Virtual MT ARD ST3 Meeting 2020 in Karlsruhe

23 Sept 2020, 13:50 → 24 Sept 2020, 18:00 Europe/Berlin

Virtual Meeting via Zoom

Anke-Susanne Mueller (KIT), Erik Bruendermann (KIT), Holger Schlarb (DESY)

The 2020 edition of the MT ARD ST3 meeting will take place in a purely online format. The Helmholtz Initiative for Accelerator Research & Development (ARD) was established to strengthen development in accelerator physics and technology and to ensure international competitiveness. In this framework, accelerator scientists push the limits of today’s technology in a research network of six Helmholtz centers (Deutsches Elektronen-Synchrotron (DESY) in Hamburg and Zeuthen, Helmholtz Zentrum Dresden-Rossendorf (HZDR), Forschungszentrum Jülich (FZJ), Helmholtz Zentrum for Heavy Ion Research GSI in Darmstadt, Karlsruhe Insitute for Technology (KIT), and Helmholtz Zentrum Berlin for Materials and Energy (HZB) ), two Helmholtz institutes, eleven universities, two Max-Planck institutes, and the Max-Born institute. As the ARD ST3 will broaden its scope from current “ps – fs Electron and Photon Beams” to “Advanced beam controls, beam diagnostics and beam dynamics” in POF4, the eighth ARD topical workshop for ST3 will be held virtual from Sep. 23 to 24. In addition to the review of the progress in the three fundamental areas of current research of short pulse particle accelerators, this workshop also aims for bringing the scientists from universities and Helmholtz centers together that are involved in the current subtopic 3 (ST3) “ps – fs Electron and Photon Beams” of the ARD program with the scientists who have been and will be in the ST3 POF4 topics. It shall also serve to further strengthen collaborative projects at and between the different accelerator facilities. The workshop shall also serve to educate young researchers and students participating in projects and experiments within ST3.

Wednesday, 23 September

13:50 Arrival & Organization

Erik Bründermann

Welcome

Convener: Anke-Susanne Mueller (KIT)

1 Welcome

Speaker: Anke-Susanne Mueller (KIT)

14:10 Q & A

Status and future plans

Convener: Dr Erik Bruendermann (KIT)

2 Status and future plans of DESY

Speaker: Dr Holger Schlarb (DESY)

Slides ARD-ST3-DESY-Acc_20200923_final.pdf

14:35 Q & A

3 Status and future plans of HZDR

Speaker: Dr Pavel Evtushenko (HZDR / ELBE)

Slides 2020_ARD-ST3-HZDR_P.Evtushenko.pdf

15:00 Q & A

4 Status of KIT test facilities and outlook

Speaker: Dr Marcel Schuh (KIT - ANKA)

Slides 2020-09-23_MT_ARD_ST3_KIT_Status_Schuh.pdf

15:25 Q & A

Group picture

15:40 Coffee Break

Status and future plans

Convener: Prof. Andreas Jankowiak (HZB)

5 Status and future plans of HZB

Speaker: Prof. Andreas Jankowiak (HZB)

Slides 2020-09-23-ARD-ST3-Meeting-HZB_Status_and_Plans-AJ.pdf

16:20 Q & A

6 Status and future plans of PITZ

Speaker: Mikhail Krasilnikov (DESY Zeuthen)

Slides PITZstatus4ARDST3_2020_v6a.pdf

16:40 Q & A

7 Status and future plans of FAIR

Speaker: Jörg Blaurock (GSI)

Slides 20200923_ARD-ST3_Blaurock.pdf

17:05 Q & A

17:10 End 1. Day

Erik Bründermann

Thursday, 24 September

08:50 Arrival & Organization

Erik Bründermann

Beam Dynamics: Talks

Convener: Dr Paul Goslawski (Helmholtz-Zentrum Berlin, HZB)

8 ARES Commissioning first measurement and future development

Speaker: Dr Florian Burkart (DESY)

Slides ARD_ST3_ARES_FB_out.pdf

09:15 Q & A

9 Fast MHz helicity flipping at BESSY

Speaker: Dr Paul Goslawski (Helmholtz-Zentrum Berlin, HZB)

Slides 20200923_ARDST3_MHzFlippingTRIBs_PG.pdf

09:35 Q & A

10 Studying the nonlinear properties of an accelerator / storage ring via tune scans

Speaker: Giuliano Franchetti (GSI)

Slides 3_ard-st3-Franchetti.pdf

09:55 Q & A

10:00 Coffee Break

Beam Dynamics: Speed Talks

Convener: Dr Andrea Santamaria (KIT)

11 Emittance Reduction of RF Photoinjector Generated Electron Beams by Transverse Laser Beam Shaping

Linac based X-ray free electron laser demand a high beam quality from the electron source, therefore RF photoinjectors are used to generate the electron bunches for state of the art beam brightness. One important figure of merit for these injectors is the transverse emittance of the generated electron beam, which can be minimized by shaping the photocathode laser pulses. Best performance can be achieved with ellipsoidal laser pulses, but 3D shaping is technically challenging. Typically, a quasi-uniform transverse laser profile is truncated from the Gaussian profile generated by the laser with an aperture to reduce the transverse nonlinear space charge forces. This is investigated in detail by optimizing the laser transverse profile at the Photoinjector Test facility at DESY in Zeuthen (PITZ), where photoinjector R&D is conducted for the E-XFEL and FLASH free electron lasers at DESY in Hamburg. In this contribution we present experimental results at high acceleration gradients (up to 60 MV/m) for both 250 pC and 500 pC. For a bunch charge of 500 pC an emittance reduction of about 30% compared to the commonly used transverse flat-top laser distribution was achieved.

Speaker: Dr Matthias Gross (DESY)

Slides Emittance_Reduction_of_RF_Photoinjector_Generated_Electron_Beams_MGross.pdf

12 Beam Dynamics Simulations for PITZ Bunch Compressor

A magnetic bunch compressor is a part of an accelerator-based THz source prototype for pump-probe experiments at the European XFEL at the Photo Injector Test Facility at DESY in Zeuthen (PITZ). We study the performance of the bunch compressor by beam dynamics simulations. However, a coherent radiation effect challenges our study case involving high space charge up to 2 nC, low energy beam of ~17 MeV, and a large bending angle of 19 degrees. A start-to-end simulation optimizer has been developed by combining the use of program ASTRA, IMPACT-T, and OCELOT to support our test experiments on the THz source prototype. Preliminary simulation results will be presented.

Speaker: Anusorn Lueangaramwong (Deutsches Elektronen-Synchrotron DESY, Platanenallee 6, 15738 Zeuthen, Germany)

Slides BCspeedtalk4ARDST3_2020_v2_AL20200921.pdf

13 Efforts in the Negative Momentum Compaction Regime at KARA

New operation modes are often considered during the development of new synchrotron light sources. An understanding of the instabilities involved is inevitable for a successful operation of these schemes. At the test facility KARA (Karlsruhe Research Accelerator), new modes can be implemented and tested employing a variety of performant beam diagnostics devices which allow the investigation of instabilities in those regimes. Recently, multiple negative momentum compaction optics have been established at KARA with the possibility to choose from a variety of momentum compaction factors. This contribution presents a quick overview of the status and shows first measurements in this regime.

Speaker: Mr Patrick Schreiber (KIT)

Slides MT_ARD_ST3_Speedtalk_PSchreiber.pdf

14 LCLS-I undulator horizontal gradient modeling for THz@PITZ

The Photo Injector Test Facility at DESY in Zeuthen (PITZ) develops a prototype of an accelerator based THz source for pump-probe experiments at the European XFEL. For the proof-of-principle experiments an LCLS-I undulator will be installed in a second PITZ tunnel downstream of the accelerator. Two LCLS-I undulators (on loan from SLAC) have arrived at Hamburg in August 2019. The fields of the undulator L143-112000-26 have been re-measured at DESY Hamburg and are consistent with SLAC measurement. A model for 3D field reconstruction based on the undulator magnetic measurements has been developed. This includes also a horizontal gradient of the vertical undulator field. Beam tracking has revealed that the transverse gradient will lead to an off-axis trajectory in the horizontal plane. This offset has to be corrected by steering coils which design is presented as well.

Speaker: Mikhail Krasilnikov (DESY Zeuthen)

Slides THzatPITZ_LCLSIundulatorSpeedTalk4ARDST3_2020_v2.pdf

15 First-order detection for the Steady-State Microbunching experiment at the MLS

Rising demand for high-power radiation sources has inspired the proposal of the Steady-State Microbunching mechanism. Its implementation will allow the generation of coherent radiation at a storage ring facility, creating a high peak power/high average power radiation source over a wide range of wavelengths up to the EUV range. A Proof-of-Principle experiment is conducted at the Metrology Light Source (MLS) in Berlin and has already conclusively shown that a microbunch structure can be sustained over a full turn on a storage ring. The coherent signal detection has so far been conducted at higher undulator harmonics. This will be complemented by a fundamental mode detection setup as part of my Master’s thesis, allowing the completion of the first phase of the PoP experiment.

Speaker: Mr Arnold Kruschinski (Helmholtz-Zentrum Berlin)

Slides PresentationSpeedTalkSSMB.pdf

10:45 Coffee Break

Beam Diagnostics: Talks

Convener: Dr Gudrun Niehues (KIT)

16 Phase space tomography at MHz-repetition rates at KARA

Speaker: Stefan Funkner (KIT)

Slides 1_Tomography_of_Electron_Bunches__Funkner.pdf

11:20 Q & A

17 Latest developments and results in time resolving IR-THz photon pulse metrology

Speaker: Dr Sergey Kovalev (Helmholtz Zentrum Dresden Rossendorf)

Slides ARD_short.pdf

11:40 Q & A

18 PolariX measurements and first results

Speaker: Dr Richard D'Arcy (DESY)

Slides 2020-09-24_PolariX.pdf

12:00 Q & A

12:05 Organization

Erik Bründermann

12:10 Lunch

13:10 Arrival

Beam Diagnostics: Speed Talks

Convener: Miriam Brosi (KIT)

19 Trip Event Logger - Fault Analysis and HPC

The Trip Event Logger is a fault diagnosis tool to detect errors, inform the operators and trigger automatic supervisory actions. Further goals are to provide information for a fault tree and event tree analysis as well as a database of labeled faulty data sets for offline analysis. The tool is based on the C++ framework ChimeraTK Application Core. With this close interconnection to the control system it is possible not only to monitor but also to intervene as it is of great importance for supervisory tasks. The core of the tool are the fault analysis modules ranging from simple ones (e.g., limit checking) to advanced ones (model-based, machine learning, etc.).

Speaker: Dr Jan Timm (DESY)

Slides MTARDST3-2020-SpeeTalk-Timm.pdf

20 Discussion of suitable diagnostic components for the cSTART project

The compact STorage ring for Accelerator Research and Technology (cSTART) is a project which aims to demonstrate the injection and storage of a laser wakefield accelerated (LWFA) beam. The project mainly consists of an injector, a transfer line and a storage ring. The plan is to have two injectors, one is the photo-injector FLUTE (Ferninfrarot Linac- und Test-Experiment) and the other one is a LWFA injection line. Different kinds of challenges characterize this project, starting from the lattice design and ending with the commissioning. Beam diagnostics is one of these challenges and plays a key role in the success of the commissioning and the storage of the beam. Ultra-short bunches (in the order of 5 fs) with typically low bunch charge (down to 1 pC) are to be stored in the VLA-cSR (Very Large Acceptance compact Storage Ring) at high repetition rates. Therefore, to be able to measure a signal of such bunches, we need very sensitive and high dynamic range diagnostics with very fast readout electronics. In this presentation, an overview of the cSTART project will be presented, along with a report on the recent studies and suggestions on a suitable beam diagnostic system for the storage ring.

Speaker: Dr Dima El Khechen (KIT, Karlsruhe Institute of Technology)

Slides 2_speed_talk_ElKhechen_v2.pdf

21 Cathode response time measurements in a high gradient photo injector

Photoinjectors are the primary choice for high-brightness electron beam sources today. A key element of these is the photocathode. In applications that require high average currents, semiconductor photocathodes are usually used due to their high quantum efficiency. Contrary to metal cathodes, electrons are not just extracted from the surface of a semiconductor but photons of the photocathode laser can penetrate up to several nanometers into the cathode material. On their way to the surface, these electrons can be scattered of phonons and thereby vary the path length they travel until they are emitted. These effects lead to a net delay and a lengthening of the extracted bunch w.r.t. the photocathode laser pulse. We present here first measurements of the cathode time response for Cs2Te cathodes, confirming previous theoretical models and enabling further studies of photocathode properties.

Speaker: Gregor Loisch (DESY Zeuthen)

Slides 20200924_ST3_Speedtalk_RespT_GL.pdf

22 Status of the STRIDENAS Beam Profile Monitor for Low-Charge Electron Beams

A novel type of beam profile monitor called STRIDENAS, dedicated to the detection of low-charge electron beams, is currently being developed at DESY. It aims at bridging the gap between conventional multi-pC scintillating screens and single particle detectors from high energy physics. This is needed, for example, for studies on novel acceleration techniques at the ARES electron linac, such as dielectric laser acceleration (DLA), which typically feature a sub-pC charge. STRIDENAS is based on silicon strip sensors from the ATLAS inner tracker upgrade and is being developed to measure low-charge distributions with a spatial resolution of around 100 micrometers. Sensor characterization and first proof-of-principle tests with a detector prototype using single electrons from the DESY II Test Beam Facility have successfully been performed. Here, the latest advances and future steps towards first proof-of-principle experiments using electron bunches from ARES are presented.

Speaker: Sonja Jaster-Merz (DESY)

Slides STRIDENAS_ST3_workshop_jaster-merz_slides.pdf

23 The split ring resonator experiment at FLUTE

A status report of the split ring resonator experiment at FLUTE is given.

Speaker: Dr Michael Nasse (Karlsruhe Institute of Technology)

Slides 2020-09-23_24_Helmholtz_ARD-ST3_KIT_Nasse_FLUTE_SRR2.pdf

24 Latency comparison of ADCs with different interfaces

The latency of the controller is an important parameter to consider in digital feedback systems, for example in LLRF controller for normal conducting RF structures. Contributing to the total latency of the controller are also the ADC internal pipeline and the interface between the ADC and the FPGA. In this talk different ADCs with different interfaces are compared: a 125 MSPS ADC with an LVDS interface, a 500/800 MSPS ADC also with an LVDS interface, a 1 GSPS ADC with a JESD204B interface and an RFSoC. The measurement method evaluates the latency from the ADC input to the point where the data is available in the FPGA. With the current and future developments on the MicroTCA platform users are presented with numerous options for digitizers. The results presented here put into perspective an important parameter of these devices.

Speaker: Mr Jan Marjanovic (DESY)

Slides ard_st3_adc_latency.pdf

25 A Step Towards fs-Resolution Arrival-Time Measurements for Ultra-Low Charged Bunches in X-ray Free Electron Lasers

For future experiments at the European XFEL an ultra-low charge mode is foreseen. The tight requirements on the facility wide synchronization system are even more crucial in these experiments, while the conditions for the electro-optical bunch arrival time monitors become worse. In this talk the first step towards a sufficient improvement of the arrival-time measurement is presented. Following from the radial dependency of the sensed electric field, an aperture reduction from 40.5 mm to 10 mm gives a significant increase. In simulations a factor of 3.9 is found with a well-shaped bipolar signal and acceptable ringing. This first step contributes nearly 60 % of the overall goal and will be accompanied by further improvements.

Speaker: Mr Bernhard Scheible (Technische Hochschule Mittelhessen)

Slides 7_Speedtalk_ARD-ST3-2020_Scheible.pdf

13:50 Coffee Break

Beam Controls: Talks

Convener: Dr Holger Schlarb (DESY)

26 Precision synchronization results from EuXFEL/FLASH

Speaker: Dr Sebastian Schulz (Deutsches Elektronen-Synchrotron)

Slides Latest_Results_of_Precision_Synchronization_at_EuXFEL_and_FLASH.pptx

14:20 Q & A

27 Digital LLRF at ELBE: Performance and first impressions of user operation

A digital LLRF control has been implemented at the CW linac ELBE at Helmholtz-Zentrum Dresden-Rossendorf. The system is based on the MicroTCA.4 standard and drives four superconducting TESLA cavities and two normal conducting buncher cavities. The system enables a higher flexibility of the field control, improved diagnostics and field stability compared to the analogue system which was used before. The presentation will give an overview on the system performance in terms of noise measurements. In addition a review of the user operation started in August 2020 will be given. Finally, planned future features are presented.

Speaker: Klaus Zenker (Helmholtz-Zentrum Dresden-Rossendorf)

Slides ARD_ST3_zenker_edit.pdf

14:40 Q & A

28 Artificial intelligence activities at KIT for accelerators

Speaker: Andrea Santamaria Garcia (KIT)

Slides 2_2020-09-24_MT_ARD_ST3_SANTAMARIA.pdf

15:00 Q & A

29 Realization of fast closed orbit feedback system for SIS18 synchrotron

A fast and robust closed orbit feedback (COFB) system is realized at SIS18 synchrotron of GSI for the orbit correction during the acceleration cycles. ORM variation over the fast ramps due to the triplet-to-doublet quadrupole transition from injection to extraction posed a unique challenge for the stability of the feedback system. The theoretical investigations are presented made using control theory for the performance and stability of the COFB system in the presence of the ORM model mismatch between the controller and the system. System identification for the frequency response of the steerer magnets as well as a full-loop measurement is also presented. COFB hardware is described along with the successful demonstration of the orbit correction during the ramp at SIS18 for variable machine settings.

Speaker: Mr Sajjad Hussain Mirza (GSI Darmstadt)

Slides 4_Sajjad_Mirza_MT_ARD_ST3_meeting-pdf.pdf

15:20 Q & A

15:25 Coffee Break

Beam Controls: Speed Talks

Convener: Annika Eichler (DESY)

30 Sub-10 fs Synchronization of the SINBAD Injector Laser

The Accelerator Research Experiment at SINBAD (ARES) is a conventional S-band linear accelerator which will be capable of producing ultra-short electron bunches with duration of a few femtoseconds and energy of up to 100 MeV. The SINBAD injector laser synchronization has recently been extended with with an advanced laser-to-RF phase detector, which is based on an integrated Mach-Zenhnder amplitude modulator and allows direct interaction between the injector laser pulse train and the RF reference signal. We are now able to provide sub-10 fs synchronization stability for the SINBAD injector laser and to explore the full potential of the facility.

Speaker: Mr Thorsten Lamb (DESY)

Slides ARD_ST_SINBAD_IL_Sync_TL.pdf

31 Attosecond RF Receivers Based on Carrier Suppression : Status Report

The carrier suppression method offers a leap in terms of measured amplitude and phase resolution compared to other methods. The method allows overcoming the ADC noise barrier which can give resolution improvements of 30 dB compared to other methods. Our current work includes mostly finding the best technologies of various building blocks which should ultimately lead to a viable testing of a prototype on an accelerator. The goal of this contribution is to give a short status summary of what has been achieved so far. Furthermore an overview of the tested building blocks (phase shifters and attenuators) is given. In Parallel we have been also exploring possible ways of non-invasive phase calibration methods. We present the basic concepts and the so far obtained results of the later.

Speaker: Uros Mavric (DESY)

Slides LS_Speedtalk.pdf

32 Toward an Optimal Beam-Based Feedback Control for a Continuous-Wave Linear Accelerator

The design of a beam-based feedback control for the superconducting electron linear accelerator ELBE is progressing through its modelling stage. By taking into account the continuous-wave mode of this accelerator with its inherent steady-state RF operation we propose a disturbance rejection control scheme that takes the process disturbance explicitly into account. In particular, we analyze the contribution of RF noise to the development of electron beam instabilities and then use this knowledge in the subsequent beam-based feedback controller design. As a result, the control objective can be reformulated in terms of the H2 mixed-sensitivity problem, thus setting the goal toward an optimal control. Accordingly, this speed talk will briefly summarize the latest results as well as highlight the next steps.

Speaker: Mr Andrei Maalberg (Helmholtz-Zentrum Dresden-Rossendorf)

Slides 20200921_amaalberg_ard_slides.pdf

33 Data Acquisition and Analysis for the EuXFEL Optical Synchronization System (Speedtalk)

The optical synchronization system for European XFEL provides few femtosecond ultra-stable timing synchronization for accelerator subsystems and experiments. It will be the first accelerator subsystem at EuXFEL to receive an extensive data acquisition system to capture all status and operation relevant system parameters available in the DOOCS control system for uninterrupted multi-year time periods. The collected data will serve as a basis for intelligent algorithm design on a subsystem level used to improve system performance and study system aging and enable predictive maintenance.

Speaker: Mr Maximilian Schütte (DESY)

Slides 2020-09-24_Data_Acquisition_and_Analysis_for_the_EuXFEL_Optical_Synchronization_System_(ARD_ST3_Workshop).pdf

34 Modern FMC/FMC+ Carrier and IO Solutions in MicroTCA.4

Introduction of the next generation FMC/FMC+ carrier and IO controller AMC boards in MicroTCA

Speaker: Sven Stubbe (DESY)

Slides 2020-09-24_modern_fmc_and_io.pdf

35 Timing and Control Impacts on RF power at FLUTE

At the Ferninfrarot Linac und Test-Experiment (FLUTE) a regular operation with electron beam in the first section, up to 7 MeV, was achieved. For time resolved experiments the accelerating field amplitude and phase in the RF gun needs to be stable to better than 0.1%. At FLUTE a high influence of the 50 Hz AC-line power was observed and investigated. Utilizing the MRF timing distribution and the DESY LLRF system, the noise on the RF power is reduced and will be presented in this contribution.

Speaker: Mr Thiemo Schmelzer (Karlsruhe Intitute of Technology (KIT))

Slides 2020-09-ARD-ST3_speedtalk_Schmelzer.pdf

36 Discussion

16:25 Closer & Farewell