEK, Ibaraki, Japan

A new radio frequency (RF) monitor system for the SuperKEKB project has been developed at the KEK in-jector linac. The RF monitor unit, which consists of an analog I/Q demodulator, ADC/DAC board, and FPGA board achieved 50-Hz data acquisition and beam mode identification. On the RF monitor, the amplitude and phase measurement precision has achieved 0.1% rms and 0.1° rms, respectively. Sixty RF monitor units have been installed in the linac. The present status of the RF monitor system will be re-ported.

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WEPAK017

Low-level RF System for the SuperKEKB Injector LINAC

2131

T. Matsumoto, M. Akemoto, D.A. Arakawa, H. Katagiri, T. Miura, F. Qiu, Y. Yano
KEK, Ibaraki, Japan
M. Akemoto, T. Miura, F. Qiu
Sokendai, Ibaraki, Japan

The low-level RF (LLRF) system of the KEK injector linac has been upgraded for the SuperKEKB. As a major change, a low-emittance and high-current RF gun was installed to satisfy 40-times higher luminosity at the SuperKEKB. In order to balance the stable RF gun operation and the electron/positron beam acceleration, the phase shifter is developed and the configuration of main drive system in the LLRF system is modified. The present status and future plan of the LLRF system upgraded for the SuperKEKB will be reported.

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WEPAK018

LLRF Control Unit for SuperKEKB Injector Linac

2134

T. Miura, M. Akemoto, D.A. Arakawa, H. Katagiri, T. Matsumotopresenter, F. Qiu, Y. Yano
KEK, Ibaraki, Japan
N. Liu
Sokendai, Ibaraki, Japan

The low-level RF (LLRF) control unit based on the digital system has been developed for a stable and high precision pulse modulation for the SuperKEKB. The RF pulse is changed at a 50-Hz repetition rate for the top-up injection to four different rings by the event system. The LLRF control unit has not only the pulse modulator, but also other functions: VSWR meter, RF monitor, event receiver (EVR), and pulse-shortening detection.

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