IPAC2018 - List of Authors (Klingbeil, H.)

Paper	Title	Page
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. Singh 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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAK003
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WEPML031	The New Broadband Accelerating System for the SIS18 Upgrade at GSI	2755
	P. Hülsmann, R. Balß, H. Klingbeil, U. Laier, K.-P. Ningel, C. Thielmann, B. Zipfel GSI, Darmstadt, Germany
	In this contribution, a new SIS18 rf accelerating system is presented whose cavities are based on magnetic alloy materials. The rf system works at harmonic number h=2 (f=0,43- to 2,8 MHz) and provides the necessary accelerating voltage (up to 50kVp) for SIS18 injector operation for FAIR with high intensity heavy ion beams in a fast operation mode with up to three cycles per second. The paper focusses on the cavity part and its cooling issues as well as the broadband characteristics. Due the lossy magnetic alloy ring core filling, which consists of high permeability Finemet FT3M ring cores (HITACHI), the cavities show a broadband behaviour and thus no cavity tuning during the acceleration ramp is necessary. To keep the bandwidth of the cavities as broad as possible they are cooled by a special mineral oil with low permittivity. Also the beam impedance and the power consumption of the rf system are discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML031
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WEPML032	The FAIR-SIS100 Bunch Compressor RF Station	2759
	H.G. König, R. Balß, P. Hülsmann, H. Klingbeil, P.J. Spiller GSI, Darmstadt, Germany R. Gesche, J.H. Scherer Aurion Anlagentechnik GmbH, Seligenstadt, Germany A. Morato, C. Morri, G.T. Taddia OCEM, Valsamoggia, Italy
	In the frame of the Facility for Antiproton and Ion Research (FAIR) 9 bunch compressor RF stations were ordered for the first stage of realization of the SIS100 synchrotron. For RF gymnastics referred to as bunch rotation, one RF station has to provide a sudden rise in gap voltage of up to 40 kVp within less than 30 μs. The system is designed for a maximum RF burst of 3 ms per second. The RF frequency will be pre-selectable between 310 kHz and 560 kHz at a harmonic number of h=2 with respect to the beam. Compressed bunches with a peak current > 150 A and a width < 50 ns are the goal. For this purpose, a 1.218 m long cavity was designed using iron-based magnetic alloy cores. Variable vacuum capacitors are attached for tuning. The cavity is driven by a cross-coupled push-pull tetrode amplifier. This scheme minimizes the influence of the tetrode's DC current at the working point to the cores. The energy for the pulsed system is stored in a relatively small capacitor bank which will be charged semi-continuously and a voltage-stabilizing device is added. Cavity and power amplifier were realized by AURION Anlagentechnik GmbH ' the power supply unit is designed and built by OCEM Power Electronics.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML032
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WEPML033	The FAIR-SIS100 Accelerating RF Station	2762
	H.G. König, R. Balß, H. Klingbeil, U. Laier, D.E.M. Lens, P.J. Spiller GSI, Darmstadt, Germany G. Blokesch, F. Wieschenberg Ampegon PPT GmbH, Dortmund, Germany K. Dunkel, M. Eisengruber, J.H. Hottenbacher RI Research Instruments GmbH, Bergisch Gladbach, Germany C. Hiltbrunner Ampegon AG, Turgi, Switzerland
	For the Facility for Antiproton and Ion Research (FAIR) 14 ferrite loaded accelerating RF stations are planned for the first stage of realization of the SIS100 synchrotron. Each RF station has to provide a total peak gap voltage of up to 20 kVp in CW operation - tuneable in the range of 1.1 MHz up to 3.2 MHz to allow ion beam acceleration and beam gymnastics at different harmonic numbers and energy levels in the new facility. Each RF station consists of a tuneable ferrite cavity, a single ended tetrode amplifier and a dedicated power supply and control unit (PSU) ' including two bias current supplies for cavity- and control-grid(G1)-circuit-tuning. The ferrite cavity is based on the SIS18 cavity concept but has to provide a 1.25 times higher gap voltage of 20 kVp over a total length of 3 meters. The realization is done by a consortium consisting of RI Research Instruments GmbH as consortium leader and manufacturer of the cavity, Ampegon PPT GmbH (for the tetrode amplifier) and Ampegon AG (for the power supply unit). In this contribution, the system design is discussed, and commissioning results are presented. All main parameters are achieved with the RF station described.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML033
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WEPML034	Design and Commissioning of the RF System of the Collector Ring at FAIR	2765
	U. Laier, R. Balß, A. Dolinskyy, P. Hülsmann, H. Klingbeil, T. Winnefeld GSI, Darmstadt, Germany G. Blokesch, F. Wieschenberg Ampegon PPT GmbH, Dortmund, Germany K. Dunkel, M. Eisengruber, J.H. Hottenbacher RI Research Instruments GmbH, Bergisch Gladbach, Germany C. Morri, M.P. Pretelli, G.T. Taddia OCEM, Valsamoggia, Italy
	The Collector Ring (CR), a storage ring intended to perform efficient cooling of secondary beams, is under construction at GSI in the scope of the FAIR project. The RF system of the CR has to provide a frequency range from 1.1 to 1.5 MHz and pulsed gap voltages of up to 200 kVp (0.2 to 1 Hz, max. 10^-3 duty cycle) and up to 10 kVp in CW operation. Five identical RF stations will be built. Each RF station consists of an inductively loaded cavity, a tetrode based power amplifier, a semiconductor driver amplifier, a switch mode power supply and two digital feedback loops. The main components of the RF station are designed, built and commissioned in close collaboration between GSI and three companies: RI Research Instruments GmbH, Ampegon PPT GmbH and OCEM Energy Technology SRL. In 2016, the first of five RF stations has been integrated at GSI. In 2017 the system was successfully commissioned to demonstrate that all envisaged parameters have been achieved. This contribution will present the requirements imposed the system, the principal design of the overall system as well as of its key components, and the results of the commissioning of the first RF station.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML034
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THYGBF3	Challenges of FAIR Phase 0	2947
	M. Bai, A. Adonin, S. Appel, R. Bär, M.C. Bellachioma, U. Blell, C. Dimopoulou, G. Franchetti, O. Geithner, P. Gerhard, L. Groening, F. Herfurth, R. Hess, R. Hollinger, H.C. Hüther, H. Klingbeil, A. Krämer, S.A. Litvinov, F. Maimone, D. Ondreka, N. Pyka, S. Reimann, A. Reiter, M. Sapinski, B. Schlitt, G. Schreiber, M. Schwickert, D. Severin, R. Singh, P.J. Spiller, J. Stadlmann, M. Steck, R.J. Steinhagen, K. Tinschert, M. Vossberg, G. Walter, U. Weinrich GSI, Darmstadt, Germany
	After two-year's shutdown, the GSI accelerators plus the latest addition of storage ring CRYRING, will be back into operation in 2018 as the FAIR phase 0 with the goal to fulfill the needs of scientific community and the FAIR accelerators and detector development. Even though GSI has been well known for its operation of a variety of ion beams ranging from proton up to uranium for multi research areas such as nuclear physics, astrophysics, biophysics, material science, the upcoming beam time faces a number of challenges in re-commissioning its existing circular accelerators with brand new control system and upgrade of beam instrumentations, as well as in rising failures of dated components and systems. The cycling synchrotron SIS18 has been undergoing a set of upgrade measures for fulfilling future FAIR operation, among which many measures will also be commissioned during the upcoming beam time. This paper presents the highlights of the challenges such as re-establishing the high intensity heavy ion operation as well as parallel operation mode for serving multi users. The status of preparation including commissioning results will also be reported.
	Slides THYGBF3 [2.948 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THYGBF3
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THPML088	Cavity Impedance Reduction Strategies During Multi Cavity Operation in the SIS100 High Intensity Hadron Synchrotron	4863
	D. Mihailescu Stoica, D. Domont-Yankulova Technische Universität Darmstadt (TU Darmstadt, RMR), Darmstadt, Germany D. Domont-Yankulova, H. Klingbeil TEMF, TU Darmstadt, Darmstadt, Germany H. Klingbeil, D.E.M. Lens GSI, Darmstadt, Germany
	Funding: Supported by GSI Helmholtzzentrum für Schwerionenforschung GmbH The planned SIS100 heavy ion synchrotron at the GSI Helmholtzzentrum für Schwerionenforschung will possess twenty ferrite accelerating cavities in its final stage of extension. As at injection and at flat top during slow extraction of the planned acceleration cycles the RF voltage will be relatively low, not all cavities will be active in this part of operation. It is important to analyse the impact of the inactive cavities on the overall RF voltage and subsequently their implication on the longitudinal particle dynamics. Classical approaches for reducing the beam impedance consist of active detuning of the cavities to pre-described parking frequencies. The fact that two out of ten buckets have to stay empty in all SIS100 scenarios is of particular interest as additional frequency components appear in the excitatory beam current, which have to be considered when the cavity is detuned. Therefore multi-cavity particle tracking simulations, consisting of twenty cavities and their attached LLRF control systems, are carried out in order to analyse different possibilities to minimize the impact on the beam dynamics and emittance growth.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML088
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THPML089	Tuning of 3-tap Bandpass Filter During Acceleration for Longitudinal Beam Stabilization at FAIR	4866
	B.R. Reichardt, D. Domont-Yankulova Technische Universität Darmstadt (TU Darmstadt, RMR), Darmstadt, Germany D. Domont-Yankulova, H. Klingbeil TEMF, TU Darmstadt, Darmstadt, Germany H. Klingbeil, D.E.M. Lens GSI, Darmstadt, Germany
	During acceleration in the heavy-ion synchrotrons SIS18/SIS100 at GSI/FAIR longitudinal beam oscillations are expected to occur. To reduce longitudinal emittance blow-up, dedi- cated LLRF beam feedback systems are planned. To date, damping of longitudinal beam oscillations has been demon- strated in SIS18 machine experiments with a 3-tap filter controller (e.g. ), which is robust in regard to control pa- rameters and also to noise. On acceleration ramps the control parameters have to be adjusted to the varying synchrotron frequency. Previous results from beam experiments at GSI indicate that a proportional tuning rule for one parameter and an inversely proportional tuning rule for a second parameter is feasible, but the obtained damping rate may not be opti- mal for all synchrotron frequencies during the ramp. In this work, macro-particle simulations are performed to evaluate, whether it is sufficient to adjust the control parameters pro- portionally (inversely proportionally) to the change in the linear synchrotron frequency, or if it is necessary to take more pa- rameters, such as bunch-length and synchronous phase, into account to achieve stability and a considerable high damping rate for excited longitudinal dipole beam oscillations. This is done for single- and dual-harmonic acceleration ramps. H. Klingbeil et al., "A Digital Beam-Phase Control System for Heavy-Ion Synchrotrons", in IEEE Transactions on Nuclear Science, vol. 54, no. 6, pp. 2604-2610, Dec. 2007.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML089
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THPML123	The ESR Barrier-Bucket LLRF System - Design and First Results	4964
	J. Harzheim, D. Domont-Yankulova, K. Groß, H. Klingbeil TEMF, TU Darmstadt, Darmstadt, Germany M. Frey, H. Klingbeil, D.E.M. Lens GSI, Darmstadt, Germany
	At GSI, Darmstadt, Germany, a Barrier-Bucket (BB) RF System is currently under development for the Experimental Storage Ring (ESR). The system consists of two broadband RF cavities, each driven by a solid state amplifier, with the purpose to produce two voltage pulses per beam revolution. This will enable highly sophisticated longitudinal beam manipulations like longitudinal capture, compression and decompression or stacking of the beam. For the LLRF System, several requirements have to be fulfilled. Besides high standards concerning the pulsed gap signal quality (e.g. ringing <2.5%), the system has to provide the flexibility for adiabatic voltage ramp-up and adiabatic pulse shifting with high timing accuracy. A connection to the FAIR Central Control System (CCS) is necessary, as amplitude and phase ramp data will be provided by the CCS. In this contribution, the structure of the ESR BB LLRF system is presented together with experimental results from the first version of the system, which will be installed in the ESR in March 2018.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML123
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Paper

Title

Page

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. Singh
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.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAK003

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WEPML031

The New Broadband Accelerating System for the SIS18 Upgrade at GSI

2755

P. Hülsmann, R. Balß, H. Klingbeil, U. Laier, K.-P. Ningel, C. Thielmann, B. Zipfel
GSI, Darmstadt, Germany

In this contribution, a new SIS18 rf accelerating system is presented whose cavities are based on magnetic alloy materials. The rf system works at harmonic number h=2 (f=0,43- to 2,8 MHz) and provides the necessary accelerating voltage (up to 50kVp) for SIS18 injector operation for FAIR with high intensity heavy ion beams in a fast operation mode with up to three cycles per second. The paper focusses on the cavity part and its cooling issues as well as the broadband characteristics. Due the lossy magnetic alloy ring core filling, which consists of high permeability Finemet FT3M ring cores (HITACHI), the cavities show a broadband behaviour and thus no cavity tuning during the acceleration ramp is necessary. To keep the bandwidth of the cavities as broad as possible they are cooled by a special mineral oil with low permittivity. Also the beam impedance and the power consumption of the rf system are discussed.

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WEPML032

The FAIR-SIS100 Bunch Compressor RF Station

2759

H.G. König, R. Balß, P. Hülsmann, H. Klingbeil, P.J. Spiller
GSI, Darmstadt, Germany
R. Gesche, J.H. Scherer
Aurion Anlagentechnik GmbH, Seligenstadt, Germany
A. Morato, C. Morri, G.T. Taddia
OCEM, Valsamoggia, Italy

In the frame of the Facility for Antiproton and Ion Research (FAIR) 9 bunch compressor RF stations were ordered for the first stage of realization of the SIS100 synchrotron. For RF gymnastics referred to as bunch rotation, one RF station has to provide a sudden rise in gap voltage of up to 40 kVp within less than 30 μs. The system is designed for a maximum RF burst of 3 ms per second. The RF frequency will be pre-selectable between 310 kHz and 560 kHz at a harmonic number of h=2 with respect to the beam. Compressed bunches with a peak current > 150 A and a width < 50 ns are the goal. For this purpose, a 1.218 m long cavity was designed using iron-based magnetic alloy cores. Variable vacuum capacitors are attached for tuning. The cavity is driven by a cross-coupled push-pull tetrode amplifier. This scheme minimizes the influence of the tetrode's DC current at the working point to the cores. The energy for the pulsed system is stored in a relatively small capacitor bank which will be charged semi-continuously and a voltage-stabilizing device is added. Cavity and power amplifier were realized by AURION Anlagentechnik GmbH ' the power supply unit is designed and built by OCEM Power Electronics.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML032

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WEPML033

The FAIR-SIS100 Accelerating RF Station

2762

H.G. König, R. Balß, H. Klingbeil, U. Laier, D.E.M. Lens, P.J. Spiller
GSI, Darmstadt, Germany
G. Blokesch, F. Wieschenberg
Ampegon PPT GmbH, Dortmund, Germany
K. Dunkel, M. Eisengruber, J.H. Hottenbacher
RI Research Instruments GmbH, Bergisch Gladbach, Germany
C. Hiltbrunner
Ampegon AG, Turgi, Switzerland

For the Facility for Antiproton and Ion Research (FAIR) 14 ferrite loaded accelerating RF stations are planned for the first stage of realization of the SIS100 synchrotron. Each RF station has to provide a total peak gap voltage of up to 20 kVp in CW operation - tuneable in the range of 1.1 MHz up to 3.2 MHz to allow ion beam acceleration and beam gymnastics at different harmonic numbers and energy levels in the new facility. Each RF station consists of a tuneable ferrite cavity, a single ended tetrode amplifier and a dedicated power supply and control unit (PSU) ' including two bias current supplies for cavity- and control-grid(G1)-circuit-tuning. The ferrite cavity is based on the SIS18 cavity concept but has to provide a 1.25 times higher gap voltage of 20 kVp over a total length of 3 meters. The realization is done by a consortium consisting of RI Research Instruments GmbH as consortium leader and manufacturer of the cavity, Ampegon PPT GmbH (for the tetrode amplifier) and Ampegon AG (for the power supply unit). In this contribution, the system design is discussed, and commissioning results are presented. All main parameters are achieved with the RF station described.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML033

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WEPML034

Design and Commissioning of the RF System of the Collector Ring at FAIR

2765

U. Laier, R. Balß, A. Dolinskyy, P. Hülsmann, H. Klingbeil, T. Winnefeld
GSI, Darmstadt, Germany
G. Blokesch, F. Wieschenberg
Ampegon PPT GmbH, Dortmund, Germany
K. Dunkel, M. Eisengruber, J.H. Hottenbacher
RI Research Instruments GmbH, Bergisch Gladbach, Germany
C. Morri, M.P. Pretelli, G.T. Taddia
OCEM, Valsamoggia, Italy

The Collector Ring (CR), a storage ring intended to perform efficient cooling of secondary beams, is under construction at GSI in the scope of the FAIR project. The RF system of the CR has to provide a frequency range from 1.1 to 1.5 MHz and pulsed gap voltages of up to 200 kVp (0.2 to 1 Hz, max. 10^-3 duty cycle) and up to 10 kVp in CW operation. Five identical RF stations will be built. Each RF station consists of an inductively loaded cavity, a tetrode based power amplifier, a semiconductor driver amplifier, a switch mode power supply and two digital feedback loops. The main components of the RF station are designed, built and commissioned in close collaboration between GSI and three companies: RI Research Instruments GmbH, Ampegon PPT GmbH and OCEM Energy Technology SRL. In 2016, the first of five RF stations has been integrated at GSI. In 2017 the system was successfully commissioned to demonstrate that all envisaged parameters have been achieved. This contribution will present the requirements imposed the system, the principal design of the overall system as well as of its key components, and the results of the commissioning of the first RF station.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML034

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THYGBF3

Challenges of FAIR Phase 0

2947

M. Bai, A. Adonin, S. Appel, R. Bär, M.C. Bellachioma, U. Blell, C. Dimopoulou, G. Franchetti, O. Geithner, P. Gerhard, L. Groening, F. Herfurth, R. Hess, R. Hollinger, H.C. Hüther, H. Klingbeil, A. Krämer, S.A. Litvinov, F. Maimone, D. Ondreka, N. Pyka, S. Reimann, A. Reiter, M. Sapinski, B. Schlitt, G. Schreiber, M. Schwickert, D. Severin, R. Singh, P.J. Spiller, J. Stadlmann, M. Steck, R.J. Steinhagen, K. Tinschert, M. Vossberg, G. Walter, U. Weinrich
GSI, Darmstadt, Germany

After two-year's shutdown, the GSI accelerators plus the latest addition of storage ring CRYRING, will be back into operation in 2018 as the FAIR phase 0 with the goal to fulfill the needs of scientific community and the FAIR accelerators and detector development. Even though GSI has been well known for its operation of a variety of ion beams ranging from proton up to uranium for multi research areas such as nuclear physics, astrophysics, biophysics, material science, the upcoming beam time faces a number of challenges in re-commissioning its existing circular accelerators with brand new control system and upgrade of beam instrumentations, as well as in rising failures of dated components and systems. The cycling synchrotron SIS18 has been undergoing a set of upgrade measures for fulfilling future FAIR operation, among which many measures will also be commissioned during the upcoming beam time. This paper presents the highlights of the challenges such as re-establishing the high intensity heavy ion operation as well as parallel operation mode for serving multi users. The status of preparation including commissioning results will also be reported.

Slides THYGBF3 [2.948 MB]

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THPML088

Cavity Impedance Reduction Strategies During Multi Cavity Operation in the SIS100 High Intensity Hadron Synchrotron

4863

D. Mihailescu Stoica, D. Domont-Yankulova
Technische Universität Darmstadt (TU Darmstadt, RMR), Darmstadt, Germany
D. Domont-Yankulova, H. Klingbeil
TEMF, TU Darmstadt, Darmstadt, Germany
H. Klingbeil, D.E.M. Lens
GSI, Darmstadt, Germany

Funding: Supported by GSI Helmholtzzentrum für Schwerionenforschung GmbH
The planned SIS100 heavy ion synchrotron at the GSI Helmholtzzentrum für Schwerionenforschung will possess twenty ferrite accelerating cavities in its final stage of extension. As at injection and at flat top during slow extraction of the planned acceleration cycles the RF voltage will be relatively low, not all cavities will be active in this part of operation. It is important to analyse the impact of the inactive cavities on the overall RF voltage and subsequently their implication on the longitudinal particle dynamics. Classical approaches for reducing the beam impedance consist of active detuning of the cavities to pre-described parking frequencies. The fact that two out of ten buckets have to stay empty in all SIS100 scenarios is of particular interest as additional frequency components appear in the excitatory beam current, which have to be considered when the cavity is detuned. Therefore multi-cavity particle tracking simulations, consisting of twenty cavities and their attached LLRF control systems, are carried out in order to analyse different possibilities to minimize the impact on the beam dynamics and emittance growth.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML088

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THPML089

Tuning of 3-tap Bandpass Filter During Acceleration for Longitudinal Beam Stabilization at FAIR

4866

B.R. Reichardt, D. Domont-Yankulova
Technische Universität Darmstadt (TU Darmstadt, RMR), Darmstadt, Germany
D. Domont-Yankulova, H. Klingbeil
TEMF, TU Darmstadt, Darmstadt, Germany
H. Klingbeil, D.E.M. Lens
GSI, Darmstadt, Germany

During acceleration in the heavy-ion synchrotrons SIS18/SIS100 at GSI/FAIR longitudinal beam oscillations are expected to occur. To reduce longitudinal emittance blow-up, dedi- cated LLRF beam feedback systems are planned. To date, damping of longitudinal beam oscillations has been demon- strated in SIS18 machine experiments with a 3-tap filter controller (e.g. *), which is robust in regard to control pa- rameters and also to noise. On acceleration ramps the control parameters have to be adjusted to the varying synchrotron frequency. Previous results from beam experiments at GSI indicate that a proportional tuning rule for one parameter and an inversely proportional tuning rule for a second parameter is feasible, but the obtained damping rate may not be opti- mal for all synchrotron frequencies during the ramp. In this work, macro-particle simulations are performed to evaluate, whether it is sufficient to adjust the control parameters pro- portionally (inversely proportionally) to the change in the linear synchrotron frequency, or if it is necessary to take more pa- rameters, such as bunch-length and synchronous phase, into account to achieve stability and a considerable high damping rate for excited longitudinal dipole beam oscillations. This is done for single- and dual-harmonic acceleration ramps.
* H. Klingbeil et al., "A Digital Beam-Phase Control System for Heavy-Ion Synchrotrons", in IEEE Transactions on Nuclear Science, vol. 54, no. 6, pp. 2604-2610, Dec. 2007.

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THPML123

The ESR Barrier-Bucket LLRF System - Design and First Results

4964

J. Harzheim, D. Domont-Yankulova, K. Groß, H. Klingbeil
TEMF, TU Darmstadt, Darmstadt, Germany
M. Frey, H. Klingbeil, D.E.M. Lens
GSI, Darmstadt, Germany

At GSI, Darmstadt, Germany, a Barrier-Bucket (BB) RF System is currently under development for the Experimental Storage Ring (ESR). The system consists of two broadband RF cavities, each driven by a solid state amplifier, with the purpose to produce two voltage pulses per beam revolution. This will enable highly sophisticated longitudinal beam manipulations like longitudinal capture, compression and decompression or stacking of the beam. For the LLRF System, several requirements have to be fulfilled. Besides high standards concerning the pulsed gap signal quality (e.g. ringing <2.5%), the system has to provide the flexibility for adiabatic voltage ramp-up and adiabatic pulse shifting with high timing accuracy. A connection to the FAIR Central Control System (CCS) is necessary, as amplitude and phase ramp data will be provided by the CCS. In this contribution, the structure of the ESR BB LLRF system is presented together with experimental results from the first version of the system, which will be installed in the ESR in March 2018.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML123

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