Neural Network Inverse Models for Implicit Optics Tuning in the AGS to RHIC Transfer Line
327
J.P. Edelen, N.M. Cook, J.A. Einstein-Curtis
RadiaSoft LLC, Boulder, Colorado, USA
K.A. Brown, V. Schoefer
BNL, Upton, New York, USA
Funding:This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under Award Number DE-SC0019682 One of the fundamental challenges of using machine-learning-based inverse models for optics tuning in accelerators, particularly transfer lines, is the degenerate nature of the magnet settings and beam envelope functions. Moreover, it is challenging, if not impossible, to train a neural network to compute correct quadrupole settings from a given set of measurements due to the limited number of diagnostics available in operational beamlines. However, models that relate BPM readings to corrector settings are more forgiving, and have seen significant success as a benchmark for machine learning inverse models. We recently demonstrated that when comparing predicted corrector settings to actual corrector settings from a BPM inverse model, the model error can be related to errors in quadrupole settings. In this paper, we expand on that effort by incorporating inverse model errors as an optimization tool to correct for optics errors in a beamline. We present a toy model using a FODO lattice and then demonstrate the use of this technique for optics corrections in the AGS to RHIC transfer line at BNL.
L. Torino, G. Benedetti, F.F.B. Fernández, U. Iriso, Z. Martí, J. Moldes, D. Yépez
ALBA-CELLS, Cerdanyola del Vallès, Spain
The polarization of the synchrotron radiation produced by a bending magnet can be selected by properly choosing the vertical emission angle. At beamlines this can be done by moving a slit to cut out unwanted polarization: this method is time consuming and not very reproducible. Another option is to fix the slit position and generate a local bump with the electron beam, and vary the emission angle at the source point such that the slit is illuminated with the desired polarization. At ALBA, we have implemented this option within the Fast Orbit Feedback, which allows to perform the angle switch in less than one minute without affecting the other beamlines. This report describes the implementation of this technique for the dipole beamline MISTRAL at the ALBA Synchrotron.
Multi-Dimensional Feedforward Controller at MAX IV
335
C. Takahashi, Á. 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.
R. Broucquart, N. Hubert
SOLEIL, Gif-sur-Yvette, France
In the framework of the SOLEIL II project, the diagnostics group must anticipate ahead of the dark period the upgrade of important system like the BPM electronics, the timing system end the Fast Orbit Feedback (FOFB). The FOFB is a complex system that is currently embedded in the BPM electronics modules (eBPM). A new flexible stand-alone platform is under conception to follow the future upgrades of surrounding equipment, and to allow the integration of future correction schemes. In this paper we will present the current status of technical decisions, tests and developments.
Requirements and Design for the PETRA IV Fast Orbit Feedback System
343
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
Beam Stability Requirements for Ultra-Low Emittance Circular Light Sources
G.M. Wang
BNL, Upton, New York, USA
For many light sources undergoing upgrades to 4th generation facilities, the breadth and importance of beam stability has grown substantially i.e. tighter stability requirements over greater bandwidths over various timescales. Diagnostics groups now require significant knowledge of beam stability requirements, sources of disturbances (ground motion, thermal expansion, water cooling, power supplies), their measurement (accelerometers, FEA, experimental modal analysis, transfer functions) and mitigation (passive damping, feedback or stabilisation techniques/reference monitoring like hydrostatic levelling or length encoders on reference columns etc). A more holistic approach of beam stability is becoming more common, considering electron BPMs, front-end XBPMs and beamline XBPMs together and enabling synchronised review of stability data from fast archivers.
please see instructions how to view/control embeded videos
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.
please see instructions how to view/control embeded videos
Adaptive Feedforward Control of Closed Orbit Distortion Caused by Fast Helicity-Switching Undulators
374
M. Masaki, H. Dewa, T. Fujita, H. Maesaka, K. Soutome, T. Sugimoto, S. Takano, M.T. Takeuchi, T. Watanabe
JASRI, Hyogo, Japan
T. Fukui, H. Maesaka
RIKEN SPring-8 Center, Innovative Light Sources Division, Hyogo, Japan
K. Kubota
SES, Hyogo-pref., Japan
K. Soutome, T. Sugimoto, S. Takano, H. Tanaka, T. Watanabe
RIKEN SPring-8 Center, Hyogo, Japan
We developed a new correction algorithm for closed orbit distortion (COD) based on adaptive feedforward control (AFC). The AFC system effectively works for the suppression of the fast COD due to known error sources with repetitive patterns such as helicity-switching undulators. The scheme aims to counteract error sources by feedforward correctors at the position or in the vicinity of error sources so that a potential risk of unwanted local orbit bumps, which is known to exist for the global orbit feedback, can be eliminated in a reliable and accurate manner. This option is especially advantageous when an error source causes an angular distortion of photon beams such as a fast orbit distortion near undulators. Thus, the AFC provides a complementary capability to a so-called fast global orbit feedback (FOFB) for coming next-generation light sources where ultimate light source stability is essentially demanded. In this talk, introduction to the AFC, its theoretical aspect and advantages, the system overview, the experimental results for the effects of AFC will be presented. M. Masaki, et al., J. Synchrotron Rad. 28, 1758-1768 (2021).
please see instructions how to view/control embeded videos
Operational and Beam Study Results of Measurements with the Transverse Feedback System at the Canadian Light Source
481
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.
Orbit Correction Upgrade at the Canadian Light Source
485
T. Batten, M. Bree, J.M. Vogt
CLS, Saskatoon, Saskatchewan, Canada
The Canadian Light Source is a 3rd generation synchrotron that began user operations in 2005 and now supports 22 operational beamlines. The orbit correction system was upgraded in 2021 to improve machine reliability and performance. This upgrade has also increased the diagnostic capabilities and supports easy integration of new functionality, providing the foundation for future enhancements.
Design and Status of Fast Orbit Feedback System at SOLARIS
G.W. Kowalski, K. Gula, R. Panaś, A.I. Wawrzyniak, J.J. Wiechecki
NSRC SOLARIS, Kraków, Poland
SOLARIS storage ring has been built with basic set of diagnostic and feedback systems. FOFB system, as much more advanced and not as critical for startup was envisioned as later addition to the design. Now, we are in the process of implementing this addition. The system’s workhorse is Instrumentation Technologies Libera Brilliance+ with its Fast Acquisition data path and customizable FPGA modules. Feedback algorithm running in hardware provides fast calculations and direct communication with fast power supplies. The hardware installation is almost finished with configuration and software works running in parallel. First measurements of response matrix and proof-of-concept tests were performed.
Conceptual Design of the Transverse Multi-Bunch Feedback for the Synchrotron Radiation Source PETRA IV
488
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.
Measurements for Emittance Feedback based on Resonant Excitation at Diamond Light Source
492
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.
Experimental Demonstration of Optical Stochastic Cooling: Single-Particle Feedback in the Optical Regime
J.D. Jarvis
Fermilab, Batavia, Illinois, USA
Funding:This work was supported by the U.S. Department of Energy under contract No. DE-AC02-07CH11359 The first realization of stochastic cooling in the optical regime was recently achieved at Fermilab’s Integrable Optics Test Accelerator (IOTA) storage ring using the transit-time method of Optical Stochastic Cooling (OSC). OSC uses free-space electromagnetic waves as the signaling medium, pickup and kicker undulators to couple the radiation to the circulating particle beam, and optical amplifiers for signal amplification. Stable cooling was successfully demonstrated in one, two and three dimensions and OSC experiments were performed with a single electron stored in IOTA. The total cooling force in these non-amplified OSC experiments was approximately an order-of-magnitude larger than the natural longitudinal synchrotron-radiation damping. These achievements required precise alignment and femto-second accuracy of the particles with their respective undulator-radiation pulses along with a wide range of technical and diagnostic elements. We describe the integrated OSC system, its performance and comparison to theoretical expectations, and our OSC R&D program that includes advanced concepts in beam cooling and control.
please see instructions how to view/control embeded videos
