Non-interceptive Beam Diagnostics in a H− Linac During Operations Using Laser Comb and Virtual Slit
Y. Liu, W. Blokland
ORNL, Oak Ridge, Tennessee, USA
Several novel techniques have been recently developed for laser wire based non-interceptive H− beam diagnostics. A laser comb ¿ ultrashort laser pulses with macropulse structure ¿ was implemented and used for measuring time-resolved profiles/emittances from a single scan. A virtual slit technique was demonstrated for the precise measurement of short bunches formed in the superconducting linac. Both techniques have been applied to measuring parameters of neutron production H− beam at the linac of the Spallation Neutron Source. Key components in the implementation and operation of the laser comb and virtual slit will be described. Applications of the measurement results to the accelerator physics study will also be discussed.
Design and Study of Cavity Quadrupole Moment and Energy Spread Monitor
37
Q. Wang, Q.Y. Dong, L.T. Huang
DICP, Dalian, Liaoning, People’s Republic of China
Q. Luo
USTC/NSRL, Hefei, Anhui, People’s Republic of China
A nondestructive method to measure beam energy spread using the quadrupole modes within a microwave cavity is proposed. Compared with a button beam position monitor (BBPM) or a stripline beam position monitor (SBPM), the cavity monitor is a narrow band pickup and therefore has better signal-to-noise ratio (SNR) and resolution. In this study, a rectangular cavity monitor is designed. TM220 mode operating at 4.76 GHz in the cavity reflects the quadrupole moment of the beam. The cavity plans to be installed behind a bending magnet in Dalian Coherent Light Source (DCLS), an extreme ultraviolet FEL facility. In this position, the beam has a larger dispersion, which is beneficial to measure the energy spread. A quadrupole magnet, a fluorescent screen, and a SBPM with eight electrodes is installed near the cavity for calibration and comparison. The systematic framework and simulation results are also discussed in this paper.
First Direct Measurement of Electron and Positron Bunch Characteristics during Positron Capture Process at the Positron Source of the SuperKEKB B-Factory
146
T. Suwada
KEK, Ibaraki, Japan
Electron (e-) and positron (e+) bunch characteristics were directly measured for the first time using wideband beam monitors (WBMs) and a detection system at the e+ source of the SuperKEKB B-factory. Both secondarily-generated e- and e+ bunches after the e±production target were clearly identified in their dynamical capture process at locations of the WBMs under two-bunch acceleration scheme. Not only the longitudinal but also transverse bunch characteristics, the time intervals between the e- and e+ bunches, the bunch lengths, transverse bunch positions, and bunch charges were simultaneously separately measured for each bunch as functions of the capture phase to investigate their dynamical capture process. The results show that quite symmetric dynamical behaviors for the e- and e+ bunch characteristics were clearly observed. The new WBMs open up a new window for direct measurements of both the e- and e+ bunches during their dynamical capture process and in the optimization procedure of the e+ bunch intensity in multidimensional parameter spaces at any e+ sources. The historical backgrounds for introducing and implementing the new WBMs are also described in this report.
Sub-20 fs Synchronization Between Mode-Locked Laser and Radio Frequency Signal
151
J.G. Wang, B. Liu, W. Wu
SARI-CAS, Pudong, Shanghai, People’s Republic of China
The femtosecond synchronization and distribution system of the Shanghai soft X-ray free-electron laser facility (SXFEL) and Shanghai high repetition rate XFEL and extreme light facility (SHINE) are based on the optical pulse trains generated by passively mode-locked lasers. The passively mode-locked laser has ultralow noise in the high offset frequency (<5 fs, [1 kHz- 1 MHz]). In this paper, we report precise synchronization of the low-noise passively mode-locked laser to the radio frequency (RF) master oscillator. RF-based phase-locked loop scheme, the absolute jitter of the phase-locked passively mode-locked laser is less than 20 fs integrated from 10 Hz up to 1 MHz.
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Use of the ISAC-II Flight Time Monitors toward Automated Tuning
195
S. Kiy, P.M. Jung, T. Planche, O. Shelbaya, V.V. Verzilov
TRIUMF, Vancouver, Canada
A time-of-flight measurement system has been in use at ISAC-II since 2006 for the phasing of cavities and accurate ion beam velocity measurements across the nuclear chart. This system is heavily relied upon as the primary energy-time domain diagnostic downstream of the ISAC-II linac. Ongoing High Level Applications (HLA) development at TRIUMF has enabled the use of methods that are being applied to these measurements - both for processing and automation of data acquisition. An update will be provided on operational experience with the system over the past 10 years including its recent re-calibration and error analysis. A brief summary of the current HLA framework will be given, including a database for beam measurements and the ability to carry out sequential measurement processes. Finally, the way in which these developments enable beam-based calibration of cavity parameters and a shift to model-based tuning methods is discussed.
Recording Series of Coherent Thz Pulse Shapes with Up to 88 MHz Repetition Rate at Soleil, Using Photonic Time-Stretch
C. Szwaj, S. Bielawski
PhLAM/CERLA, Villeneuve d’Ascq, France
J.B. Brubach, M. Labat, L. Manceron, P. Roy
SOLEIL, Gif-sur-Yvette, France
C. Evain, M. Le Parquier, E. Roussel
PhLAM/CERCLA, Villeneuve d’Ascq Cedex, France
Funding:ANR/DFG ULTRASYNC, CEMPI LABEX, CPER Photonic for Society Recording THz signals in single-shot is required in various accelerator applications, including real-time studies of electron bunch shapes, and user-applications employing coherent THz synchrotron radiation. For this purpose, many accelerator facilities have implemented laser-based measurement systems known as electro-optic detection. This consists of ¿imprinting¿ the unknown terahertz waveform on a shot laser pulse, that is subsequently analyzed. Few years ago a new variant of this method, time-stretch electro-optic detection [1,2], has been introduced with the aim to cope with high repetition-rate machines. We present the current record in repetition rate (up to 88 MHz), that has been obtained at the AILES beamline of the SOLEIL facility. We also present the projects aiming at reaching long recording windows and/or high bandwidth [3] using time-stretch, as well as the expected fundamental trade-offs linked to the quest for high repetition rate. [1] E. Roussel et al., Scientific reports 5.1 (2015): 1-8. [2] S. Bielawski et al., Scientific reports 9.1 (2019): 10391. [3] E. Roussel et al., Light: Science & Applications 11.1 (2022): 14.
Bunch Length Measurement System Downstream the Injector of the S-DALINAC
200
A. Brauch, M. Arnold, M. Dutine, J. Enders, R. Grewe, L.E. Jürgensen, N. Pietralla, F. Schließmann, D. Schneider
TU Darmstadt, Darmstadt, Germany
Funding:Work supported by the State of Hesse within the Cluster Project ELEMENTS (Project ID 500/10.006) and by DFG (GRK 2128 AccelencE). The S-DALINAC is a thrice recirculating electron accelerator for high resolution electron scattering experiments with a continuous-wave beam at a frequency of 2.9972(1) GHz. Short bunches are crucial to enable tuning of the machine for operation as an energy-recovery linear accelerator* **. Currently, measurements of this beam parameter are accomplished by using the radio-frequency zero-crossing method: here, a momentum spread chirp is induced and the transverse beam profile in a downstream located dispersive section is measured with a scintillating screen providing an upper limit of the bunch length. Since this method is time consuming, a new setup for these measurements using a streak camera is developed. Optical transition radiation from an aluminum-coated Kapton target is used to map the bunch length information to a light pulse which enables an accurate measurement compared to a scintillating screen. The light pulse can then be evaluated with the streak camera by projecting its length onto the transverse dimension on a phosphor screen. This contribution will present the current status of the measurement setup as well as its design and properties. *Michaela Arnold et al., Phys. Rev. Acc. Beams 23, 020101 (2020). **F. Schliessmann et al., Nat. Phys. 19, 597-602 (2023).
Intermediate Frequency Circuit Components for Integration of on-Chip Amplifier With THz Detectors
204
R. Yadav, S. Preu
IMP, TU Darmstadt, Darmstadt, Germany
A. Penirschke
THM, Friedberg, Germany
Funding:The work is supported by the German Federal Ministry of Education and Research (BMBF) under contract no. 05K22RO1 for applications at HZDR, Dresden, LAS at KIT and DELTA at TU Dortmund. The Zero-Bias Schottky Diode (ZBSD) and field effect transistor (TeraFET) based Terahertz (THz) detectors be- come more and more important for beam diagnosis and alignment at THz generating accelerator facilities. The roll- off factor of the detectors at higher THz frequencies requires wide-band amplifiers to enhance the IF signal from a few µW to nW well above the noise floor of the following post detection electronics. Connecting external amplifiers to the detectors via rf cables would enhance the signal losses even further and degrade the signal to noise ratio (SNR). In order to maximize the SNR, it is necessary to have on-chip amplifier integrated in the intermediate frequency (IF) circuit of the detector in the same housing. In this work, we present the design and parametric analysis of components for transition to an IF circuit, which will be integrated in the ZBSD and TeraFET on chip with amplifier in the same housing. The design analysis has been done to find the optimal parameters. The broader IF circuit will enhance the detector resolution to capture pulses in the picosecond range with the help of fast post detection electronics. [*] R. Yadav et al., doi:10.3390/s23073469 [**] S. Preu et al., doi:10.1109/TTHZ.2015.2482943 [***] A. Penirschke et al., doi:10.1109/IRMMW-THz.2014.6956027
Geometry Study of an RF-Window for a GHz Transition Radiation Monitor for Longitudinal Bunch Shape Measurements
209
S. Klaproth, A. Penirschke
THM, Friedberg, Germany
H. De Gersem
TEMF, TU Darmstadt, Darmstadt, Germany
R. Singh
GSI, Darmstadt, Germany
Funding:This work is supported by the German Federal Ministry of Education and Research (BMBF) under contract no. 05P21RORB2. Joint Project 05P2021 - R&D Accelerator (DIAGNOSE) GHz transition radiation monitors (GTRs) can be used to measure longitudinal beam profiles even for low ß beams. In comparison to traditional methods e.g., Fast Faraday Cups (FFCs) and Feschenko monitors, GTRs are a non-destructive measurement method and are able to resolve bunch-by-bunch longitudinal profiles at the same time. In our case, we plan to measure the transition radiation outside the beam line through an RF-window with an 8 GHz broad band antenna. At the border of the RF-window the transition radiation is partially reflected propagating in the beam line backwards. In this contribution, we show a study of different geometries to suppress reflections generated at the transition to the RF-window. For higher permittivity the strength of these reflections becomes stronger, simultaneously reducing the measurable signal strength at the antenna. Secondly the RF-window material must be UHV usable and should be durable like Alumina or Peek.
First Measurements of an Electro-Optical Bunch Arrival-Time Monitor Prototype with PCB-Based Pickups for ELBE
214
B.E.J. Scheible, A. Penirschke
THM, Friedberg, Germany
W. Ackermann, H. De Gersem
TEMF, TU Darmstadt, Darmstadt, Germany
M.K. Czwalinna, T.A. Nazer, H. Schlarb, S. Vilcins
DESY, Hamburg, Germany
M. Freitag, M. Kuntzsch
HZDR, Dresden, Germany
Funding:This work is supported by the German Federal Ministry of Education and Research (BMBF) under Contract No. 05K19RO1 and 05K22RO2. A vacuum sealed prototype of an electro-optical bunch-arrival-time monitor has been commissioned in 2023. It comprises of a pickup-structure and a low-pi-voltage ultra-wideband traveling wave electro-optical modulator. The stainless-steel body of the pickup structure is partially produced by additive manufacturing and comprises four pickups as well as an integrated combination network on a printed circuit board. This novel design aims to enable single-shot bunch-arrival-time measurements for electron beams in free-electron lasers with single-digit fs precision for low bunch charges down to 1 pC. The theoretical jitter charge product has been estimated by simulation and modeling to be in the order of 9 fs pC. The new prototype is tailored for validation experiments at the ELBE accelerator beamline. In this contribution first measurement results are presented.
Diversity Enhanced Electro-Optic Sampling at EuXFEL
B. Steffen, M.K. Czwalinna
DESY, Hamburg, Germany
S. Bielawski, Q. Demazeux, C. Evain, E. Roussel, C. Szwaj
PhLAM/CERLA, Villeneuve d’Ascq, France
Electro-optical detection has proven to be a valuable technique to study temporal profiles of THz pulses with pulse durations down to femtoseconds. Recently, a numerical reconstruction strategy called DEOS [1] (Diversity Electro-Optical Sampling) proved to be much more efficient in retrieving ultrafast input signals. First tests at the European X-ray FEL (EuXFEL) in Hamburg show a 200 fs temporal resolution over more than 10 ps recording length. This technique, however, requires to measure both orthogonal polarizations of the sampling laser pulse simultaneously. Further adaptations to the existing design of the compact EOD bunch length monitor [2] are needed to fully implement the new measurement strategy, which will be presented in this paper. [1] E. Roussel, C. Szwaj, C. Evain, B. Steffen, C. Gerth, B. Jalali and S. Bielawski, Light Sci. Appl., vol. 11, p. 14, 2022. doi:10.1038/s41377-021-00696-2 [2] B. Steffen, Ch. Gerth, M. Caselle, M. Felber, T. Kozak, D. R. Makowski, U. Mavric, A. Mielczarek, P. Peier, K. Przygoda, and L. Rota, Sci. Instrum., vol 91, p. 045123, 2020. doi:10.1063/1.5142833
Design and Test of a Prototype 324 MHz RF Deflector in the Bunch Shape Monitor for CSNS-II Linac Upgrade
219
W.L. Huang, X.J. Nie
IHEP CSNS, Guangdong Province, People’s Republic of China
M.Y. Liu, X.Y. Liu, Y.F. Sui
IHEP, Beijing, People’s Republic of China
Q.R. Liu
UCAS, Beijing, People’s Republic of China
Funding:Natural Science Foundation of Guangdong Province, 2021A1515010269 National Natural Science Foundation, 11475204 During the upgrade of linac in CSNS-II, the beam in-jection energy will increase from 80.1MeV to 300MeV and the beam power from 100kW to 500kW. A com-bined layout of superconducting spoke cavities and ellip-tical cavities is adopted to accelerate H− beam to 300MeV. Due to a ~10ps short bunch width at the exit of the spoke SC section, the longitudinal beam density dis-tribution will be measured by bunch shape monitors using low energy secondary emission electrons. As the most important part of a bunch shape monitor, a prototype 324MHz RF deflector is designed and tuned on the basis of a quasi-symmetric λ/2 325MHz coaxial resona-tor, which was fabricated for the C-ADS proton accelera-tor project. Preliminary parameters of the bunch shape monitor are presented. Simulation of the RF deflector and test results in the laboratory are described and analysed.
The Upgrade of the Light Pulse Picking System at HLS-II
J. Wang, P. Lu, B.G. Sun, L.L. Tang, Y.K. Zhao, T.Y. Zhou, Z.R. Zhou
USTC/NSRL, Hefei, Anhui, People’s Republic of China
Funding:National Natural Science Foundation of China under Grant 12075236 In 2009, the light pulse picking system was built to pick a single synchrotron radiation light pulse from 45 light pulses so that it can be used for researching the longitudinal bunch characteristics at HLS. The optical system was operating well, but the optical pulse picking width was 9.8 ns, which is greater than the bunch interval of 4.9 ns. Therefore, the signal-to-noise ratio of the system is not good enough. The HLS-II light source refers to the machine upgrade project of HLS in 2014. After that, the longitudinal beam characteristics was changed. Therefore, the synchrotron light pulse picking system with better performance has been developed to meet the needs of beam diagnosis and longitudinal beam dynamics research.
Longitudinal Parameter Measurement System Based on Time-Frequency Domain Joint Analysis
HS. Wang, Y.M. Zhou
SSRF, Shanghai, People’s Republic of China
Y.B. Leng
USTC/NSRL, Hefei, Anhui, People’s Republic of China
X. Yang
UCAS, Beijing, People’s Republic of China
This paper proposes a novel technique for measuring longitudinal bunch length by performing spectral analysis on the beam signals to extract the bunch length information for each bunch and each turn. A high-speed oscilloscope is used to capture original button signal with more than 7000 turns information and an offline Python script is used to retrieve bunch length and phase information. A streak camera is used to calibrate the transfer function of the acquisition system. Experiments were carried out at the Shanghai Synchrotron Radiation Facility and the Hefei Light Source by capturing the electrode signals with an oscilloscope during single bunch injection and harmonic cavity tuning in the storage ring. The calibrated longitudinal bunch length measurement system yielded favorable results, with a larger dynamic range and higher time resolution compared to the streak camera. In the future, the system has the potential to be transplanted into a processor to achieve online longitudinal beam measurement for each bunch.
Femtosecond Relativistic Electron Bunch Compression and Diagnosis using Terahertz-driven Resonators
Y. Xu, K. Fan, Z. Liu, Y. Song, C.-Y. Tsai
HUST, Wuhan, People’s Republic of China
L.X.F. Li
Private Address, Wuhan, People’s Republic of China
Funding:This work is supported by the National Natural Science Foundation of China (12235005) and the Science and Technology Project of State Grid (5400-202199556A-0-5-ZN). Ultrafast electron beams lengthening and time jitter severely degrade the temporal resolution in electron-laser applications, such as ultrafast electron diffraction (UED). In recent years, terahertz-driven devices have shown great potential in beam manipulation and diagnostics. This paper reports an all-optical method for compressing and characterizing a 3 MeV electron beam using single-cycle terahertz radiation. A THz buncher longitudinally compresses the electron beams, and the resulting shortest bunch length and arrival time are measured using a transverse THz field in a downstream terahertz slit. Particle tracking simulation shows that the bunch is compressed more than 13 times from 54 fs to 4 fs, and the arrival time jitter is reduced from 100 fs to 21 fs. This method effectively manipulates the beam longitudinal phase space, compresses the beam length, and suppresses the time jitter. It is expected to significantly impact ultrafast science and be applied in other accelerator applications.
Development of Stripline Fast Faraday Cup at MEBT of RAON
J.W. Kwon, G.D. Kim, H.J. Woo
IBS, Daejeon, Republic of Korea
E.H. Lim
Korea University Sejong Campus, Sejong, Republic of Korea
RAON (Rare isotope accelerator complex for On-line experiment) is an accelerator that accelerates heavy ions such as uranium, oxygen, and protons. In the MEBT section, the ion beam is accelerated and focused by RFQ, has bunch structure with a period of 81.25 MHz, and has an energy of 507 keV/u. To measure the shape of a beam, the transverse and longitudinal profiles should be obtained using beam diagnostic device. To measure bunch lengths of less than 1 ns, 50 Ω matched stripline type fast faraday cup was fabricated and the signal was amplified by a 4 GHz broadband signal amplifier with a gain of 42 dB. The amplified signal was measured using an oscilloscope with a high sampling frequency of 25 GSPS and a wide frequency bandwidth of 4 GHz. The developed fast faraday cup was installed at the end of the MEBT in front of SCL3. This poster describes the design of a stripline fast faraday cup and the results of measuring the bunch length at a MEBT section using Ar 9+ at 30 uA current.
Development of the RF Phase Shifter with Femtosecond Time Delay Resolution for the PAL-XFEL Laser System
222
D.C. Shin, H.-S. Kang, G. Kim, C.-K. Min, G. Mun
PAL, Pohang, Republic of Korea
We introduce the RF Phase Shifter (RPS) developed in the Pohang Accelerator Laboratory X-ray Free-Electron Laser (PAL-XFEL) to control the timing of optical laser system. This equipment is designed to finely adjust the timing of laser pulses with femtosecond scale by manipulating the phase of the RF reference using a couple of Direct Digital Synthesizer (DDS) devices. Furthermore, it is designed with low phase noise and low phase drift features in order to minimize the impact on the system in an open-loop operation. Currently these units are installed at the Injection site, Hard X-ray and Soft X-ray Beamline. They are implemented for the feedback control of the photocathode gun phase at the Injector and for the use in pump-probe experiments at the Beamlines. This paper describes the design, fabrication, and experimental results of the RPS, as well as its usage status at PAL-XFEL.
Characterisation of Cherenkov Diffraction Radiation Using Electro-Optical Methods
226
A. Schlögelhofer, T. Lefèvre, S. Mazzoni, E. Senes
CERN, Meyrin, Switzerland
L. Duvillaret
KAPTEOS, Sainte-Helene-du-Lac, France
A. Schlögelhofer
TU Vienna, Wien, Austria
The properties of Cherenkov diffraction radiation (ChDR) have been studied extensively during the recent years to be exploited for non-invasive beam diagnostic devices for short bunches. The dependence of charge and the influence of the bunch form factor on the coherent part of the radiated spectrum have been demonstrated and studied in the past. However, the actual field strength of coherent ChDR as well as its study in time domain need further investigation. In this contribution we are using electro-optical techniques to investigate and quantify these parameters. The electro-optical read-out brings the advantage of high bandwidth acquisition and insensitivity to electromagnetic interference, whereas at the same time a large fraction of the acquisition setup can be installed and operated outside of the radiation controlled areas. We will present experimental results from the CLEAR facility at CERN as well as simulations of the peak field of the temporal profile of beam-generated ChDR pulses.
Bunch Compressor Monitors for the Characterization of the Electron Bunch Length in a Linac-Driven FEL
235
G.L. Orlandi
PSI, Villigen PSI, Switzerland
The lasing performance of a Free Electron Laser (FEL) strongly relies on a precise characterization of the electron bunch length and on the control and stabilization of the bunch compression settings of the machine under normal user operations. In a FEL driver linac, the so-called Bunch Compressor Monitors (BCMs) normally ensure the non-invasive monitoring of the electron bunch length. BCMs, being sensitive to the temporal coherent threshold of the radiation energy emitted by the electron beam crossing the last dipole of a magnetic chicane or a holed diffraction screen just downstream, can provide a bunch length dependent signal resulting from the integration of the detected radiation pulse energy over the acceptance frequency band of the detector. Thanks to the non-invasiveness, BCMs are primary diagnostics in a FEL to stabilize the bunch compression by feeding back the RF settings of the accelerating structure. In this contribution, we present a formal method to determine an absolute measurement of the electron bunch length from the analysis of a BCM signal (*). (*) G.L. Orlandi, Absolute and non-invasive determination of the electron bunch length in a Free Electron Laser using a Bunch Compressor Monitor, https://doi.org/10.48550/arXiv.2305.17042, https://doi.org/10.21203/rs.3.rs-3228455/v1
Microbunching of Thermionic Cathode RF Gun Beams in the Advanced Photon Source S-Band Linac
240
J.C. Dooling, A.R. Brill, N. Kuklev, I. Lobach, A.H. Lumpkin, N. Sereno, Y. Sun
ANL, Lemont, Illinois, USA
Funding:Work supported by the U.S. D.O.E.,Office of Science, Office of Basic Energy Sciences, under contract number DE-AC02- 06CH11357. We report on measurements of beams from thermionic cathode (TC) rf guns in the Advanced Photon Source S-Band Linac. These measurements include the macropulse out of both new and existing TC guns as well as the observation of microbunching within the micropulses of these beams. A gun chopper limits the macropulse FWHM duration to the 10-ns range. Our objectives were to analyse the new TC gun and investigate microbunching within a TC-rf-gun-generated beam. Our diagnostics elucidated longitudinal beam structures from the ns to the fs time scales. Coherent transition radiation (CTR) interferometers responding to far-infrared wavelengths were employed after each compression stage to provide the autocorrelations of the sub-ps micropulse durations. The first compression stage is an alpha magnet and the second a chicane. A CCD camera was used to image the beam via optical transition radiation from an Al screen at the end of the linac and also employed to measure coherent optical transition radiation (COTR) in the visible range. The COTR diagnostic observations, implying microbunching on a fs time scale, are presented and compared with a longitudinal space-charge impedance model.
A Hybrid Approach to Upgrade Hardware for the Proton Storage Ring Fast Kicker
250
T. Ramakrishnan, J.I. Duran, H.A. Watkins
LANL, Los Alamos, New Mexico, USA
Funding:Work supported by the U.S. Department of Energy, contract no. 89233218CNA000001. LA-UR-23-25123 The Los Alamos Neutron Science Center (LANSCE) Proton Storage Ring (PSR) needs precise timing to ensure successful extraction of the bunched protons. The current control system¿s hardware is obsolete and unmaintainable. The task was to replace the 1980¿s era CAMAC control and timing system for the PSR extraction kickers. This included a system which halts charging of the kickers after a duration without firing to prevent equipment damage. A hybrid approach was taken to integrate a Berkeley Nucleonics Corporation (BNC) pulse generator that was controlled by a soft input/output controller (IOC) and National Instrument compact Reconfigurable Input/Output (cRIO) IOC. This allowed for flexibility and modularity of the software and hardware development. This approach built the framework to streamline robust deployment of hybrid systems and develop a solution for upgrades of other LANSCE kickers.
Proposal for a Low-Cost Wakefield Deflector for CW X-ray FEL Operation
D.K. Bohler, P. Krejcik, A.A. Lutman, A. Novokhatski
SLAC, Menlo Park, California, USA
SLAC National Accelerator Laboratory is undertaking a project to develop a dielectric wakefield deflector with the goal of enhancing Free-Electron Laser (FEL) operational modes and providing comprehensive bunch diagnostics. The project aims to re-establish and optimize the Fresh-slice operation modes in the recently upgraded Soft X-ray Line (SXR) of the LCLS, a scheme noted for its success in delivering femtosecond, high-power double-pulses within the SXR wavelength range and contributing significantly to research published in high-impact journals. The novel wakefield deflector design incorporates an L-shaped bar and a dielectric wakefield deflector using an anodized aluminum bar, drawing from the successful approaches of teams at DESY and PSI. This single straight, rectangular aluminum L-shaped bar, coated with an aluminum oxide dielectric layer, represents a marked improvement over previous corrugated metal jaw designs. Furthermore, this project explores the potential of this passive streaker as a diagnostic tool for electron bunch phase space, promising exciting advancements in the field of accelerator technologies
M.W. Bruker, J.M. Grames, J. Guo, J. Musson, S.A. Overstreet, G.-T. Park, T.E. Plawski, M. Poelker, R.A. Rimmer, H. Wang, C.M. Wilson, S. Zhang
JLab, Newport News, Virginia, USA
M.H. Pablo, B.F. Roberts, D. Speirs
Electrodynamic, Albuquerque, New Mexico, USA
Funding:Work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177. Multi-Harmonic driver development supported by SBIR DE-SC0020566. A harmonically resonant kicker cavity designed for beam exchange in a circulator cooler* was built and successfully tested at the Upgraded Injector Test Facility (UITF) at Jefferson Lab. This type of cavity is being considered for the injection scheme of the Rapid Cycling Synchrotron at the Electron-Ion Collider, where the spacing of neighboring bunches demands very short kicks. Operating with five transversely deflecting modes simultaneously that resonate at 86.6 MHz and consecutive odd harmonics thereof, the prototype cavity selectively deflects 1 of 11 electron bunches while leaving the others unperturbed. An RF driver was developed to synthesize phase- and amplitude-controlled harmonic signals and combine them to drive the cavity while also separating the modes from a field-probe antenna for RF feedback and dynamic tuning. Beam deflection was measured by sweeping the cavity phase; the deflection waveform agrees with expectations, having sub-nanosecond rise and fall times. No emittance increase is observed. Harmonically resonant cavities like the one described provide a new capability for injection and extraction at circulators and rings. * G.T. Park et al., "Beam exchange of a circulator cooler ring with an ultrafast harmonic kicker", Phys. Rev. Accel. Beams 24, 061002
Online Bunch Length Monitoring for Storage Ring using a Fast Photodiode
G. Hahn, C. Kim, D. Kim
PAL, Pohang, Republic of Korea
J.-G. Hwang
HZB, Berlin, Germany
W.J. Song
POSTECH, Pohang, Republic of Korea
Providing bunch lengths and a filling pattern of the bunch train in real-time is one of the important challenges in beam instrumentation of the 3rd generation light source. In particular, the time length and intensity information of the synchrotron light is useful to beamlines and their users who perform time-resolved experiments. We developed an online monitoring system that can measure bunch lengths and a filling pattern simultaneously by directly observing the synchrotron radiation with a picosecond-resolution photodiode and high input-analog-bandwidth digitizer. A Gaussian deconvolution method to restore the original waveform of synchrotron radiation using the system impulse response function was developed and adopted. In this paper, we present the experimental setup, signal processing method, and several machine study results in detail using the fast photodiode in the PLS-II
E. Mansten, S. Thorin
MAX IV Laboratory, Lund University, Lund, Sweden
The first streaked electrons in the new MAX IV Transverse deflecting cavity (TDC) were just achieved. The TDC consists of two 3 m long transverse deflecting RF structures, operating at S-band, with possibility to adjust the polarization of the deflecting fields. The TDC will use an energy doubling system (SLED) to increase the field in the cavities and along with a large beta function through the structure and a small beta focus at the detector, this will produce a time resolution of 1 fs. The first results of measurements are believed to be achieved within the next few months.
THz Antenna-Coupled Zero-Bias Schottky Diode Detectors for Particle Accelerators
301
R. Yadav, S. Preu
IMP, TU Darmstadt, Darmstadt, Germany
J.M. Klopf, M. Kuntzsch
HZDR, Dresden, Germany
A. Penirschke
THM, Friedberg, Germany
Funding:The work is supported by the German Federal Ministry of Education and Research (BMBF) under contract no. 05K22RO1 for applications at HZDR, Dresden, LAS at KIT and DELTA at TU Dortmund. Semiconductor-based broadband room-temperature Terahertz (THz) detectors are well suitable for beam diagnosis and alignment at accelerator facilities due to easy handling, compact size, no requirement of cooling, direct detection and robustness. Zero-Bias Schottky Diode (ZBSD) based THz detectors are highly sensitive and extremely fast, enabling the detection of picosecond scale THz pulses. This contribution gives an overview of direct THz detector technologies and applications. The ZBSD detector developed by our group has undergone several tests with table-top THz sources and also characterized with the free-electron laser (FEL) at HZDR Dresden, Germany up to 5.56 THz. In order to understand the rectification mechanism at higher THz frequencies, detector modelling and optimization is essential for a given application. We show parametric analysis of a antenna-coupled ZBSD detector by using 3D electromagnetic field simulation software (CST). The results will be used for optimization and fabrication of next generation ZBSD detectors, which are planned to be commissioned at THz generating FEL accelerator facilities in near future. [1] R. Yadav et al., doi:10.3390/s23073469 [2] M. Hoefleet al., doi:10.1109/IRMMW-THz.2013.6665893 [3] R. Yadav et al., doi:10.18429/JACoW-IPAC2022-MOPOPT013
Beamline for Time Domain Photon Diagnostics at the Advanced Photon Source Upgrade
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K.P. Wootton, W.X. Cheng, G. Decker, N. Sereno, F. Westferro
ANL, Lemont, Illinois, USA
Funding:This research used resources of the Advanced Photon Source, operated for the U.S. Department of Energy Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357. Time domain photon diagnostics are proposed for electron beam characterisation and operation of the Advanced Photon Source Upgrade storage ring. In the present work, we present updated status on the time-domain X-ray and visible photon diagnostic beamline for the Advanced Photon Source Upgrade. We outline design influences leading to the proposed beamline layout, in particular long-term maintenance and commonality with other beamlines at the Advanced Photon Source.
