SwissFEL LLRF system was well designed with precise RF detection, reliable amplitude and phase feedback, and high degree automation. After the start of user operation, new requirements on robustness and reproducibility have been raised for LLRF. Efforts have been spent to consolidate the LLRF system. We implemented lookup-table-based algorithms for the fast setup of klystrons for desired...
ATLAS, the world’s first accelerator to use RF superconductivity for ion acceleration has undergone a major upgrade to increase the beam transmission efficiency and intensity. A first of its kind, the new CW RF quadrupole (RFQ) was built to replace three superconducting (SC) resonators (β=0.008 and 0.016). In addition, a new cryomodule of seven 72.75 MHz (β=0.077) SC quarter-wave resonators...
For the SLS-2 project and the 500 MHz RF upgrades, the LLRF will be renewed and the previously analog system is going to be replaced by a digital one. The new system is built into two separated chassis, an analog frontend and a CompactPCI Serial based digital backend interconnected with coaxial cables. The custom design analog frontend implements two up- and eight down-conversion channels 50...
At PSI, the high intensity proton accelerator (HIPA) delivers a proton beam of 590 MeV energy at a current of up to 2.4 mA. The RF cavities are operated in CW mode at a frequency of 50 MHz. The initial system was built about 30 years ago with the technology at that time which was predominantly analogue. With the modern replacement of the analogue system, the cavity operation and maintenance...
CompactPCI Serial has been selected as one of the Next Processing Platforms (NPP) for development of future electronic systems at PSI. In this contribution, we describe the new platform and the pilot application for the Swiss Light Source (SLS) LLRF upgrade. We detail Hardware/Firmware/Software architectures, present automated testing procedures, as well as share the hands-on experience gained...
A new 16 channel LLRF front end was developed at PSI for the two X-band RF stations at SwissFEL.
This poster summarizes operational experience and performance achieved with new direct up-conversion LLRF front end. In addition, comparison between the dual conversion to the new direct conversion front end is given.
ALBA is a 3rd generation synchrotron light source located in Cerdanyola del Vallès (Barcelona, Spain). The facility comprises a 3 GeV electron storage ring (SR), injected from a 110 MeV Linac through a full energy booster synchrotron. The RF system consists of six normal conducting cavities in the storage ring, fed with IOT based transmitters that are able to provide up to 3 MV to the...
Originally, the LLRF control software, developed for the accelerators at DESY (XFEL, FLASH,...), was exclusively based on DOOCS. The development of the ChimeraTK framework enables the LLRF control applications to use other control systems than DOOCS (i.e. EPICS, OPC-UA), as well. Recently, EPICS-based LLRF control applications have been implemented at LLRF control systems outside of...
The two cyclotrons at the High Intensity Proton Accelerator (HIPA) at PSI are equipped with eight high-power CW RF cavities at 50 MHz and one flat-top cavity at 150 MHz with input power levels up to 500 kW.
The purpose of the startup sequencer is to establish continuous (CW) high power RF operation as safe, fast and reliable as possible from both cold and warm cavity initial states. Precise...
The Canadian Light Source, at the University of Saskatchewan, is a 3rd generation synchrotron light source located in the city of Saskatoon, Canada. The facility comprises a 250 MeV LINAC, a full energy booster and a 2.9 GeV storage ring. The radiofrequency system in the booster consist of two 5-cell cavities feed with a single SSPA. The analogue LLRF for the booster has been recently replaced...
CNAO is one of the six hadrontherapy centers able to treat cancer with proton beams and carbon ions. It is a synchrotron with a diameter of 77 meters, equipped with a LINAC as the injector. The stability of the RF in the LINAC being fundamental for the quality of the beam injected into the ring impelled CNAO to decide to upgrade the actual analogic LINAC LLRF to a digital one.
This...
The ISIS synchrotron routinely uses a dual harmonic RF system to accelerate beam currents in excess of 230 µA to two target stations. Commissioning of a new PXI-based LLRF system was reported at the LLRF’19 workshop. Since then, the system has been deployed for all ISIS user cycles. Further developments include using the IQ loop error signals for RF cavity tuning and we plan to extend this...
Recently the test of superconducting cavities and the cryomodules of the low energy linear accelerator part (SCL3) of a heavy ion accelerator, RAON are have been finished. They are installed and the preparation process for the commissioning is ongoing in Daejeon, Korea by Rare Isotope Science Project (RISP) team in Institute of Basic Science (IBS). The purpose of this accelerator are the...
The J-PARC Main Ring (MR) has achieved the delivery of the 30 GeV proton beam with the beam power of 515 kW to the neutrino experiment as of April 2021.
The Longitudinal coupled bunch instabilities (CBI) has been observed above 450 kW operation due to the cavity impedance.
To mitigate the CBI, we designed the prototype modules of the low-level-rf (LLRF) system based on the MTCA.4 platform....
For the new PETRA IV project at DESY a new LLRF system based on MicroTCA.4 is foreseen. It will be used to control 24 cavities at 500MHz and 24 cavities at 1.5GHz. In this contribution we will present the setup of a first prototype of the LLRF system for the single cavity LLRF system operating at 500MHz continuous wave.
There are many stages in the LLRF and RF system development process for any new accelerator that can take advantage of hardware emulation of the high power RF system and RF cavities. LLRF development, bench testing, control system development and testing of installed systems must happen well before SRF cavities are available for test. The PIP-II Linac has three frequencies of SRF cavities,...
The first version of digital low level RF (DLLRF) for the Diamond Light Source storage ring and booster was developed with ALBA Synchrotron. Six systems have been built so far. Two of them are in routine operation controlling two normal conducting HOM-damped cavities in the Diamond storage ring. A third system is being used for cavity testing in the RF test facility. The fourth system is...
The FLASH facility is currently re-commissioned after an almost 10-month shutdown for the FLASH2020+ project. Within this period several subsystems of the machine have been renovated or completely rebuild. One of the major tasks was the exchange of the accelerating modules ACC2 and ACC3 to European XFEL type cryomodules. Furthermore, the master oscillator which successfully operated for 15...
In the Super Proton Synchrotron (SPS) during multi batch injection, we must distinguish between bunches that have been circulating in the machine, and newly injected bunches. This required a new Low Level RF (LLRF) module to measure phase of the individual bunches that are circulating in the machine. Individual bunch measurement is also needed to properly operate two phase loops during ion...
Accelerator low-level RF (LLRF) systems have demanding requirements on signal distribution circuity. The RF feedback control paths from the cavity are not corrected for error and demand a high level of attention to performance. This chassis allows the frequency dependent (805 MHz or 201.25 MHz) circuits to be separated from the modular frequency independent digital low level RF system. The...
During the last few years, the LLRF systems of all CERN small synchrotrons (PSB, LEIR, AD, ELENA) have been upgraded to a fixed frequency clock scheme. As a result, the beam profiles obtained from the digitization of pick-up signals will have a different number of samples as the revolution frequency varies. In this work, we present a method to reconstruct the time-domain signal of the bunch...
The SLAC National Accelerator Laboratory has completed the installation and checkout of hardware for the SRF based accelerator LCLS-II, an ultra-bright Free Electron Laser. The LCLS-II is composed of 296 SRF cavities, each with its own LLRF control system. During production, care was taken to preserve the low noise design performance needed for controlling the 5x107 QL SRF cavities. A novel...
Commissioning of the LLRF systems of CERN accelerators consists of a number of time-consuming procedures, involving calibration and fine-tuning of numerous parameters. In the recent years, a system of Python scripts was developed to automate the setting up of the LLRF of the LHC and the SPS. Targeted at RF experts, the scripts provide high-level interface to the underlying physical system,...
Polish Free Electron Laser PolFEL is a new facility located in the National Centre for Nuclear Research in Swierk (Otwock, Poland). PolFEL will be based on the 200 MeV linear superconducting electron accelerator made of the TESLA type cavities, targeting VUV, IR and THZ wavelengths. The accelerator will operate in the single cavity regulation mode using solid state amplifiers. It will be able...
The goal of a LLRF system is to control an actual RF cavity with beam. While digital simulations have a place, having an analog circuit to stand in for the cavity can be tremendously helpful in validating hardware+firmware+software under development. A wide range of cavity emulators have been developed in collaboration with SLAC, and LBNL. Cavity emulators are typically based on quartz...
The Fermilab 650 STC (Spoke resonator Test Cave) is used as a horizontal test facility for the PIP-II 650 MHz Low Beta(LB) and HB superconducting cavities provided by INFN(Italy) and RRCAT(India). The cavities are 5-cell elliptical doublet type with betas of 0.61 and 0.9.Testing of two HB cavities has been completed and testing with a LB cavity is in progress. Coupler thermal testing, tuner...
The Fermilab 650 MHz Cryomodule Test Stand is a facility for independently testing HB/LB 650 MHz and SSR2 (325 MHz) cryomodules without beam. The first cryomodule tested will be the HB 650 which consists of six cavities. The LLRF system is built with the same LLRF controller as the LCLS-II project with mostly identical firmware and software components allowing for the small differences in...
Sampling the RF signals is a challenging problem for the modern LLRF Control System. One of the analog-to-the digital conversion problems is the clock jitter's influence on the output signal. As clock jitter impact increases with the input signal frequency, it is primarily a problem in precise RF systems, where signal frequencies are high. This issue can be minimized by lowering the input...
The Korean 4th Generation Storage Ring (4GSR) project is being under construction with the plan of commissioning at the end of 2027. The beam energy of this facility is 4 GeV, and a 500 MHz EU- HOM-damped normal cavity will be adopted to generate the ultra-low emittance beam of 58 pm rad with the beam current of 400 mA. This paper covers the design considerations of the low level RF (LLRF)...
An essential requirement for ESS is to assure a precise phase synchronization of LLRF and Beam Diagnostics systems, operating at 352.21 MHz and 704.42 MHz. The long-term required phase accuracy is 0.1° between adjacent outputs and 2.0° between any two points.
The phase synchronization system consists mainly of a Master Oscillator (MO) in the Klystron Gallery and a Phase Reference Line (PRL)...
Though XFEL(X-ray Free Electron Laser) machines can produce X-ray pulses over 100 million times brighter than storage-ring-based machines, the XFEL machines have very limited beamlines of 1~3. PAL-XFEL machine includes one hard and one soft X-ray beamlines, but only one beamline can be serviced at each shift period. Efforts to operate the beamlines of PAL-XFEL simultaneously have been made in...
In the framework of the BESSY-VSR upgrade, the beam injection from the booster to the storage ring has to be modified in order to inject shorter bunches. For this purpose, a new PETRA-type 5 cell cavity has been installed in the booster ring and a second one is to be installed. These two new normal conducting 500MHz cavities are to be powered by two already installed and tested 80kW Solid...
REGAE is a facility for UED experiments (ultrafast electron diffraction) based on a normal conducting S-band gun and buncher cavity. Their RF regulation is performed by a single cavity controller, implemented by an FPGA firmware and operating at 125 MHz. With a variant of the Struck SIS8300-KU controller board that is equipped with 250 MSps ADCs we were able to increase the frequency of the...
A new powerful longitudinal diagnostics system is being developed for the two CERN’s antiproton machines, the Antiproton Decelerator (AD) and the Extra Low Energy Antiproton ring (ELENA).
The system is based upon a fast computer, fully integrated in CERN’s controls infrastructure, with high processing power and hosting a Linux server running real-time software for online data analysis. Its...
The LLRF system for the ESS proton linac also comprises a piezo driver subsystem responsible for the fine superconducting cavity tuning. The DMCS tailored the design of this device to the specific needs of the elliptical (M-Beta and H-Beta) resonators and the spoke structures, too. This device provides two independent channels to control piezo voltage signals. It can generate either unipolar...
The PolFEL is a Polish Free-Electron Laser project under construction at National Centre for Nuclear Research in Świerk. An essential requirement for the PolFEL is to assure a precise phase synchronization of LLRF and Beam Diagnostics systems operating at 1300 MHz.
The synchronization system consists of a phase synchronization system and the timing system. The phase synchronization system...
The front end of Los Alamos Neutron Science Center (LANSCE) linear accelerator (linac) uses four 201.25-MHz Drift-Tube Linac (DTL) modules to accelerate the H+ and H- beams to 100 MeV. Three of the 201.25-MHz DTL tanks, Modules 2, 3, and 4, are powered by diacrodes and the first DTL tank, module 1, is powered by a tetrode. A 20-kW solid-state power amplifier (SSPA) is used to provide 15 kW of...
The Sirepo platform is designed to offer GUIs for popular simulation codes used in the accelerator space, along with integration with a JupyterLab Python environment. This includes srw, radia, elegant, and warp, mad-x, opal, and synergia, as well as ongoing development for an online controls and fault detection interface. This open-source platform is available through sirepo.com, as well as a...
The linear accelerator (LINAC) at the Los Alamos Neutron Science Center (LANSCE) consists of Pre-buncher, Main-Buncher, low-energy beam transport (LEBT), four 201.25-MHz Drift Tube Linacs (DTLs) and forty-four 805-MHz Coupled Cavity Linacs(CCLs). As a part of the upcoming LANSCE Modernization project, low-level RF (LLRF) systems of four 201-MHz DTLs and twenty-six 805-MHz SCLs are digitized....
LCLS-II is currently in its commissioning phase at SLAC. It is an X-ray FEL driven by a CW superconducting LINAC. The beam injector plays a crucial role in the overall performance of the accelerator, and is critical to the final electron beam performance parameters. The LCLS-II injector comprises of a 185.7 MHz VHF copper gun cavity, and a 1.3 GHz two-cell L-band copper buncher cavity. The...
The superconducting cavity vertical test stand at DESY is going to be updated with the MTCA.4 based system. The digital self exited loop (SEL) LLRF controller has been developed to fulfill the requirements for the controller to drive the cavity with high QL up to 1e10 and high cavity detuning up to 10kHz. In order to test the SEL controller, additionally the real-time cavity simulator has been...
The Facility for Rare Isotope Beams (FRIB) opened for full user operation in May 2022 and is currently prototyping a 644 MHz superconducting (SC) cavity and cryomodule for an energy upgrade of the accelerator to 400 MeV/u. The low level radio frequency (LLRF) controllers in operation are based on Xilinx Spartan 6 field programmable gate array (FPGA) and support frequencies up to 322 MHz. With...
The preparation of the LLRF Control equipment of the SeaLab project for the commissioning is going on. The current hardware configuration comprises gun and booster cavities under server PC control and the standalone transverse deflecting cavity controller. The ongoing infrastructure works, i.e. cabling traces termination/patch panels connection, network installation and power lines...
The High Repetition rate Electron Scattering (HiRES) accelerator at LBNL uses a CW, normal-conducting RF electron gun and bunching cavity to deliver high-stability, high repetition rate electron pulses for scientific applications, such as ultrafast electron diffraction (UED) and FELs. Beyond-state-of-art stability is required for the electron beam energy in order to achieve femtosecond...
TRIUMF ISAC 1 tuning controllers operate using minimum seeking sliding mode controller to minimize the reflected power in their cavities. As with all minimum seeking algorithms, chatter present in the controller can degrade its performance and cause necessary mechanical wear. By observing the rate at which the minimizing function approaches the sliding surface, it is possible to determine...
Compact particle accelerators are increasingly needed in medical, industrial, and defense settings. Such an accelerator requires a highly efficient, lightweight, and space-efficient footprint; this leverages particularly unique requirements on RF, power, and thermal budgets. RadiaSoft has been working with SLAC on developing the LLRF system for a structure consisting of 26 pairs of...
LCLS-II is an X-Ray Free Electron Laser (XFEL) com-
missioned in 2022, being the first Continuous Wave (CW)
hard XFEL in the world to come into operation. To accel-
erate the electron beam to an energy of 4 GeV, 280 TESLA
type superconducting RF (SRF) cavities are used. A Loaded
Q (𝑄𝐿 ) of 4×10^7 is used to drive the cavities at a power level
of a few kilowatts. For this 𝑄𝐿 , the RF...
Author:
James Latshaw
PIP-II Resonance Control System
J. Latshaw, B. Chase, C. Hovater, R. Bachimanchi, T. Plawski,
Thomas Jefferson National Accelerator Facility,
Newport News, VA 23606, USA
June 30, 2022
Abstract
The PIP-II Resonance Control System has the goal of providing the electronics to mechanically tune four superconducting cavities as directed by two RF control stations...
The stability and convergence of an Iterative Learning Controller (ILC) may be assessed in time domain, by actually iterating the equations for a variety of inputs, or by finding the eigenvalues (lambda) of the iterated system (lambda-domain), or by forming the Z-transform and applying analogues of the Nyquist criteria. Two often-used criteria are (i) Asymptotic Convergence (AC) of the...
The Canadian Light Source (CLS) operates a single-cell CESR-B superconducting RF cavity system in the 2.9 GeV storage ring, powered by a 310 kW klystron. After the successful implementation of ALBA’s digital low-level radio frequency system (DLLRF) in the dual cavity booster ring at CLS, plans are in place to test the same system in the storage ring RF. The DLLRF also leaves open future...
The Electron-Ion Collider (EIC), to be constructed at Brookhaven National Laboratory (BNL), is a roughly 10 year project to design and construct a facility to collide high energy polarized electron beams with polarized proton and heavy ion beams at center of mass energies from 20 GeV to 140 GeV and luminosity up to 1034 cm-2s-1. The project is a partnership between BNL and the Thomas Jefferson...
The Electron-Ion Collider (EIC), to be constructed at Brookhaven National Laboratory (BNL), is a roughly 10 year project to design and construct a facility to collide polarized high energy electron beams with polarized proton and heavy ion beams at center of mass energies from 20 GeV to 140 GeV and luminosity up to 1034 cm-2s-1. The project is a partnership between BNL and the Thomas...
Medaustron is a cancer treatment facility with ion therapy. It is based on a synchrotron accelerator with proton and carbon beams. The treatment has been successfully running since 2016, treating about 400 patients a year. Even at this young age of the facility, though, there are problems arising regarding the sustainability of the current system as some of the components are nearing end of...
