M. Colja, S. Carrato
University of Trieste, Trieste, Italy
G. Brajnik, R. De Monte
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
Digital processing systems have been proven to often outperform analog elaboration. Indeed, thanks to high-density DSPs and FPGAs, operations in digital domain give results that are impossible to achieve in other ways. On the other side, dealing with this great performance and flexibility is not always straightforward: the processing chain needs to be accurately planned to reach the desired goals, avoiding erratic behaviours in the digital domain. In this paper, we focus on the design and implementation of an FPGA-based digital processor that will be used in the electron beam position monitors of Elettra 2.0. After digitizing the 500 MHz beam signals from the pickups, the system executes a digital down conversion, followed by several filtering and demodulating stages, in order to have a selectable data rate that is suitable for both diagnostics and feedback. The position calculation is also performed in FPGA as well, with the well-known difference-over-sum algorithm. According to results provided by a fixed-point simulation, the overall system has been implemented in an Intel Arria 10 FPGA, demonstrating the correct design functionality that meets the specified requirements.
S.L. Mathisen, T.H. Pacey, R.J. Smith
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
As part of the development of the CLARA electron accelerator at Daresbury Laboratory, a new analog front end for bunch charge measurement has been developed to provide accurate measurements across a wide range of operating charges with repetition rates of up to 400 Hz. The qualification tests of the front end are presented. These include tests of the online calibration system, compared to a bench Faraday cup test setup; online beam test data with a Faraday cup from 1 to 200 pC; online beam test data with a wall current monitor from 1 to 200 pC, and tests using signal processing such as singular value decomposition. This is demonstrated to enable the measurement of bunch charges in the order of 100 fC using both Faraday Cups and Wall Current Monitors.
L. Scomparin, E. Blomley, E. Bründermann, M. Caselle, T. Dritschler, A. Kopmann, A. Mochihashi, A.-S. Müller, A. Santamaria Garcia, P. Schreiber, J.L. Steinmann, M. Weber
KIT, Eggenstein-Leopoldshafen, Germany
T. Boltz
SLAC, Menlo Park, California, USA
Modern particle accelerator facilities allow new and exciting beam properties and operation modes. Traditional real-time control systems, albeit powerful, have bandwidth and latency constraints that limit the range of operating conditions currently made available to users. The capability of Reinforcement Learning to perform self-learning control policies by interacting with the accelerator is intriguing. The extreme dynamic conditions require fast real-time feedback throughout the whole control loop from the diagnostic, with novel and intelligent detector systems, all the way to the interaction with the accelerator components. In this contribution, the novel KINGFISHER framework based on the modern Xilinx Versal devices will be presented. Versal combines several computational engines, specifically combining powerful FPGA logic with programmable AI Engines in a single device. Furthermore, this system can be natively integrated with the fastest beam diagnostic tools already available, i.e. KAPTURE and KALYPSO.
A bunched beam intensity measurement system for the CERN Extra Low ENergy Antiproton (ELENA) ring, using a cylindrical shoe-box electrostatic pick-up from the existing orbit system [1], is presented. The system has been developed to measure very challenging beam cur-rents, as low as 200nA corresponding to intensities of the order of 107 antiprotons circulating with a relativistic beta of the order of 10-2. In this work we derive and show that the turn-by-turn beam intensity is proportional to the baseline of the sum signal and that, despite the AC-coupling of the system, the installed front-end electronics, based on a charge amplifier, not only guarantees the preservation of the bunch shape (up to a few tens of MHz), but also allows for an absolute calibration of the system. In addition, the linearity of the intensity measurements and their inde-pendence with respect to average beam position is evalu-ated using a standard electromagnetic simulation tool. Finally, experimental measurements throughout typical antiproton deceleration cycles are presented and their accuracy and precision are discussed.
C. Takahashi, A. Freitas, V. Hardion, M. Holz, M. Lindberg, M. Sjöström, H. Tarawneh
MAX IV Laboratory, Lund University, Lund, Sweden
Feedforward control loops are used in numerous applications to correct process variables. While feedforward control loops correct process variables according to expected behaviour of a system at any given set point, feedback loops require measurements of the output to correct deviations from the set point. At MAX IV, a generic multi-dimensional input and output feedforward controller was implemented using TANGO Control System. This paper describes the development and use cases of this controller for beam orbit and optics corrections at MAX IV.
S.H. Mirza, A. Aloev, H.T. Duhme, B. Dursun, A. Eichler, S. Jabłoński, J. Klute, F. Ludwig, S. Pfeiffer, H. Schlarb, B. Szczepanski
DESY, Hamburg, Germany
G. Rehm
HZB, Berlin, Germany
PETRA IV is the upcoming low-emittance, 6 GeV, fourth- generation light source at DESY Hamburg. It is based upon a six-bend achromat lattice with additional beamlines as compared to PETRA III. Stringent stability of the electron beam orbit in the ring will be required to achieve diffraction- limited photon beam quality. In this regard, the requirements and the proposed topology of the global orbit feedback system are discussed for expected perturbations. An initial analysis based upon system requirements, design and modelling of the subsystems of the orbit feedback system is also presented
J. Breunlin, G. Felcsuti
MAX IV Laboratory, Lund University, Lund, Sweden
The MAX IV Laboratory, inaugurated in 2016, hosts a 3 GeV ultra-low emittance storage ring, a 1.5 GeV storage ring and a linear accelerator driven Short Pulse Facility to deliver synchrotron radiation to scientific users. A Stability Task Force has been assigned to ensure the delivery of stable beams since early on in the design phase of the laboratory and is continuing its work in an ongoing and multi-disciplinary effort. Measurements of the electron beam stability resulting from the passive stabilization approach taken for the two storage rings will be presented, as well as figures of beam stability with the Fast Orbit Feedback system in operation. Each ID beamline in the 3 GeV storage ring is equipped with a pair photon beam position monitors that are currently used to complement the electron beam position monitors. In the light of the city development around the MAX IV campus, maintaining the good mechanical stability of the laboratory has to be seen as an ongoing effort. A number of studies are being performed to identify possible risks and to decide where measures need to be taken.
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P.H. Baeta Neves Diniz Santos, B. Keil, G. Marinkovic
PSI, Villigen PSI, Switzerland
RF Systems-on-Chip (RFSoCs) are FPGAs with CPUs, multi-GSample/s ADCs and DACs and other components on the same chip. We have evaluated the use of RFSoCs for low-latency multibunch (bunch-by-bunch) feedback and filling pattern (single bunch charge) measurement systems for the Swiss Light Source (SLS) storage ring. First results obtained with an RFSoC evaluation board will be presented.
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S.J. Martens
University of Saskatchewan, Saskatoon, Canada
T. Batten, D. Bertwistle, M.J. Boland
CLS, Saskatoon, Saskatchewan, Canada
A transverse bunch-by-bunch feedback system has been installed in the storage ring at the Canadian Light Source (CLS) to counteract beam instabilities. The 2.9 GeV electron storage ring is 171~m in circumference with 13 insertion devices currently installed, each contributing to the impedance of the ring and lowering the instability threshold. The new Transverse Feedback System (TFBS) provides improved bunch isolation, higher bandwidth amplification and diagnostics to study, understand and damp these instabilities. This paper will show and overview of the system setup, examples of operational performance and results of the diagnostic capabilities, including tune feedback, grow/damp measurements and excite/damp measurements.
S. Jabłoński, H.T. Duhme, B. Dursun, J. Klute, S.H. Mirza, S. Pfeiffer, H. Schlarb
DESY, Hamburg, Germany
PETRA IV will be a new, fourth-generation, high-brilliance synchrotron radiation source in the hard X-ray range. To keep the emittance low at high beam current an active feedback system to damp transverse multi-bunch instabilities is required. The particular challenge to the system is the very low-noise, while maintaining high bandwidth, which is defined by the 2 ns bunch spacing. In this paper, we present the conceptual design of the transverse multi-bunch feedback (T-MBFB) system and technical challenges to fulfill the performance require-ments. An overview is given on the hardware and the method for detecting and damping the coupled-bunch oscillations. Using modern high-speed ADCs enables direct sampling of pulses from beam pick-ups, which removes the necessity for down-converters. Powerful digital signal processing allows not only for the effective feedback implementation, but also for developing versa-tile tools for the machine diagnostics.
S. Preston, L. Bobb, A.F.D. Morgan, T. Olsson
DLS, Oxfordshire, United Kingdom
In the Diamond storage ring, the vertical emittance is kept at 8 pm rad by an emittance feedback which modifies the strengths of skew quadrupoles. A new feedback using a stripline kicker to control the vertical emittance by exciting the beam resonantly at a synchrotron sideband is planned to avoid modification of the optics. This is crucial for the anticipated Diamond-II upgrade of the storage ring, which will have a much smaller equilibrium emittance than the existing machine. A larger coupling is therefore needed to keep the vertical emittance at the same level, potentially reducing the off-axis injection efficiency and lifetime. Measurements of the beam oscillation and emittance have been performed at the existing storage ring to characterise the effects of chromaticity and impedance on the optimal excitation frequency, where the emittance is increased significantly while the beam oscillation is kept low. The implications for simulating the emittance feedback for the Diamond-II storage ring are also discussed.
Á. Freitas, V. Hardion, M. Lindberg, R. Lindvall, R. Svärd, C. Takahashi
MAX IV Laboratory, Lund University, Lund, Sweden
MAX IV is a fourth generation synchrotron facility at Lund, Sweden. It is composed by a full energy linear accelerator and two storage rings with 1.5 GeV and 3 GeV, which requires hundreds of beam position monitors. In this context, Libera Single Pass E and Libera Brilliance+ are employed as BPM instruments. This paper will present an overview of the control system suite used in the facility, including the communication, data acquisition and storage pipelines, monitoring, configuration and software maintainability.
