IPAC2022 - List of Authors (Mueller, A.-S.)

Paper	Title	Page
MOPOST041	Dynamic Aperture Studies for the Transfer Line From FLUTE to cSTART	164
SUSPMF062	use link to see paper's listing under its alternate paper code
	J. Schäfer, B. Härer, A.-S. Müller, A.I. Papash, R. Ruprecht, M. Schuh KIT, Karlsruhe, Germany
	Funding: J. Schäfer acknowledges the support by the DFG- funded Doctoral School "Karlsruhe School of Elementary and Astroparticle Physics: Science and Technology". 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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOST041
About •	Received ※ 08 June 2022 — Revised ※ 09 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 24 June 2022
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MOPOPT017	Terahertz Sampling Rates with Photonic Time-Stretch for Electron Beam Diagnostics	263
	O. Manzhura, E. Bründermann, M. Caselle, S.A. Chilingaryan, T. Dritschler, S. Funkner, A. Kopmann, A.-S. Müller, M.J. Nasse, G. Niehues, M.M. Patil, J.L. Steinmann KIT, Karlsruhe, Germany S. Bielawski, E. Roussel, C. Szwaj PhLAM/CERCLA, Villeneuve d’Ascq Cedex, France S. Bielawski, E. Roussel, C. Szwaj PhLAM/CERLA, Villeneuve d’Ascq, France
	Funding: Supported by the Helmholtz Program-Oriented Funding (PoF), research program Matter and Technologies (Detector Technology and System), ANR-DFG ULTRASYNC funding program, CEMPI LABEX and Wavetech CPER. To understand the underlying complex beam diagnostic often large numbers of single-shot measurements must be acquired continuously over a long time with extremely high temporal resolution. Photonic time-stretch is a measurement method that is able to overcome speed limitations of con- ventional digitizers and enable continuous ultra-fast single- shot terahertz spectroscopy with refresh rates of trillions of consecutive frames. In this contribution, a novel ultra- fast data sampling system based on photonic time-stretch is presented and the performance is discussed. THERESA (TeraHErtz REadout SAmpling) is a data acquisition system based on the recent ZYNQ-RFSoC family. THERESA has been developed with an analog bandwidth up to 20 GHz and a sampling rate up to 90 GS/s. When combined with the photonic time-stretch setup, the system will be able to sample a THz signal with an unprecedented frame rate of 8 TS/s. Continuous acquisition for long observation times will open up new possibilities in the detection of rare events in accelerator physics.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOPT017
About •	Received ※ 08 June 2022 — Revised ※ 17 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 05 July 2022
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MOPOPT024	Measuring the Coherent Synchrotron Radiation Far Field with Electro-Optical Techniques	292
	C. Widmann, M. Brosi, E. Bründermann, S. Funkner, A.-S. Müller, M.J. Nasse, G. Niehues, M.-D. Noll, M.M. Patil, M. Reißig, J.L. Steinmann KIT, Karlsruhe, Germany M. Brosi MAX IV Laboratory, Lund University, Lund, Sweden
	Funding: M. M. P. acknowledges the support by the DFG-funded Doctoral School KSETA. C. W. achnowledges funding by BMBF contract number 05K19VKD. For measuring the temporal profile of the coherent synchrotron radiation (CSR) a setup based on electro-optical spectral decoding (EOSD) will be installed as part of the sensor network at the KIT storage ring KARA (Karlsruhe Research Accelerator). The EOSD technique allows a single-shot, phase sensitive measurement of the complete spectrum of the CSR far field radiation at each turn. Therefore, the dynamics of the bunch evolution, e.g. the microbunching, can be observed in detail. Especially, in synchronized combination with the already established near-field EOSD, this method could provide deeper insights in the interplay of bunch profile and CSR generation for each individual electron bunch. For a successful implementation of the EOSD single shot setup, measurements with electro-optical sampling (EOS) are performed. With EOS the THz pulse shape is scanned over several turns by shifting the delay of laser and THz pulse. In this contribution different steps towards the installation of the EOSD far field setup are summarized.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOPT024
About •	Received ※ 07 June 2022 — Revised ※ 13 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 08 July 2022
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MOPOPT025	Development of an Electro-Optical Longitudinal Bunch Profile Monitor at KARA Towards a Beam Diagnostics Tool for FCC-ee	296
	M. Reißig, M. Brosi, E. Bründermann, S. Funkner, B. Härer, A.-S. Müller, G. Niehues, M.M. Patil, R. Ruprecht, C. Widmann KIT, Karlsruhe, Germany
	Funding: The Future Circular Collider Innovation Study (FCCIS) project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant No 951754. M. R. and M. M. P. acknowledge the support by the Doctoral School "Karlsruhe School of Elementary and Astroparticle Physics: Science and Technology". C. W. achnowledges funding by BMBF contract number 05K19VKD. The Karlsruhe Research Accelerator (KARA) at KIT features an electro-optical (EO) near-field diagnostics setup to conduct turn-by-turn longitudinal bunch profile measurements in the storage ring using electro-optical spectral decoding (EOSD). Within the Future Circular Collider Innovation Study (FCCIS) an EO monitor using the same technique is being conceived to measure the longitudinal profile and center-of-charge of the bunches in the future electron-positron collider FCC-ee. This contribution provides an overview of the EO near-field diagnostics at KARA and discusses the development and its challenges towards an effective beam diagnostics concept for the FCC-ee.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOPT025
About •	Received ※ 08 June 2022 — Revised ※ 13 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 05 July 2022
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MOPOPT026	Beam Diagnostics for the Storage Ring of the cSTART Project at KIT	300
	D. El Khechen, E. Bründermann, A. Mochihashi, A.-S. Müller, M.-D. Noll, A.I. Papash, R. Ruprecht, P. Schreiber, M. Schuh, J.L. Steinmann KIT, Eggenstein-Leopoldshafen, Germany
	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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOPT026
About •	Received ※ 08 June 2022 — Revised ※ 10 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 30 June 2022
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MOPOPT027	Transverse and Longitudinal Profile Measurements at the KARA Booster Synchrotron	304
	D. El Khechen, E. Blomley, E. Bründermann, E. Huttel, A. Mochihashi, A.-S. Müller, M.-D. Noll, R. Ruprecht, P. Schreiber, M. Schuh, J.L. Steinmann, C. Widmann KIT, Karlsruhe, Germany
	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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOPT027
About •	Received ※ 08 June 2022 — Revised ※ 10 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 21 June 2022
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TUPOPT068	Transverse and Longitudinal Modulation of Photoinjection Pulses at FLUTE	1174
	M. Nabinger, A.-S. Müller, M.J. Nasse, C. Sax, J. Schäfer, C. Widmann, C. Xu KIT, Karlsruhe, Germany
	Funding: Supported by the Doctoral School "Karlsruhe School of Elementary and Astroparticle Physics: Science and Technology" (KSETA). To generate the electrons to be accelerated, a photoinjection laser is used at the linac-based test facility FLUTE (Ferninfrarot Linac- Und Test Experiment) at the Karlsruhe Institute of Technology (KIT). The properties of the laser pulse, such as intensity, laser spot size or temporal profile, are the first parameters to influence the characteristics of the electron bunches. In order to control the initial parameters of the electrons in the most flexible way possible, the laser optics at FLUTE are therefore supplemented by additional setups that allow transverse and longitudinal laser pulse shaping by using so-called Spatial Light Modulators (SLMs). In the future, the control of the SLMs will be integrated into a Machine Learning (ML) supported feedback system for the optimization of the electron bunch properties. In this contribution the first test experiments and results on laser pulse shaping at FLUTE on the way to this project are presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOPT068
About •	Received ※ 07 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 22 June 2022
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TUPOPT070	Surrogate Modelling of the FLUTE Low-Energy Section	1182
	C. Xu, E. Bründermann, A.-S. Müller, A. Santamaria Garcia, J. Schäfer KIT, Karlsruhe, Germany
	Funding: Supported by the Helmholtz Association (Autonomous Accelerator, ZT-I-PF-5-6) and the DFG-funded Doctoral School "Karlsruhe School of Elementary and Astroparticle Physics: Science and Technology". Numerical beam dynamics simulations are essential tools in the study and design of particle accelerators, but they can be prohibitively slow for online prediction during operation or for systematic evaluations of new parameter settings. Machine learning-based surrogate models of the accelerator provide much faster predictions of the beam properties and can serve as a virtual diagnostic or to augment data for reinforcement learning training. In this paper, we present the first results on training a surrogate model for the low-energy section at the Ferninfrarot Linac- und Test-Experiment (FLUTE).
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOPT070
About •	Received ※ 30 May 2022 — Accepted ※ 15 June 2022 — Issue date ※ 05 July 2022
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WEPOST032	Status Report of the 50 MeV LPA-Based Injector at ATHENA for a Compact Storage Ring	1768
	E. Panofski, C. Braun, J. Dirkwinkel, J.B. Gonzalez, T. Hülsenbusch, A.R. Maier, J. Osterhoff, G. Palmer, P.A. Walker, P. Winkler DESY, Hamburg, Germany E. Bründermann, B. Härer, A.-S. Müller, A.I. Papash, C. Widmann KIT, Karlsruhe, Germany T.F.J. Eichner, L. Hübner, S. Jalas, L. Jeppe, M. Kirchen, P. Messner, M. Schnepp, M. Trunk, C.M. Werle University of Hamburg, Hamburg, Germany M. Kaluza, A. Sävert HIJ, Jena, Germany
	Laser-based plasma accelerators (LPA) have successfully demonstrated their capability to generate high-energy electron beams with intrinsically short bunch lengths and high peak currents at a setup with a small footprint. These properties make them attractive drivers for a broad range of different applications including injectors for rf-driven, ring-based light sources. In close collaboration the Deutsches Elektronen-Synchrotron (DESY), the Karlsruhe Institute of Technology (KIT) and the Helmholtz Institute Jena aim to develop a 50 MeV plasma injector and demonstrate the injection into a compact storage ring. This storage ring will be built within the project cSTART at KIT. As part of the ATHENA (Accelerator Technology HElmholtz iNfrAstructure) project, DESY will design, setup and operate a 50 MeV plasma injector prototype for this endeavor. This contribution gives a status update of the 50 MeV LPA-based injector and presents a first layout of the prototype design at DESY in Hamburg.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOST032
About •	Received ※ 07 June 2022 — Revised ※ 11 June 2022 — Accepted ※ 12 June 2022 — Issue date ※ 14 June 2022
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WEPOST034	Magnetic Characterization of a Superconducting Transverse Gradient Undulator for Compact Laser Wakefield Accelerator-Driven FELs	1772
SUSPMF035	use link to see paper's listing under its alternate paper code
	K. Damminsek, A. Bernhard, H.J. Cha, A.W. Grau, A.-S. Müller, M.S. Ning, Y. Tong KIT, Karlsruhe, Germany S.C. Richter CERN, Meyrin, Switzerland R. Rossmanith DESY, Hamburg, Germany
	Funding: Federal Ministry of Education and Research of Germany and the Development and Promotion of Science and Technology Talents Project (DPST) A transverse gradient undulator (TGU) is a key component compensating for the relatively large energy spread of Laser Wakefield Accelerator (LWFA)-generated electron beams for realizing a compact Free Electron Laser (FEL). A superconducting TGU with 40 periods has been fabricated at the Karlsruhe Institute of Technology (KIT). In this contribution, we report that the superconducting TGU has been commissioned with nominal operational parameters at an off-line test bench. An experimental set-up for mapping the magnetic field on a two-dimensional grid in the TGU gap has been employed for the magnetic characterization. We show the first preliminary results of these measurements showing the longitudinal quality, the transverse gradient and the transient behaviour of the superconducting TGU field.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOST034
About •	Received ※ 08 June 2022 — Revised ※ 14 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 20 June 2022
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WEPOTK057	Towards Direct Detection of the Shape of CSR Pulses with Fast THz Detectors	2190
	J.L. Steinmann, M. Brosi, E. Bründermann, A. Mochihashi, A.-S. Müller, P. Schreiber KIT, Karlsruhe, Germany
	Funding: We acknowledge in part support by the Helmholtz President’s strategic fund IVF "Plasma accelerators". This work is funded in part by the BMBF contract number: 05K19VKD. Coherent synchrotron radiation (CSR) is emitted when the emitting structure is equal to or smaller than the observed wavelength. Consequently, these pulses are very short and most detectors respond with their impulse response, regardless of the pulse length and shape. Here we present single-shot measurements performed at the Karlsruhe Research Accelerator (KARA) using a fast real-time oscilloscope and Schottky barrier detectors sensitive in the sub-THz range. The time response of this setup to CSR pulses emitted by electron bunches during the microbunching instability is shown to be sensitive to the shape of the electron bunch. Our results show how, in the future, the shape of electron bunches can be directly measured using a straightforward setup.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOTK057
About •	Received ※ 08 June 2022 — Revised ※ 14 June 2022 — Accepted ※ 22 June 2022 — Issue date ※ 09 July 2022
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WEPOMS005	Simulations of the Micro-Bunching Instability for SOLEIL and KARA Using Two Different VFP Solver Codes	2237
	M. Brosi, A.-S. Müller, P. Schreiber KIT, Karlsruhe, Germany S. Bielawski, C. Evain, E. Roussel, C. Szwaj PhLAM/CERCLA, Villeneuve d’Ascq Cedex, France
	Funding: M.B. acknowledges the funding by the Helmholtz Association in the frame of the Helmholtz doctoral prize. The project has been supported by the ANR-DFG ULTRASYNC project. PhLAM acknowledges support from the CPER Photonics for Society, and the CEMPI LABEX. The longitudinal dynamics of a bunched electron beam is an important aspect in the study of existing and the development of new electron storage rings. The dynamics depend on different beam parameters as well as on the interaction of the beam with its surroundings. A well established method for calculating the resulting dynamics is to numerically solve the Vlasov-Fokker-Planck equation. Depending on the chosen parameters and the considered wakefields and impedances, different effects can be studied. One common application is the investigation of the longitudinal micro-wave and micro-bunching instabilities. The latter occurs for short electron bunches due to self-interaction with their own emitted coherent synchrotron radiation (CSR). In this contribution, two different VFP solvers are used to simulate the longitudinal dynamics with a focus on the micro-bunching instability at the Soleil synchrotron and the KIT storage ring KARA (Karlsruhe Research Accelerator).
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOMS005
About •	Received ※ 08 June 2022 — Revised ※ 12 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 23 June 2022
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WEPOMS006	Simulation of the Effect of Corrugated Structures on the Longitudinal Beam Dynamics at KARA	2241
	S. Maier, M. Brosi, A. Mochihashi, A.-S. Müller, M.J. Nasse, P. Schreiber, M. Schwarz KIT, Karlsruhe, Germany
	Funding: Supported by the DFG project 431704792 in the ANR-DFG collaboration project ULTRASYNC. S. M. acknowledge the support by the Doctoral School "Karlsruhe School of Elementary and Astroparticle Physics: Science and Technology" (KSETA). Two parallel corrugated plates will be installed at the KIT storage ring KARA (KArlsruhe Research Accelerator). This impedance manipulation structure will be used to study and eventually control the beam dynamics and the emitted coherent synchrotron radiation (CSR). In this contribution, we present the results obtained with the Vlasov-Fokker-Planck solver Inovesa showing the impedance impact of different corrugated structures on the bunch and its emitted CSR power.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOMS006
About •	Received ※ 20 May 2022 — Revised ※ 13 June 2022 — Accepted ※ 23 June 2022 — Issue date ※ 02 July 2022
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WEPOMS022	Detailed Analysis of Transverse Emittance of the FLUTE Electron Bunch	2289
	T. Schmelzer, E. Bründermann, A.-S. Müller, M.J. Nasse, R. Ruprecht, J. Schäfer, M. Schuh, N.J. Smale, P. Wesolowski KIT, Karlsruhe, Germany
	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\&D 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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOMS022
About •	Received ※ 08 June 2022 — Revised ※ 23 June 2022 — Accepted ※ 23 June 2022 — Issue date ※ 28 June 2022
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WEPOMS023	Optimization Studies of Simulated THz Radiation at FLUTE	2292
	C. Xu, E. Bründermann, A.-S. Müller, A. Santamaria Garcia, J. Schäfer, M. Schwarz KIT, Karlsruhe, Germany
	Funding: Supported by the Helmholtz Association (Autonomous Accelerator, ZT-I-PF-5-6) and the DFG-funded Doctoral School "Karlsruhe School of Elementary and Astroparticle Physics: Science and Technology". The linac-based test facility FLUTE (Ferninfrarot Linac Und Test Experiment) at KIT will be used to study novel accelerator technology and provide intense THz pulses. In this paper, we present start-to-end simulation studies of FLUTE with different bunch charges. We employ a parallel Bayesian optimization algorithm for different bunch charges of FLUTE to find optimized accelerator settings for the generation of intense THz radiation.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOMS023
About •	Received ※ 20 May 2022 — Accepted ※ 21 June 2022 — Issue date ※ 10 July 2022
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THPOST007	Slow-Control Loop to Stabilize the RF Power of the FLUTE Electron Gun	2449
	M.-D. Noll, A. Böhm, J. Jelonek, I. Križnar, O. Manzhura, A.-S. Müller, R. Ruprecht, M. Schuh, N.J. Smale KIT, Karlsruhe, Germany
	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 %.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOST007
About •	Received ※ 08 June 2022 — Revised ※ 16 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 24 June 2022
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THPOST008	Status of the FLUTE RF System Upgrade	2452
	A. Malygin, O. Manzhura, A.-S. Müller, R. Ruprecht, M. Schuh, N.J. Smale KIT, Eggenstein-Leopoldshafen, Germany
	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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOST008
About •	Received ※ 08 June 2022 — Revised ※ 13 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 17 June 2022
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THPOST027	Fabrication of Robust Thermal Transition Modules and First Cryogenic Experiment with the Refurbished COLDDIAG	2505
	H.J. Cha, N. Glamann, A.W. Grau, A.-S. Müller, D. Saez de Jauregui KIT, Eggenstein-Leopoldshafen, Germany
	Funding: This work is supported by the BMBF project 05H18VKRB1 HIRING (Federal Ministry of Education and Research). Two sets of thermal transition modules as a key component for the COLDDIAG (cold vacuum chamber for beam heat load diagnostics) refurbishment were manufactured, based on the previous design study. The modules are installed in the existing COLDDIAG cryostat and tested with an operating temperature of approximately 50 K at both a cold bore and a thermal shield. This cool-down experiment is a preliminary investigation aiming at beam heat-load studies at the FCC-hh where the beam screens will be operated at almost the same temperature. In this contribution, we report the fabrication processes of the mechanically robust transition modules and the first thermal measurement results with the refurbished COLDDIAG in a cryogenic environment. The static heat load in the refurbished cryostat remains unchanged, compared to that in the former one (4-K cold bore and 50-K shield with thin transitions), despite the increase in the transition thickness. It originates from the identical temperature at the cold bore and the shield, which can theoretically allow the heat intakes by thermal conduction and radiation between them to vanish.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOST027
About •	Received ※ 16 May 2022 — Accepted ※ 13 June 2022 — Issue date ※ 10 July 2022
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THPOPT006	Beam Dynamics Observations at Negative Momentum Compaction Factors at KARA	2570
	P. Schreiber, M. Brosi, B. Härer, A. Mochihashi, A.-S. Müller, A.I. Papash, R. Ruprecht, M. Schuh KIT, Karlsruhe, Germany
	Funding: We are supported by the DFG-funded "Karlsruhe School of Elementary and Astroparticle Physics: Science and Technology" and European Union’s Horizon 2020 research and innovation programme (No 730871) 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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOPT006
About •	Received ※ 08 June 2022 — Accepted ※ 23 June 2022 — Issue date ※ 08 July 2022
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THPOPT023	Flexible Features of the Compact Storage Ring in the cSTART Project at Karlsruhe Institute of Technology	2620
	A.I. Papash, A. Bernhard, E. Bründermann, D. El Khechen, B. Härer, A.-S. Müller, R. Ruprecht, J. Schäfer, M. Schwarz KIT, Karlsruhe, Germany
	Within the cSTART project (compact storage ring for accelerator research and technology), a Very Large Acceptance compact Storage Ring (VLA-cSR) will be realized at the Institute for Beam Physics and Technology (IBPT) of the Karlsruhe Institute of Technology. (KIT). A modified geometry of a compact storage ring operating at 50 MeV energy range has been studied and main features of the new model are described here. The new design, based on 45° bending magnets, is suitable to store a wide momentum spread beam as well as ultra-short electron bunches in the sub-ps range injected from the plasma cell as well as from the Ferninfrarot Linac- Und Test Experiment (FLUTE). The DBA lattice of the VLA-cSR with different settings and relaxed parameters, split elements and higher order optics of tolerable strength allows to improve the dynamic aperture and momentum acceptance to an acceptable level. This contribution discusses the lattice features in detail, expected lifetime, injection, tolerances and different possible operation schemes of the ring.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOPT023
About •	Received ※ 20 May 2022 — Revised ※ 11 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 02 July 2022
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THPOPT058	Status and Powering Test Results of HTS Undulator Coils at 77 K for Compact FEL Designs	2726
SUSPMF024	use link to see paper's listing under its alternate paper code
	S.C. Richter, A. Bernhard, A.-S. Müller KIT, Karlsruhe, Germany A. Ballarino, T.H. Nes, S.C. Richter, D. Schoerling CERN, Meyrin, Switzerland
	Funding: This work has been supported by the Wolfgang Gentner Program of the German Federal Ministry of Education and Research (grant no. 05E18CHA). The production of low emittance positron beams for future linear and circular lepton colliders, like CLIC or FCC-ee, requires high-field damping wigglers. Just as compact free-electron lasers (FELs) require high-field but as well short-period undulators to emit high energetic, coherent photons. Using high-temperature superconductors (HTS) in the form of coated ReBCO tape superconductors allows higher magnetic field amplitudes at 4 K and larger operating margins as compared to low-temperature superconductors, like Nb-Ti. This contribution discusses the development work on superconducting vertical racetrack (VR) undulator coils, wound from coated ReBCO tape superconductors. The presented VR coils were modularly designed with a period length of 13 mm. Powering tests in liquid nitrogen of multiple vertical racetrack coils were performed at CERN. The results from the measurements are presented for three VR coils and compared with electromagnetic simulations.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOPT058
About •	Received ※ 17 May 2022 — Revised ※ 12 June 2022 — Accepted ※ 14 June 2022 — Issue date ※ 21 June 2022
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THPOPT059	Development of a Transfer Line for LPA-Generated Electron Bunches to a Compact Storage Ring	2730
	B. Härer, E. Bründermann, D. El Khechen, A.-S. Müller, A.I. Papash, S.C. Richter, R. Ruprecht, J. Schäfer, M. Schuh, C. Widmann KIT, Karlsruhe, Germany L. Jeppe Deutsches Elektronen Synchrotron (DESY) and Center for Free Electron Science (CFEL), Hamburg, Germany A.R. Maier, J. Osterhoff, E. Panofski DESY, Hamburg, Germany P. Messner University of Hamburg, Hamburg, Germany
	The injection of LPA-generated beams into a storage ring is considered to be one of the most prominent applications of laser plasma accelerators (LPAs). In a combined endeavour between Karlsruhe Institute of Technology (KIT) and Deutsches Elektronen-Synchrotron (DESY) the key challenges will be addressed with the aim to successfully demonstrate injection of LPA-generated beams into a compact storage ring with large energy acceptance and dynamic aperture. Such a storage ring and the corresponding transfer line are currently being designed within the cSTART project at KIT and will be ideally suited to accept bunches from a 50 MeV LPA prototype developed at DESY. This contribution presents the foreseen layout of the transfer line from the LPA to the injection point of the storage ring and discusses the status of beams optics calculations.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOPT059
About •	Received ※ 05 June 2022 — Revised ※ 15 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 28 June 2022
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Paper

Title

Page

MOPOST041

Dynamic Aperture Studies for the Transfer Line From FLUTE to cSTART

164

SUSPMF062

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J. Schäfer, B. Härer, A.-S. Müller, A.I. Papash, R. Ruprecht, M. Schuh
KIT, Karlsruhe, Germany

Funding: J. Schäfer acknowledges the support by the DFG- funded Doctoral School "Karlsruhe School of Elementary and Astroparticle Physics: Science and Technology".
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.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOST041

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Received ※ 08 June 2022 — Revised ※ 09 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 24 June 2022

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MOPOPT017

Terahertz Sampling Rates with Photonic Time-Stretch for Electron Beam Diagnostics

263

O. Manzhura, E. Bründermann, M. Caselle, S.A. Chilingaryan, T. Dritschler, S. Funkner, A. Kopmann, A.-S. Müller, M.J. Nasse, G. Niehues, M.M. Patil, J.L. Steinmann
KIT, Karlsruhe, Germany
S. Bielawski, E. Roussel, C. Szwaj
PhLAM/CERCLA, Villeneuve d’Ascq Cedex, France
S. Bielawski, E. Roussel, C. Szwaj
PhLAM/CERLA, Villeneuve d’Ascq, France

Funding: Supported by the Helmholtz Program-Oriented Funding (PoF), research program Matter and Technologies (Detector Technology and System), ANR-DFG ULTRASYNC funding program, CEMPI LABEX and Wavetech CPER.
To understand the underlying complex beam diagnostic often large numbers of single-shot measurements must be acquired continuously over a long time with extremely high temporal resolution. Photonic time-stretch is a measurement method that is able to overcome speed limitations of con- ventional digitizers and enable continuous ultra-fast single- shot terahertz spectroscopy with refresh rates of trillions of consecutive frames. In this contribution, a novel ultra- fast data sampling system based on photonic time-stretch is presented and the performance is discussed. THERESA (TeraHErtz REadout SAmpling) is a data acquisition system based on the recent ZYNQ-RFSoC family. THERESA has been developed with an analog bandwidth up to 20 GHz and a sampling rate up to 90 GS/s. When combined with the photonic time-stretch setup, the system will be able to sample a THz signal with an unprecedented frame rate of 8 TS/s. Continuous acquisition for long observation times will open up new possibilities in the detection of rare events in accelerator physics.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOPT017

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Received ※ 08 June 2022 — Revised ※ 17 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 05 July 2022

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MOPOPT024

Measuring the Coherent Synchrotron Radiation Far Field with Electro-Optical Techniques

292

C. Widmann, M. Brosi, E. Bründermann, S. Funkner, A.-S. Müller, M.J. Nasse, G. Niehues, M.-D. Noll, M.M. Patil, M. Reißig, J.L. Steinmann
KIT, Karlsruhe, Germany
M. Brosi
MAX IV Laboratory, Lund University, Lund, Sweden

Funding: M. M. P. acknowledges the support by the DFG-funded Doctoral School KSETA. C. W. achnowledges funding by BMBF contract number 05K19VKD.
For measuring the temporal profile of the coherent synchrotron radiation (CSR) a setup based on electro-optical spectral decoding (EOSD) will be installed as part of the sensor network at the KIT storage ring KARA (Karlsruhe Research Accelerator). The EOSD technique allows a single-shot, phase sensitive measurement of the complete spectrum of the CSR far field radiation at each turn. Therefore, the dynamics of the bunch evolution, e.g. the microbunching, can be observed in detail. Especially, in synchronized combination with the already established near-field EOSD, this method could provide deeper insights in the interplay of bunch profile and CSR generation for each individual electron bunch. For a successful implementation of the EOSD single shot setup, measurements with electro-optical sampling (EOS) are performed. With EOS the THz pulse shape is scanned over several turns by shifting the delay of laser and THz pulse. In this contribution different steps towards the installation of the EOSD far field setup are summarized.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOPT024

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Received ※ 07 June 2022 — Revised ※ 13 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 08 July 2022

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MOPOPT025

Development of an Electro-Optical Longitudinal Bunch Profile Monitor at KARA Towards a Beam Diagnostics Tool for FCC-ee

296

M. Reißig, M. Brosi, E. Bründermann, S. Funkner, B. Härer, A.-S. Müller, G. Niehues, M.M. Patil, R. Ruprecht, C. Widmann
KIT, Karlsruhe, Germany

Funding: The Future Circular Collider Innovation Study (FCCIS) project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant No 951754. M. R. and M. M. P. acknowledge the support by the Doctoral School "Karlsruhe School of Elementary and Astroparticle Physics: Science and Technology". C. W. achnowledges funding by BMBF contract number 05K19VKD.
The Karlsruhe Research Accelerator (KARA) at KIT features an electro-optical (EO) near-field diagnostics setup to conduct turn-by-turn longitudinal bunch profile measurements in the storage ring using electro-optical spectral decoding (EOSD). Within the Future Circular Collider Innovation Study (FCCIS) an EO monitor using the same technique is being conceived to measure the longitudinal profile and center-of-charge of the bunches in the future electron-positron collider FCC-ee. This contribution provides an overview of the EO near-field diagnostics at KARA and discusses the development and its challenges towards an effective beam diagnostics concept for the FCC-ee.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOPT025

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Received ※ 08 June 2022 — Revised ※ 13 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 05 July 2022

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MOPOPT026

Beam Diagnostics for the Storage Ring of the cSTART Project at KIT

300

D. El Khechen, E. Bründermann, A. Mochihashi, A.-S. Müller, M.-D. Noll, A.I. Papash, R. Ruprecht, P. Schreiber, M. Schuh, J.L. Steinmann
KIT, Eggenstein-Leopoldshafen, Germany

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.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOPT026

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Received ※ 08 June 2022 — Revised ※ 10 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 30 June 2022

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MOPOPT027

Transverse and Longitudinal Profile Measurements at the KARA Booster Synchrotron

304

D. El Khechen, E. Blomley, E. Bründermann, E. Huttel, A. Mochihashi, A.-S. Müller, M.-D. Noll, R. Ruprecht, P. Schreiber, M. Schuh, J.L. Steinmann, C. Widmann
KIT, Karlsruhe, Germany

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.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOPT027

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Received ※ 08 June 2022 — Revised ※ 10 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 21 June 2022

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TUPOPT068

Transverse and Longitudinal Modulation of Photoinjection Pulses at FLUTE

1174

M. Nabinger, A.-S. Müller, M.J. Nasse, C. Sax, J. Schäfer, C. Widmann, C. Xu
KIT, Karlsruhe, Germany

Funding: Supported by the Doctoral School "Karlsruhe School of Elementary and Astroparticle Physics: Science and Technology" (KSETA).
To generate the electrons to be accelerated, a photoinjection laser is used at the linac-based test facility FLUTE (Ferninfrarot Linac- Und Test Experiment) at the Karlsruhe Institute of Technology (KIT). The properties of the laser pulse, such as intensity, laser spot size or temporal profile, are the first parameters to influence the characteristics of the electron bunches. In order to control the initial parameters of the electrons in the most flexible way possible, the laser optics at FLUTE are therefore supplemented by additional setups that allow transverse and longitudinal laser pulse shaping by using so-called Spatial Light Modulators (SLMs). In the future, the control of the SLMs will be integrated into a Machine Learning (ML) supported feedback system for the optimization of the electron bunch properties. In this contribution the first test experiments and results on laser pulse shaping at FLUTE on the way to this project are presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOPT068

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Received ※ 07 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 22 June 2022

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TUPOPT070

Surrogate Modelling of the FLUTE Low-Energy Section

1182

C. Xu, E. Bründermann, A.-S. Müller, A. Santamaria Garcia, J. Schäfer
KIT, Karlsruhe, Germany

Funding: Supported by the Helmholtz Association (Autonomous Accelerator, ZT-I-PF-5-6) and the DFG-funded Doctoral School "Karlsruhe School of Elementary and Astroparticle Physics: Science and Technology".
Numerical beam dynamics simulations are essential tools in the study and design of particle accelerators, but they can be prohibitively slow for online prediction during operation or for systematic evaluations of new parameter settings. Machine learning-based surrogate models of the accelerator provide much faster predictions of the beam properties and can serve as a virtual diagnostic or to augment data for reinforcement learning training. In this paper, we present the first results on training a surrogate model for the low-energy section at the Ferninfrarot Linac- und Test-Experiment (FLUTE).

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOPT070

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Received ※ 30 May 2022 — Accepted ※ 15 June 2022 — Issue date ※ 05 July 2022

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WEPOST032

Status Report of the 50 MeV LPA-Based Injector at ATHENA for a Compact Storage Ring

1768

E. Panofski, C. Braun, J. Dirkwinkel, J.B. Gonzalez, T. Hülsenbusch, A.R. Maier, J. Osterhoff, G. Palmer, P.A. Walker, P. Winkler
DESY, Hamburg, Germany
E. Bründermann, B. Härer, A.-S. Müller, A.I. Papash, C. Widmann
KIT, Karlsruhe, Germany
T.F.J. Eichner, L. Hübner, S. Jalas, L. Jeppe, M. Kirchen, P. Messner, M. Schnepp, M. Trunk, C.M. Werle
University of Hamburg, Hamburg, Germany
M. Kaluza, A. Sävert
HIJ, Jena, Germany

Laser-based plasma accelerators (LPA) have successfully demonstrated their capability to generate high-energy electron beams with intrinsically short bunch lengths and high peak currents at a setup with a small footprint. These properties make them attractive drivers for a broad range of different applications including injectors for rf-driven, ring-based light sources. In close collaboration the Deutsches Elektronen-Synchrotron (DESY), the Karlsruhe Institute of Technology (KIT) and the Helmholtz Institute Jena aim to develop a 50 MeV plasma injector and demonstrate the injection into a compact storage ring. This storage ring will be built within the project cSTART at KIT. As part of the ATHENA (Accelerator Technology HElmholtz iNfrAstructure) project, DESY will design, setup and operate a 50 MeV plasma injector prototype for this endeavor. This contribution gives a status update of the 50 MeV LPA-based injector and presents a first layout of the prototype design at DESY in Hamburg.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOST032

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Received ※ 07 June 2022 — Revised ※ 11 June 2022 — Accepted ※ 12 June 2022 — Issue date ※ 14 June 2022

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WEPOST034

Magnetic Characterization of a Superconducting Transverse Gradient Undulator for Compact Laser Wakefield Accelerator-Driven FELs

1772

SUSPMF035

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K. Damminsek, A. Bernhard, H.J. Cha, A.W. Grau, A.-S. Müller, M.S. Ning, Y. Tong
KIT, Karlsruhe, Germany
S.C. Richter
CERN, Meyrin, Switzerland
R. Rossmanith
DESY, Hamburg, Germany

Funding: Federal Ministry of Education and Research of Germany and the Development and Promotion of Science and Technology Talents Project (DPST)
A transverse gradient undulator (TGU) is a key component compensating for the relatively large energy spread of Laser Wakefield Accelerator (LWFA)-generated electron beams for realizing a compact Free Electron Laser (FEL). A superconducting TGU with 40 periods has been fabricated at the Karlsruhe Institute of Technology (KIT). In this contribution, we report that the superconducting TGU has been commissioned with nominal operational parameters at an off-line test bench. An experimental set-up for mapping the magnetic field on a two-dimensional grid in the TGU gap has been employed for the magnetic characterization. We show the first preliminary results of these measurements showing the longitudinal quality, the transverse gradient and the transient behaviour of the superconducting TGU field.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOST034

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Received ※ 08 June 2022 — Revised ※ 14 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 20 June 2022

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WEPOTK057

Towards Direct Detection of the Shape of CSR Pulses with Fast THz Detectors

2190

J.L. Steinmann, M. Brosi, E. Bründermann, A. Mochihashi, A.-S. Müller, P. Schreiber
KIT, Karlsruhe, Germany

Funding: We acknowledge in part support by the Helmholtz President’s strategic fund IVF "Plasma accelerators". This work is funded in part by the BMBF contract number: 05K19VKD.
Coherent synchrotron radiation (CSR) is emitted when the emitting structure is equal to or smaller than the observed wavelength. Consequently, these pulses are very short and most detectors respond with their impulse response, regardless of the pulse length and shape. Here we present single-shot measurements performed at the Karlsruhe Research Accelerator (KARA) using a fast real-time oscilloscope and Schottky barrier detectors sensitive in the sub-THz range. The time response of this setup to CSR pulses emitted by electron bunches during the microbunching instability is shown to be sensitive to the shape of the electron bunch. Our results show how, in the future, the shape of electron bunches can be directly measured using a straightforward setup.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOTK057

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Received ※ 08 June 2022 — Revised ※ 14 June 2022 — Accepted ※ 22 June 2022 — Issue date ※ 09 July 2022

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WEPOMS005

Simulations of the Micro-Bunching Instability for SOLEIL and KARA Using Two Different VFP Solver Codes

2237

M. Brosi, A.-S. Müller, P. Schreiber
KIT, Karlsruhe, Germany
S. Bielawski, C. Evain, E. Roussel, C. Szwaj
PhLAM/CERCLA, Villeneuve d’Ascq Cedex, France

Funding: M.B. acknowledges the funding by the Helmholtz Association in the frame of the Helmholtz doctoral prize. The project has been supported by the ANR-DFG ULTRASYNC project. PhLAM acknowledges support from the CPER Photonics for Society, and the CEMPI LABEX.
The longitudinal dynamics of a bunched electron beam is an important aspect in the study of existing and the development of new electron storage rings. The dynamics depend on different beam parameters as well as on the interaction of the beam with its surroundings. A well established method for calculating the resulting dynamics is to numerically solve the Vlasov-Fokker-Planck equation. Depending on the chosen parameters and the considered wakefields and impedances, different effects can be studied. One common application is the investigation of the longitudinal micro-wave and micro-bunching instabilities. The latter occurs for short electron bunches due to self-interaction with their own emitted coherent synchrotron radiation (CSR). In this contribution, two different VFP solvers are used to simulate the longitudinal dynamics with a focus on the micro-bunching instability at the Soleil synchrotron and the KIT storage ring KARA (Karlsruhe Research Accelerator).

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOMS005

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Received ※ 08 June 2022 — Revised ※ 12 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 23 June 2022

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WEPOMS006

Simulation of the Effect of Corrugated Structures on the Longitudinal Beam Dynamics at KARA

2241

S. Maier, M. Brosi, A. Mochihashi, A.-S. Müller, M.J. Nasse, P. Schreiber, M. Schwarz
KIT, Karlsruhe, Germany

Funding: Supported by the DFG project 431704792 in the ANR-DFG collaboration project ULTRASYNC. S. M. acknowledge the support by the Doctoral School "Karlsruhe School of Elementary and Astroparticle Physics: Science and Technology" (KSETA).
Two parallel corrugated plates will be installed at the KIT storage ring KARA (KArlsruhe Research Accelerator). This impedance manipulation structure will be used to study and eventually control the beam dynamics and the emitted coherent synchrotron radiation (CSR). In this contribution, we present the results obtained with the Vlasov-Fokker-Planck solver Inovesa showing the impedance impact of different corrugated structures on the bunch and its emitted CSR power.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOMS006

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Received ※ 20 May 2022 — Revised ※ 13 June 2022 — Accepted ※ 23 June 2022 — Issue date ※ 02 July 2022

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WEPOMS022

Detailed Analysis of Transverse Emittance of the FLUTE Electron Bunch

2289

T. Schmelzer, E. Bründermann, A.-S. Müller, M.J. Nasse, R. Ruprecht, J. Schäfer, M. Schuh, N.J. Smale, P. Wesolowski
KIT, Karlsruhe, Germany

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\&D 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.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOMS022

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Received ※ 08 June 2022 — Revised ※ 23 June 2022 — Accepted ※ 23 June 2022 — Issue date ※ 28 June 2022

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WEPOMS023

Optimization Studies of Simulated THz Radiation at FLUTE

2292

C. Xu, E. Bründermann, A.-S. Müller, A. Santamaria Garcia, J. Schäfer, M. Schwarz
KIT, Karlsruhe, Germany

Funding: Supported by the Helmholtz Association (Autonomous Accelerator, ZT-I-PF-5-6) and the DFG-funded Doctoral School "Karlsruhe School of Elementary and Astroparticle Physics: Science and Technology".
The linac-based test facility FLUTE (Ferninfrarot Linac Und Test Experiment) at KIT will be used to study novel accelerator technology and provide intense THz pulses. In this paper, we present start-to-end simulation studies of FLUTE with different bunch charges. We employ a parallel Bayesian optimization algorithm for different bunch charges of FLUTE to find optimized accelerator settings for the generation of intense THz radiation.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOMS023

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Received ※ 20 May 2022 — Accepted ※ 21 June 2022 — Issue date ※ 10 July 2022

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THPOST007

Slow-Control Loop to Stabilize the RF Power of the FLUTE Electron Gun

2449

M.-D. Noll, A. Böhm, J. Jelonek, I. Križnar, O. Manzhura, A.-S. Müller, R. Ruprecht, M. Schuh, N.J. Smale
KIT, Karlsruhe, Germany

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 %.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOST007

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Received ※ 08 June 2022 — Revised ※ 16 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 24 June 2022

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THPOST008

Status of the FLUTE RF System Upgrade

2452

A. Malygin, O. Manzhura, A.-S. Müller, R. Ruprecht, M. Schuh, N.J. Smale
KIT, Eggenstein-Leopoldshafen, Germany

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.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOST008

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Received ※ 08 June 2022 — Revised ※ 13 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 17 June 2022

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THPOST027

Fabrication of Robust Thermal Transition Modules and First Cryogenic Experiment with the Refurbished COLDDIAG

2505

H.J. Cha, N. Glamann, A.W. Grau, A.-S. Müller, D. Saez de Jauregui
KIT, Eggenstein-Leopoldshafen, Germany

Funding: This work is supported by the BMBF project 05H18VKRB1 HIRING (Federal Ministry of Education and Research).
Two sets of thermal transition modules as a key component for the COLDDIAG (cold vacuum chamber for beam heat load diagnostics) refurbishment were manufactured, based on the previous design study. The modules are installed in the existing COLDDIAG cryostat and tested with an operating temperature of approximately 50 K at both a cold bore and a thermal shield. This cool-down experiment is a preliminary investigation aiming at beam heat-load studies at the FCC-hh where the beam screens will be operated at almost the same temperature. In this contribution, we report the fabrication processes of the mechanically robust transition modules and the first thermal measurement results with the refurbished COLDDIAG in a cryogenic environment. The static heat load in the refurbished cryostat remains unchanged, compared to that in the former one (4-K cold bore and 50-K shield with thin transitions), despite the increase in the transition thickness. It originates from the identical temperature at the cold bore and the shield, which can theoretically allow the heat intakes by thermal conduction and radiation between them to vanish.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOST027

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Received ※ 16 May 2022 — Accepted ※ 13 June 2022 — Issue date ※ 10 July 2022

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THPOPT006

Beam Dynamics Observations at Negative Momentum Compaction Factors at KARA

2570

P. Schreiber, M. Brosi, B. Härer, A. Mochihashi, A.-S. Müller, A.I. Papash, R. Ruprecht, M. Schuh
KIT, Karlsruhe, Germany

Funding: We are supported by the DFG-funded "Karlsruhe School of Elementary and Astroparticle Physics: Science and Technology" and European Union’s Horizon 2020 research and innovation programme (No 730871)
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.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOPT006

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Received ※ 08 June 2022 — Accepted ※ 23 June 2022 — Issue date ※ 08 July 2022

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THPOPT023

Flexible Features of the Compact Storage Ring in the cSTART Project at Karlsruhe Institute of Technology

2620

A.I. Papash, A. Bernhard, E. Bründermann, D. El Khechen, B. Härer, A.-S. Müller, R. Ruprecht, J. Schäfer, M. Schwarz
KIT, Karlsruhe, Germany

Within the cSTART project (compact storage ring for accelerator research and technology), a Very Large Acceptance compact Storage Ring (VLA-cSR) will be realized at the Institute for Beam Physics and Technology (IBPT) of the Karlsruhe Institute of Technology. (KIT). A modified geometry of a compact storage ring operating at 50 MeV energy range has been studied and main features of the new model are described here. The new design, based on 45° bending magnets, is suitable to store a wide momentum spread beam as well as ultra-short electron bunches in the sub-ps range injected from the plasma cell as well as from the Ferninfrarot Linac- Und Test Experiment (FLUTE). The DBA lattice of the VLA-cSR with different settings and relaxed parameters, split elements and higher order optics of tolerable strength allows to improve the dynamic aperture and momentum acceptance to an acceptable level. This contribution discusses the lattice features in detail, expected lifetime, injection, tolerances and different possible operation schemes of the ring.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOPT023

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Received ※ 20 May 2022 — Revised ※ 11 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 02 July 2022

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THPOPT058

Status and Powering Test Results of HTS Undulator Coils at 77 K for Compact FEL Designs

2726

SUSPMF024

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S.C. Richter, A. Bernhard, A.-S. Müller
KIT, Karlsruhe, Germany
A. Ballarino, T.H. Nes, S.C. Richter, D. Schoerling
CERN, Meyrin, Switzerland

Funding: This work has been supported by the Wolfgang Gentner Program of the German Federal Ministry of Education and Research (grant no. 05E18CHA).
The production of low emittance positron beams for future linear and circular lepton colliders, like CLIC or FCC-ee, requires high-field damping wigglers. Just as compact free-electron lasers (FELs) require high-field but as well short-period undulators to emit high energetic, coherent photons. Using high-temperature superconductors (HTS) in the form of coated ReBCO tape superconductors allows higher magnetic field amplitudes at 4 K and larger operating margins as compared to low-temperature superconductors, like Nb-Ti. This contribution discusses the development work on superconducting vertical racetrack (VR) undulator coils, wound from coated ReBCO tape superconductors. The presented VR coils were modularly designed with a period length of 13 mm. Powering tests in liquid nitrogen of multiple vertical racetrack coils were performed at CERN. The results from the measurements are presented for three VR coils and compared with electromagnetic simulations.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOPT058

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Received ※ 17 May 2022 — Revised ※ 12 June 2022 — Accepted ※ 14 June 2022 — Issue date ※ 21 June 2022

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THPOPT059

Development of a Transfer Line for LPA-Generated Electron Bunches to a Compact Storage Ring

2730

B. Härer, E. Bründermann, D. El Khechen, A.-S. Müller, A.I. Papash, S.C. Richter, R. Ruprecht, J. Schäfer, M. Schuh, C. Widmann
KIT, Karlsruhe, Germany
L. Jeppe
Deutsches Elektronen Synchrotron (DESY) and Center for Free Electron Science (CFEL), Hamburg, Germany
A.R. Maier, J. Osterhoff, E. Panofski
DESY, Hamburg, Germany
P. Messner
University of Hamburg, Hamburg, Germany

The injection of LPA-generated beams into a storage ring is considered to be one of the most prominent applications of laser plasma accelerators (LPAs). In a combined endeavour between Karlsruhe Institute of Technology (KIT) and Deutsches Elektronen-Synchrotron (DESY) the key challenges will be addressed with the aim to successfully demonstrate injection of LPA-generated beams into a compact storage ring with large energy acceptance and dynamic aperture. Such a storage ring and the corresponding transfer line are currently being designed within the cSTART project at KIT and will be ideally suited to accept bunches from a 50 MeV LPA prototype developed at DESY. This contribution presents the foreseen layout of the transfer line from the LPA to the injection point of the storage ring and discusses the status of beams optics calculations.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOPT059

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Received ※ 05 June 2022 — Revised ※ 15 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 28 June 2022

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