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Karlsruhe Research Accelerator (KARA) at the Karlsruhe Institute of Technology (KIT) is an electron storage ring and synchrotron radiation facility. The operation at KARA can be very flexible in terms of beam energy, optics, intensity, filling structure, and operation duration. For different aspects of the operation of the accelerator separate and individual simulation models are in place using different simulation tools, custom lattice data and varying levels of maintenance. In a general push at the accelerator to provide unified access via Python, a new framework was implemented using Ocelot with a much closer integration to the accelerator control system and supplementary tools. This allows a better integration and lowers the effort necessary for simulations and predictions of actual changes to the beam properties based on live data. It also provides a good entry point for the various Python based machine learning activities at the accelerator and the goal to obtain an easier to maintain and test accelerator model. This paper presents the taken approach and current status of this project., Proceedings of the 13th International Workshop on Emerging Technologies and Scientific Facilities Controls, PCaPAC2022, Dolní Brežany, Czech Republic

The particle accelerators hosted at the Institute for Beam Physics and Technology (IBPT) represent a complex infrastructure with a live control system interface, a data archive, measurement routines and storage and management of metadata, among other aspects. The ’IBPT Python tools’ were created to provide a unified interface to all aspects of the accelerator infrastructure for both short-term student projects and basic accelerator operations. Instead of creating another custom framework, these sets of tools focus on bridging the gap between well established libraries and our facility and accelerator specific needs. External and accelerator specific libraries are glued together to provide an interface in order to minimize the technical knowledge of the accelerator infrastructure needed by the end user. Well established software engineering workflows of continuous integration were implemented to provide automatic testing, packaging, API documentation and release management. This paper discusses the general motivation and approach taken to create and maintain such a set of Python modules., Proceedings of the 13th International Workshop on Emerging Technologies and Scientific Facilities Controls, PCaPAC2022, Dolní Brežany, Czech Republic

The Karlsruhe Research Accelerator (KARA) at the Karlsruhe Institute of Technology (KIT) is an electron storage ring and synchrotron radiation facility. The operation at KARA can be very flexible in terms of beam energy, optics, intensity, filling structure, and operation duration. Multiple digital LLRF systems are in place to control the complex dynamics of the RF cavities required to keep the electron beam stable. Each LLRF system represents a well established closed system with its own set of control logic, state machine and feedback loops. This requires additional control logic to operate all stations together. In addition, during special operation modes at KARA, extra features such as well defined beam excitation are needed. This paper presents the implementation of a Python layer created to accommodate the complex set of options as well as an easy to use interface for the operator and the general control system., Proceedings of the 13th International Workshop on Emerging Technologies and Scientific Facilities Controls, PCaPAC2022, Dolní Brežany, Czech Republic

The linear accelerator FLUTE (Far Infrared Linac and Test Experiment) at KIT serves as a test facility for accelerator research and for the generation of ultra-intense coherent THz radiation. To achieve stable THz photon energy and optimal beam trajectory, the energy of the electrons emitted from the RF photo-injector must be stable. The accelerating voltage of the RF cavity has been shown to be a significant influencing factor. Here, we report on the development of a slow closed-loop feedback system to stabilize the RF power and thus the accelerating voltage in the RF photo-injector cavity. With this closed-loop feedback system the relative standard deviation of the RF power in the cavity can be improved by 8.5 %., Proceedings of the 13th International Particle Accelerator Conference, IPAC2022, Bangkok, Thailand

For the development of future synchrotron light sources new operation modes often have to be considered. One such mode is the operation with a negative momentum compaction factor to provide the possibility of increased dynamic aperture. For successful application in future light sources, the influence of this mode has to be investigated. At the KIT storage ring KARA (Karlsruhe Research Accelerator), operation with negative momentum compaction has been implemented and the dynamics can now be investigated. Using a variety of high-performance beam diagnostics devices it is possible to observe the beam dynamics under negative momentum compaction conditions. This contribution presents different aspects of the results of these investigations in the longitudinal and transversal plane., Proceedings of the 13th International Particle Accelerator Conference, IPAC2022, Bangkok, Thailand

In the framework of the compact STorage ring for Accelerator Research and Technology (cSTART) project, which will be realized at Karlsruhe Institute of Technology (KIT), a Very Large Acceptance compact Storage Ring (VLA-cSR) is planned to study the injection and the storage of 50 MeV, ultra-short (sub-ps) electron bunches from a laser plasma accelerator (LPA) and the linac-based test facility FLUTE. For such a storage ring, where a single bunch with a relatively wide range of bunch charge (1 pC - 1000 pC ) and energy spread (10’4 - 10’2) will circulate at a relatively high revolution frequency (7 MHz), the choice of beam diagnostics is very delicate. In this paper, we would like to discuss several beam diagnostics options for the storage ring and to briefly report on several tests that have been or are planned to be realized in our existing facilities., Proceedings of the 13th International Particle Accelerator Conference, IPAC2022, Bangkok, Thailand

FLUTE (Ferninfrarot Linac- Und Test-Experiment) is a compact versatile linac-based accelerator test facility at KIT. Its main goal is to serve as a platform for a variety of accelerator studies and to generate strong ultra-short THz pulses for photon science. It will also serve as an injector for a Very Large Acceptance compact Storage Ring (VLA-cSR), which will be realized at KIT in the framework of the compact STorage Ring for Accelerator Research and Technology (cSTART) project. To achieve acceleration of electrons in the RF photoinjector and LINAC (from FLUTE) with high stability, it is necessary to provide stable RF power. For this goal, an upgrade of the existing RF system design has been proposed and is currently being implemented. This contribution will report on the updated RF system design and the commissioning status of the new RF system components., Proceedings of the 13th International Particle Accelerator Conference, IPAC2022, Bangkok, Thailand

The compact STorage ring for Accelerator Research and Technology cSTART project will deliver a new KIT accelerator test facility for the application of novel acceleration techniques and diagnostics. The goal is to demonstrate storing an electron beam of a Laser Plasma Accelerator (LPA) in a compact circular accelerator for the first time. Before installing an LPA, the Far-Infrared Linac and Test Experiment (FLUTE) will serve as a full energy injector for the compact storage ring, providing stable bunches with a length down to a few femtoseconds. The transport of the bunches from FLUTE to the cSTART storage ring requires a transfer line which includes horizontal, vertical and coupled deflections which leads to coupling of the dynamics in the two transverse planes. In order to realize ultra-short bunch lengths at the end of the transport line, it relies on special optics which invokes high and negative dispersion. This contribution presents dynamic aperture studies based on six-dimensional tracking through the lattice of the transfer line., Proceedings of the 13th International Particle Accelerator Conference, IPAC2022, Bangkok, Thailand

The compact and versatile linear accelerator-based test facility FLUTE (Ferninfrarot Linac- Und Test-Experiment) is operated at KIT. Its primary goal is to serve as a platform for a variety of accelerator R\ studies like the generation of strong ultra-short terahertz pulses. The amplitude of the generated coherent THz pulses is proportional to the square number of particles in the bunch. With the transverse emittance a measure for the transverse particle density can be determined. It is therefore a vital parameter in the optimization for operation. In a systematic study, the transverse emittance of the electron beam was measured in the FLUTE injector. A detailed analysis considers different influences such as the bunch charge and compares this with particle tracking simulations carried out with ASTRA. In this contribution, the key findings of this analysis are discussed., Proceedings of the 13th International Particle Accelerator Conference, IPAC2022, Bangkok, Thailand

In the booster synchrotron of the Karlsruhe Research Accelerator (KARA), the beam is injected from the microtron at 53 MeV and ramped up to 500 MeV. Though the injected beam current from the microtron to the booster seems good, the injection efficiency into the booster is currently low due to various effects. Consequently, an upgrade of the whole beam diagnostics system is taking place in the booster, in order to improve the injection efficiency through understanding the loss mechanisms and the behavior of bunches. Among these diagnostics tools are beam loss monitors, a transverse profile monitor and a longitudinal profile monitor. In this paper, we will describe the setups used for bunch profile measurements in both transverse and longitudinal planes and report on first data analysis results., Proceedings of the 13th International Particle Accelerator Conference, IPAC2022, Bangkok, Thailand

FLUTE (Ferninfrarot Linac- Und Test-Experiment) is a compact linac-based test facility for accelerator and diagnostics R An example for a new accelerator diagnostics tool currently studied at FLUTE is the split-ring-resonator (SRR) experiment, which aims to measure the longitudinal bunch profile of fs-scale electron bunches. Laser-generated THz radiation is used to excite a high frequency oscillating electromagnetic field in the SRR. Particles passing through the SRR gap are time-dependently deflected in the vertical plane, which allows a vertical streaking of an electron bunch. This principle allows a diagnosis of the longitudinal bunch profile in the femtosecond time domain and will be tested at FLUTE. This contribution presents an overview of the SRR experiment and the results of various tracking simulations for different scenarios as a function of laser pulse length and bunch charge. Based on these results possible working points for the experiments at FLUTE will be proposed., Proceedings of the 12th International Particle Accelerator Conference, IPAC2021, Campinas, SP, Brazil

RF phase modulation at twice the synchrotron frequency can be used to split a stored electron bunch into two or more bunchlets orbiting each other. We report on time-resolved measurements at the Karlsruhe Research Accelerator (KARA), where this bunch splitting was used to increase the threshold current of the microbunching instability, happening in the short-bunch operation mode. Turning the modulation on and off reproducibly affects the sawtooth behavior of the emitted coherent synchrotron radiation., Proceedings of the 12th International Particle Accelerator Conference, IPAC2021, Campinas, SP, Brazil

Computer studies of longitudinal motion have been performed with the objective to estimate the possibility of detection of alpha-buckets at the KIT storage ring KARA (Karlsruhe Research Accelerator). The longitudinal equations of motion and the Hamiltonian were expanded to high order terms of the energy deviation of particles in a beam. Roots of third order equation for three leading terms of momentum compaction factor and free energy independent term were derived in a form suitable for analytical estimations. Averaged quadratic terms of closed orbit distortions caused by misalignment of magnetic elements in a ring lead to orbit lengthening independent of particle energy deviation. Particle transverse excursions were estimated and are taken into account. Simulations have been bench-marked on existing experiments at Metrology Light Source (MLS) in Berlin (Germany) and SOLEIL (France). Parameters of three simultaneous beams and alpha buckets at MLS and SOLEIL have been reproduced with high accuracy. A computer model of KARA was used to predict behavior and the dynamics of possible simultaneous beams in the ring., Proceedings of the 12th International Particle Accelerator Conference, IPAC2021, Campinas, SP, Brazil

Electro-optical (EO) methods are nowadays well-proven diagnostic tools, which are utilized to detect THz fields in countless experiments. The world’s first near-field EO sampling monitor at an electron storage ring was developed and installed at the KIT storage ring KARA (Karlsruhe Research Accelerator) and optimized to detect longitudinal bunch profiles. This experiment with other diagnostic techniques builds a distributed, synchronized sensor network to gain comprehensive data about the phase-space of electron bunches as well as the produced coherent synchrotron radiation (CSR). These measurements facilitate studies of physical conditions to provide, at the end, intense and stable CSR in the THz range. At KIT, we also operate FLUTE (Ferninfrarot Linac- und Test-Experiment), a new compact versatile linear accelerator as a test facility for novel techniques and diagnostics. There, EO diagnostics will be implemented to open up possibilities to evaluate and compare new techniques for longitudinal bunch diagnostics. In this contribution, we will give an overview of results achieved, the current status of the EO diagnostic setups at KARA and FLUTE and discuss future prospects., Proceedings of the 12th International Particle Accelerator Conference, IPAC2021, Campinas, SP, Brazil

A very large acceptance compact storage ring (VLA-cSR) is under design at the Institute for Beam Physics and Technology (IBPT) of the Karlsruhe Institute of Technology (KIT, Germany). The combination of a compact storage ring and a laser wakefield accelerator (LWFA) might be the basis for future compact light sources and advancing user facilities. Meanwhile, the post-LWFA beam should be adapted for storage and accumulation in a dedicated storage ring. Modified geometry and lattice of a VLA-cSR operating at 50 MeV energy range have been studied in detailed simulations. The main features of a new model are described here. The new design, based on 45° bending magnets, is suitable to store the post-LWFA beam with a wide momentum spread (1% to 2%) as well as ultra-short electron bunches in the fs range from the Ferninfrarot Linac- Und Test- Experiment (FLUTE). The DBA-FDF lattice with relaxed settings, split elements, and higher-order optics of tolerable strength allows improving the dynamic aperture to an acceptable level. This contribution discusses the lattice features in detail and different possible operation schemes of a VLA-cSR., Proceedings of the 12th International Particle Accelerator Conference, IPAC2021, Campinas, SP, Brazil

FLUTE (Ferninfrarot Linac- und Test-Experiment) is a compact linac-based test facility for accelerator R and source of intense THz radiation for photon science. In preparation for the next experiments, the electron beam of the injector section of FLUTE has been characterized. In systematic studies the electron beam parameters, e.g., beam energy and emittance, are measured with several diagnostic systems. This knowledge allows the establishment of different operation settings and the optimization of electron beam parameters for future experiments., Proceedings of the 12th International Particle Accelerator Conference, IPAC2021, Campinas, SP, Brazil

The Ferninfrarot Linac- Und Test-Experiment (FLUTE) is a KIT-operated linac-based test facility for accelerator research and development as well as a compact, ultra-broadband and short-pulse terahertz (THz) source. As a key component of FLUTE, the bunch compressor (chicane) consisting of four specially designed dipoles will be used to compress the 40-50 MeV electron bunches after the linac down to single fs bunch length. The maximum vertical magnetic field of the dipoles reach 0.22 T, with an effective length of 200 mm. The good field region is ±40 mm and ±10.5 mm in the horizontal and vertical direction, respectively. The latest measurement results of the dipoles in terms of field homogeneity, excitation and field reproducibility within the good field regions will be reported, which meet the predefined specifications. The measured 3D magnetic field distributions have been used to perform beam dynamics simulations of the bunch compressor. Effects of the real field properties on the beam dynamics, which are different from that of the ASTRA built-in dipole field, will be discussed., Proceedings of the 12th International Particle Accelerator Conference, IPAC2021, Campinas, SP, Brazil

In its short-bunch operation mode, the KIT storage ring KARA provides picosecond-long electron bunches, which emit coherent synchrotron radiation (CSR) up to the terahertz frequency range. Due to the high spatial compression under these conditions, the self-interaction of the bunch with its own emitted CSR induces a wake-field, which significantly influences the longitudinal charge distribution. Above a given threshold current, this leads to the formation of dynamically evolving micro-structures within the bunch and is thus called micro-bunching instability. As CSR is emitted at wavelengths corresponding to the spatial dimension of the emitter, these small structures lead to an increased emission of CSR at higher frequencies. The instability is therefore deliberately induced at KARA to provide intense THz radiation to dedicated experiments. To further increase the emitted power in the desired frequency range, we consider the potential of RF amplitude modulations to intentionally excite this form of micro-bunching in short electron bunches. This work is supported by the BMBF project 05K19VKC TiMo (Federal Ministry of Education and Research)., Proceedings of the 12th International Particle Accelerator Conference, IPAC2021, Campinas, SP, Brazil

New operation modes are often considered during the development of new synchrotron light sources. An understanding of the effects involved is inevitable for a successful operation of these schemes. At the KIT storage ring KARA (Karlsruhe Research Accelerator), new modes can be implemented and tested at various energies, employing a variety of performant beam diagnostics devices. Negative momentum compaction optics at various energies have been established. Also, the influence of a negative momentum compaction factor on different effects has been investigated. This contribution comprises a short report on the status of the implementation of a negative momentum compaction optics at KARA. Additionally, first measurements of the changes to the current-dependent bunch length will be presented., Proceedings of the 12th International Particle Accelerator Conference, IPAC2021, Campinas, SP, Brazil

During the operation of an electron synchrotron with short electron bunches, the beam dynamics are influenced by the occurrence of the micro-bunching instability. This collective instability is caused by the self-interaction of a short electron bunch with its own emitted coherent synchrotron radiation (CSR). Above a certain threshold bunch current dynamic micro-structures start to occur on the longitudinal phase space density. The resulting dynamics depend on various parameters and were previously investigated in relation to, amongst others, the momentum compaction factor and the acceleration voltage. In this contribution, the influence of the energy of the electrons on the dynamics of the micro-bunching instability is studied based on measurements at the KIT storage ring KARA (Karlsruhe Research Accelerator)., Proceedings of the 12th International Particle Accelerator Conference, IPAC2021, Campinas, SP, Brazil

The KIT storage ring KARA operates in a wide energy range from 0.5 to 2.5 GeV. Different operation modes have been implemented at KARA, so far, the double-bend achromat (DBA) lattice with non-dispersive straight sections, the theoretical minimum emittance (TME) lattice with distributed dispersion, different versions of low-compaction factor optics with highly stretched dispersion function. Short bunches of a few ps pulse width are available at KARA. Low-alpha optics has been simulated, tested and implemented in a wide operational range of the storage ring and is now routinely used at 1.3 GeV for studies of beam bursting effects caused by coherent synchrotron radiation in the THz frequency range. Different non-linear effects, in particular residual high-order components of the magnetic field, generated in high-field superconducting wigglers have been studied and cured. Based on good agreement between computer simulations and experiments, a new operation mode at high vertical tune was implemented. The beam performance during user operation as well as at low-alpha regimes has been improved. A specific optic with negative compaction factor was simulated, tested and is in operation., Proceedings of the 12th International Particle Accelerator Conference, IPAC2021, Campinas, SP, Brazil

For future synchrotron light sources different operation modes are of interest. Therefore various modes are currently being tested at the Karlsruhe Research Accelerator (KARA) including optics for a negative momentum compaction factor. These optics have been calculated and are under commissioning at KARA. Additionally, studies about expected collective effects in this regime are being performed, including the head-tail and microbunching instabilities. In this contribution we will present the status of operation in the negative momentum compaction regime and discuss expected collective effects that will be studied in this context., CERN Yellow Reports: Conference Proceedings, Vol. 9 (2020): Proceedings of the ICFA mini-Workshop on Mitigation of Coherent Beam Instabilities in Particle Accelerators, Zermatt, Switzerland, 23–27 September 2019

With the deployment of a storage spaces direct hyper-converged cluster in 2018, the whole control system server and network infrastructure of the Karlsruhe Research Accelerator have been virtualized to improve the control system availability. The cluster with 6 Dell PowerEdge R740Xd servers with 1.152 GB RAM, 72 cores and 40 TByte hyperconverged storage operates in total 120 virtual machines. We will report on our experiences running EPICS IOCs and the industrial control system WinCC OA in this virtual environment., Proceedings of the 17th International Conference on Accelerator and Large Experimental Physics Control Systems, ICALEPCS2019, New York, NY, USA

For future synchrotron light source development novel operation modes are under investigation. At the Karlsruhe Research Accelerator (KARA) an optics with negative momentum compaction has been proposed, which is currently under commissioning. In this context, the collective effects expected in this regime are studied with an initial focus on the head-tail instability and the micro-bunching instability resulting from CSR self-interaction. In this contribution, we will present the proposed optics and the status of implementation for operation in the negative momentum compaction regime as well as a preliminary discussion of expected collective effects., Proceedings of the 10th Int. Particle Accelerator Conf., IPAC2019, Melbourne, Australia

The first electron beams were generated in the 7 MeV section of the short-pulse linear accelerator test facility FLUTE (Ferninfrarot Linac- Und Test-Experiment) at the Karlsruhe Institute of Technology (KIT). In this contribution we show images of the electron beam on a YAG-screen (yttrium aluminum garnet) as well as signals from an integrating current transformer (ICT) and a Faraday cup. Furthermore, the progress of tuning the FLUTE electron bunches for experiments is presented., Proceedings of the 10th Int. Particle Accelerator Conf., IPAC2019, Melbourne, Australia

The storage ring Karlsruhe Research Accelerator (KARA) at KIT operates in a wide energy range from 0.5 to 2.5 GeV. Initially, the ring was designed to serve as a Light Source for synchrotron radiation facility ANKA. Since then different operation modes have been implemented at KARA: in particular, the double bend achromat (DBA) lattice with non-dispersive straight sections, the theoretical minimum emittance (TME) lattice with distributed dispersion, and different versions of low compaction factor optics with highly stretched dispersion function. Short bunches of a few ps pulse width are available at KARA. Low alpha optics have been tested and implemented in a wide operational range of the ring and are now routinely used at 1.3 GeV for studies of CSR-induced beam dynamics and THz bursting in the micro-bunching instability. Different non-linear effects, in particular, residual high order components of magnetic fields generated in insertion devices have been studied and cured. A new operation mode at high vertical tune implemented at KARA essentially improves beam performance during user operation as well as at low alpha regimes., Proceedings of the 10th Int. Particle Accelerator Conf., IPAC2019, Melbourne, Australia

FLUTE (Ferninfrarot Linac- Und Test-Experiment) is a compact versatile linear accelerator at the Karlsruhe Institute of Technology (KIT). It serves as a platform for a variety of accelerator studies as well as a source of strong ultra-short THz pulses for photon science. In the commissioning phase of the 7 MeV low energy section the electron bunches are used to test the different diagnostics systems installed in this section. An example is the split-ring-resonator-experiment. In this contribution we report on the commissioning status of the beam diagnostics and present first beam measurements at FLUTE., Proceedings of the 10th Int. Particle Accelerator Conf., IPAC2019, Melbourne, Australia

The energy spread is an important beam dynamics parameter. It can be derived from measurements of the horizontal bunch size. At the KIT storage ring KARA a fast-gated camera is routinely used for horizontal bunch size measurements with a single-turn resolution for a limited time span. To overcome the limits of the current camera setup in respect to resolution and time span, a high-speed line array with up to 10 Mfps, the KALYPSO system, is foreseen as a successor. The KALYPSO versions range from 256-pixel to 1024-pixel and allow unlimited turn-by-turn imaging of a single bunch at KARA. We successfully tested such a system at our visible light diagnostics port and present first results in this contribution., Proceedings of the 10th Int. Particle Accelerator Conf., IPAC2019, Melbourne, Australia

The compact storage ring for accelerator research and technology (cSTART) is being designed and will be realized at the Institute for Beam Physics and Technology (IBPT) of the Karlsruhe Institute of Technology (KIT). One important goal of the project is to demonstrate injection and storage of a laser wakefield accelerator (LWFA) beam in a storage ring. As a first stage the compact linear accelerator FLUTE will serve as an injector of 50 MeV bunches to test the ring’s performance. A highly non-linear lattice of DBA-FDF type was studied extensively. The specific features of ring optics are reported. A special transfer line from FLUTE to cSTART including bunch compressor and non-linear elements is presented that maintains the ultra-short bunch length of FLUTE., Proceedings of the 10th Int. Particle Accelerator Conf., IPAC2019, Melbourne, Australia

At the storage ring KARA (Karlsruhe Research Accelerator) of the Karlsruhe Institute of Technology (KIT) we have installed a function for the RF phase modulation to the low-level RF system. By choosing proper conditions of the modulation, the electron distribution on the longitudinal phase space can be changed in a large range. There are several applications of this longitudinal manipulation to the accelerator operation: an improvement of the beam lifetime and suppression of collective instabilities. We have performed tracking simulations for the longitudinal beam manipulation by the RF phase modulation. The results have implied that the longitudinal phase space distribution strongly depends on the modulation frequency. We have also performed experiments, which aimed at improving the beam lifetime in 2.5 GeV KARA multi-bunch operations. In this contribution, the low-level RF system at KARA, the simulation and experimental results under the RF phase modulation will be presented. As one of the options of the modulation, we consider manipulation of the internal fine structure in the longitudinal phase space by the modulation., Proceedings of the 10th Int. Particle Accelerator Conf., IPAC2019, Melbourne, Australia

Accelerators with high bunch-repetition rates mandate high-throughput detector electronics to diagnose each individual bunch. KALYPSO with a 256-pixel detector line-array integrated in an fs laser-based electro-optical set-up allows longitudinal bunch profiling with sub-ps resolution as demonstrated at the storage ring ANKA for single-bunch mode operation at 2.7 MHz and also at the Eu-XFEL with a 4.5-MHz micro-bunch train. Improvements will enhance fs-time accuracy, reduce noise, and increase frame-rate. A custom front-end with an application-specific integrated circuit (ASIC) has been developed to operate with 10-MHz frame-rates at low noise. Several linear arrays with up to 1024 pixel and smaller pixel pitch were submitted for production. The development of a low-gain avalanche diode (LGAD) sensor will further improve the time resolution. Detector data is transmitted in the DAQ framework to external GPU-based clusters and processed in real-time at 7 Gbytes/s with a few μs latency. For beam dynamics studies we also develop KAPTURE capable to analyze terahertz detector pulses at GHz-repetition rates. These developments open new windows in beam diagnostics of modern accelerators., Proceedings of the 6th Int. Beam Instrumentation Conf., IBIC2017, Grand Rapids, MI, USA

THz streaking with split ring resonators (SRR) promise ultra-high (sub-femtosecond) temporal resolution even for relativistic electron bunches. A proof-of-principle experiment in collaboration between the University of Bern, the Paul Scherrer Institute (PSI) and the Karlsruhe Institute of Technology (KIT) is currently prepared at the FLUTE facility (Ferninfrarot Linac und Test Experiment) at KIT. Most of the critical components have been designed, tested and set-up in the 7 MeV diagnostics part of FLUTE. In this contribution we will present an update on the experimental set-up and report on SRR configurations which have been optimized for highest THz deflection, while simultaneously accounting for the restrictions of the manufacturing process. Test measurements characterizing the SRR samples and the THz source, which has been matched to the FLUTE gun laser, will also be presented., Proceedings of the 6th Int. Beam Instrumentation Conf., IBIC2017, Grand Rapids, MI, USA

Time-correlated single photon counting (TCSPC) is a versatile tool for various accelerator diagnostics aspects. Amongst others it allows a precise determination of the filling pattern. At the visible light diagnostics port at the Karlsruhe Research Accelerator (KARA), the KIT storage ring, a Single-Photon Avalanche Diode (SPAD) in combination with a histogramming device (PicoHarp) is used. To compensate for possible dead-time effects, a correction scheme was developed and tested successfully. The compensation increases the dynamic range in which accurate measurements are possible and avoids distortion of the measured filling pattern. This contribution presents the experimental setup, as well as a series of benchmark measurements., Proceedings of the 9th Int. Particle Accelerator Conf., IPAC2018, Vancouver, BC, Canada

While recent diffraction-limited storage rings provide bunches with transverse dimensions smaller than the wavelength of the observed synchrotron radiation, the bunch compression in the longitudinal plane is still challenging. The benefit would be single cycle pulses of coherent radiation with many orders of magnitude higher intensity. However, the self-interaction of a short electron bunch with its emitted coherent radiation can lead to micro-bunching instabilities. This effect limits the bunch compression in storage rings currently to the picosecond range. In that range, the bunches emit coherent THz radiation corresponding to their bunch length. In this paper, new measurement setups developed at the Karlsruhe Institute of Technology are described for systematic turn-by-turn investigations of the micro-bunching instability. They lead to a better understanding thereof and enable appropriate observation methods in future efforts of controlling and mastering the instability. Furthermore, the described setups might also be used as high repetition rate bunch compression monitors for bunches of picosecond length and below., Proceedings of the 60th ICFA Advanced Beam Dynamics Workshop on Future Light Sources, FLS2018, Shanghai, China

The storage ring Karlsruhe Research Accelerator (KARA) at KIT operate in a wide energy range from 0.5 to 2.5 GeV. Different non-linear effects, in particular, residual octupole components of the magnetic field of the CATACT wiggler at high field level (2.5 T), proximity of the working point to a vertical sextupole resonance Qy=8/3 and weak coupling octupole resonance 2Qx+2Qy=19, high chromaticity, etc. decrease the beam life time. This is because of the reduced dynamic aperture and momentum acceptance for off-momentum particles. A new operation point at high vertical tune Qy=2.81 was tested. For this, injection and ramping tables have been modified. First the values were optimized by simulations, then during beam tests, to minimize betatron tune shaking during beam-energy ramps. It stabilized high-current beams by the fast-feedback system the whole process: injection at 0.5 GeV, ramping, and operation at 1.3 GeV cycles. It essentially improved life time and beam current. In addition, new low-alpha tables have been created and tested, resulting in the reduction of the momentum compaction factor to 10⁻⁴. Short bunch operation at 0.5GeV injection energy was also tested successfully., Proceedings of the 9th Int. Particle Accelerator Conf., IPAC2018, Vancouver, BC, Canada

High repetition rate diagnostics are required when detecting single-shot electro-optical (EO) bunch profiles. The KIT storage ring KARA (KArlsruhe Research Accelerator) is the first storage ring in the world that has a near-field EO bunch-profile monitor in operation. By imprinting longitudinal electron bunch profiles onto chirped laser pulses, single-shot detection is feasible. However, limitations of available detection systems are challenging: The constraints are either given by the repetition rate or the duration of the consecutive acquisitions. Two strategies can overcome these limitations: Based on the photonic time-stretch method, the ps laser pulses can be stretched to the ns range using km long fibers. The readout with a high-bandwidth oscilloscope then enables a single-shot detection at high repetition rates. The other strategy is the development of dedicated ultra-fast photodetector arrays allowing direct detection of the ps pulses at MHz repetition rates. We developed KALYPSO, a linear detector array with a DAQ allowing to record high data-rates over long time scales. Here, we present recent results of studies of the longitudinal electron bunch dynamics using KALYPSO., Proceedings of the 9th Int. Particle Accelerator Conf., IPAC2018, Vancouver, BC, Canada

The first phase of FLUTE, a new linac based test facility and THz source is currently being commissioned at the Karlsruhe Institute of Technology (KIT). It consist of an RF photo gun and a traveling wave linac accelerating electrons to beam energies of 40 to 50 MeV. The control system is based on a virtualized infrastructure running Ubuntu Linux and Linux KVM. As base for the SCADA system we use EPICS 3.15 with Control System Studio (CSS) for the GUI. The long term data storage is provided by a Cassandra NoSQL database. This contribution will present the architecture and the current status of the FLUTE control system., Proceedings of the 12th Int. Workshop on Emerging Technologies and Scientific Facilities Controls, PCaPAC2018, Hsinchu, Taiwan

FLUTE (Ferninfrarot Linac- Und Test-Experiment) will be a new compact versatile linear accelerator at the KIT. Its primary goal is to serve as a platform for a variety of accelerator studies as well as to generate strong ultra-short THz pulses for photon science. The phase I of the project, which includes the RF photo injector providing electrons at beam energy of 7 MeV and a corresponding diagnostics section, is currently being commissioned. In this contribution, we report on the latest progress of the commissioning phase. The status of the gun conditioning will be given, followed by an overview of the RF system and the laser system., Proceedings of the 9th Int. Particle Accelerator Conf., IPAC2018, Vancouver, BC, Canada

Design of a very large acceptance compact storage ring is underway at the Institute for Beam Physics and Technology of the Karlsruhe Institute of Technology (Germany). Combination of a compact storage ring and a laser wake-field accelerator (LWFA) might be the basis for future compact light sources and advancing user facilities. Meanwhile the post-LWFA beam is not fitted for storage and accumulation in conventional storage rings. New generation rings with adapted features are required. Different geometries and lattices of a ring operating between 50 to 500 MeV energy range were investigated. The model suitable to store the post-LWFA beam with a wide momentum spread (1% to 2%) and ultra-short electron bunches of fs range was chosen as basis for further detailed studies. The DBA-FDF lattice with relaxed settings, split elements and high order optics of tolerable strength allows improving the dynamic aperture up to 20 mm. The momentum acceptance of the compact lattice exceeds 8% while dispersion is limited. The physical program includes turn-by-turn phase compression of a beam, crab cavities, dedicated alpha optics mode of operation, non-linear insertion devices etc., Proceedings of the 9th Int. Particle Accelerator Conf., IPAC2018, Vancouver, BC, Canada