Pile-Up Effect of Cold Button BPMs in the European XFEL Accelerator

The European XFEL facility is in operation with a maximum of 2700 bunches in one train. The highest bunch repetition rate is 4.5 MHz; this corresponds to a minimum time separation of 222 ns. The measurement of the beam properties for each bunch in a train is required. Therefore the beam position monitor (BPM) system needs to separate the signals from each bunch. All BPM types (button, re-entrantand cavity) fulfill this requirement except a few button BPMs installed inside of the cold accelerator module, where Pile-Up from the train can be observed. To identify the cause of this effect we measured the S-parameters during a shutdown of the accelerator, compared it with a similar BPM atthe FLASH accelerator but located in a warm section and finally measured the spectrum of the button signal during beam operation. As a result, resonances were found at about2.46 GHz with relatively high quality factor that remains within the frequency range accepted by the electronics

Development of a New BPM Electronic System for the PETRA Pre-Accelerator Chain

There is a large range of bandwidth needed for the BPM electronic for the Petrapreaccelerators. The bunch length varied from ns to ps range. Also a new bunch burstmode is request for Petra IV first turn operation.The new BPM electrons is developed as a universal peakdetector hardware in an mtca.4environment.Automatic adjusted Delay lines or 2x2 cross point switch technique will be tested for selfcalibration.The goal is a universal mtca.4 based electronic for button BPMs.The limitation of this detector electronic is the bunch space of at least 100ns.●Refurbishment of existing electronic●Uniformed Hard and Software●Mtca.4 Hardware●Doocs Server●Self calibrated●Designed for Petra4 requirement

Beam Position Monitoring of Multi-bunch Electron Beams at the FLASH Free Electron Laser

The superconducting FLASH user facility (Free electron LASer in Hamburg) accelerates 10 electron bunch trains per second, which are mostly used to produce high brilliance XUV and soft X-ray pulses. Each train usually contains up to 600 electron bunches with a typical charge between 100 pC and 1 nC and a minimum bunch spacing of 1 us. Various types of beam position monitors (BPM) are built in three electron beam lines, having a single bunch resolution of 2-100 um rms. This paper presents multi-bunch position measurements for various types of BPMs and built in at various locations. The dependency of the resolution on the beam offset is also shown

High Resolution and Low Charge Button and Strip-Line Beam Position Monitor Electronics Upgrade at FLASH

Historically the FLASH (Free Electron Laser in Hamburg) facility at DESY (Deutsches Elektronen-Synchrotron)in Germany has foreseen operation in a charge range from1 nC-3 nC for which a VME based BPM (Beam Position Monitor) system has been in operation since 2005 with a later upgrade to lower charges. In the past few years the standard machine operation settled at a few hundreds ofpC with a tendency to smaller charges down to 100 pC and less. The performance of the BPM system at charges below300 pC was in many locations along the machine unsatisfactory,making the operation of the linac more unstableand less reliable. Therefore a new BPM electronic system based on the utca (Micro Telecommunication ComputingArchitecture) for physics MTCA.4 standard has been developed to overcome the limitations of the old electronics and has already been successfully in operation in FLASH 2. A substantially improved version of the RF (radio frequency)front-end and digital electronics/firmware has been developed in 2016 and tested successfully. The peak detector electronics have been extended to a double peak detection in four channels and the fully customized Firmware is working machine synchronous. In summer 2017 all old button and strip-line BPM electronics have been replaced with the newtype. This paper summarizes the features and performance of the new BPM system, compares the beam jitter free resolution of the old and new BPM system and highlights its high single shot resolution of better than 10 $\mu$m rms at acharge of 15 pC

Energy Beam Position Monitor Button Array Electronics for the European XFEL

The European XFEL(X-Ray Free Electron Laser) at DESY(Deutsches Elektronen-Synchrotron) in Hamburg/Schenefeld started commissioning in early 2017. Before the pulsed electron beam is accelerated to its final energy of 14 GeV, the energy of the bunch can be compressed in three bunch compression chicanes at 130 MeV, 700 MeV and 2400 MeV. The vacuum chamber in these sections is tapered from 40 mm round beam pipe to a 40 cm rectangular shaped vacuum section. A custom made button array type of BPM(Beam position Monitor) is installed in this section with 26 button electrode feed-throughs. The analog and digital readout electronics for this monitor and the first experience with the calibration and operational aspects of this system are presented in this poster

Development Status and Performance Studies of the New MicroTCA Based Button and Strip-line BPM Electronics at FLASH 2

The FLASH (Free Electron Laser in Hamburg) facility at DESY (Deutsches Elektronen-Synchrotron) in Germany has been extended by the new undulator line FLASH 2 providing twice as many experimental stations for users in the future [1]. After the acceleration of the electron bunch train up to 1.2 GeV in FLASH, a part of the beam can be kicked into FLASH 2, while the other is going to the old undulator line of FLASH 1. The commissioning phase started in early 2014 and continues parasitically during user operation in FLASH 1. One key point during first beam commissioning is the availability of standard diagnostic devices such as Beam Position Monitors (BPMs) [2]. In the last couple of yearsnew electronics for button and strip-line BPMs have been developed, based on the MTCA.4 standard [3–6]. This new Low Charge BPM (LCBPM) system is designed to work with bunch charges as small as 100 pC in contrast to the old systems at FLASH initially designed for bunch charges of 1 nC and higher. This paper summarizes the development status of the new BPM system and discusses the results ofresolution studies of the BPM system

First Tests with the Self-triggered Mode of the New MicroTCA-based Low-charge Electronics for Button and Stripline BPMs at FLASH

The FLASH facility at DESY is currently enhanced by a second beamline (FLASH2) to extend the capacity for user experiments. In addition, certain support systems like the timing system and the BPM system at the existing FLASH accelerator have been partly renewed and are now under commissioning. New button BPM electronics based on the MTCA.4 for physics standard is provided for the FLASH2 beamline and is foreseen as a replacement of the old BPM electronics at FLASH. Compared to the predecessor of the FLASH button BPM electronics, the new system has been specifically designed for low charge operation exceeding a wide dynamical charge range between 100pC and 3nC. Special provisions have been made to enable single bunch measurements in a self-triggered mode, enabling timing-system-independent measurements during commissioning and at fallback during normal operation

Cavity BPM Electronics for SINBAD at DESY

The SINBAD(Short and INnovative Bunches and Accelerators at DESY ) R&D accelerator is planned for studying new concepts for high gradient electron beam acceleration and the generation of ultra-short electron bunches. The accelerator called ARES(Accelerator Research Experiment At DESY) is composed of S-band accelerating structures. In order to achieve the goal of very short electron bunches the electron beam charges generated in the RF Gun can vary in a range from 1nC down to 500fC. In order to measure the beam position with good resolution at the small charge end of 500fC a new cavity BPM(beam position monitor) has been developed. One key component in the BPM system is the custom RF electronics to meet the resolution requirements in the entire charge range. The entire BPM system with a focus on the system design requirements and the utca based RF electronics are presented in this paper