resonance
MOPA033
Validation and countermeasures of vertical emittance growth due to crab cavity noise in a horizontal crab-crossing scheme
97
The future Electron-Ion Collider (EIC) adopts a horizontal crab crossing scheme to compensate for the geometric luminosity loss from a 25 mrad crossing angle. The crab cavity noise-induced emittance growth in the deflecting plane (horizontal for EIC) has been well studied and a feedback system is effective to suppress the growth. However, simulations also showed emittance growth in the vertical plane when the beam profile is flat at IP. In this article, we will validate this observation and propose countermeasures to this emittance growth.
Paper: MOPA033
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPA033
About: Received: 03 May 2023 — Revised: 11 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
MOPA051
Nonlinear coupling resonances in the EIC electron storage ring
140
The 18 GeV Electron Storage Ring (ESR) lattice of the Electron-Ion Collider (EIC) showed various undesirable effects in nonlinear Monte Carlo tracking, including a vertical core emittance exceeding radiation-integral predictions and a low asymptotic polarization. These problems were resolved in a newer lattice where dispersion in the solenoidal spin rotators was set to zero. Here we identify the cause of the effects as a 2nd order synchro-beta resonance which is driven by vertical dispersion in the quadrupoles of the rotators. The 5 and 10 GeV ESR lattices have small but nonzero dispersion in the rotators, and misalignments in the 18 GeV case will inevitably create some dispersion, so care must be taken that this 2nd order resonance is not excited. Zero dispersion in the spin rotators may therefore not be the best solution, and a new working point is sought that is not close to this resonance. The implications of this result on the design of the ESR – including achieving a longitudinal spin match – are explored.
Paper: MOPA051
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPA051
About: Received: 03 May 2023 — Revised: 06 May 2023 — Accepted: 11 May 2023 — Issue date: 26 Sep 2023
MOPA076
Modernization of the laser-optical system of the X-ray generator NESTOR
206
Modernization of the NESTOR hard X-ray generator storage ring for switching to the operating frequency of the accelerator of 2.856 GHz requires corresponding changes in the design of the high-frequency system, and this, in turn, leads to the need to modernize the laser-optical system. The necessary calculations were carried out to determine the new characteristics of the pulsed laser, the Fabry-Perot cavity, and the lens optical system matching the beam geometry. The obtained results confirm the possibility to use an already existing laser-optical system at a new operating frequency of the accelerator with some changes in the design.
Paper: MOPA076
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPA076
About: Received: 09 May 2023 — Revised: 10 May 2023 — Accepted: 15 Jun 2023 — Issue date: 26 Sep 2023
MOPA089
Earthquake measurements and those analysis on ir components and Belle II detector in KEK
249
We frequently experience earthquakes in Japan. Even though countermeasures against earthquake is deeply considered and well carried out, sometime troubles are occurred on facilities or experimental devices. When we focus on the relative displacement due to an earthquake, it is possible to cause damage of a beam pipe bellows or interference by disappearing tolerance between the sub-detectors. And magnet quenches have been triggered due to relative displacement of magnetic fields between three superconducting solenoids, i.e., the detector solenoid and two compensating solenoids in each final focus magnets, when earthquake occurred. So, we set acceleration sensors, the relative displacements had been measured. And also, laser distance sensors and gap sensors mounting on the final focus magnets were referred for this study. From these measurement data, characteristics of earthquakes were analyzed. Measurement acceleration data was also applied for response spectrum analysis. In this presentation, we will present the measurements and analysis results, and comparison between the measurements and the FEM calculations are shown.
Paper: MOPA089
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPA089
About: Received: 08 May 2023 — Revised: 09 May 2023 — Accepted: 20 Jun 2023 — Issue date: 26 Sep 2023
MOPA092
Estimated heat load and proposed cooling system in the FCC-ee Interaction region beam pipe
260
We discuss the beam power loss related to the heating of the beam pipe walls of the FCC-ee interaction region. We analyse the excitation of trapped modes, which can accumulate electromagnetic energy and determine the locations of these modes. We study the unavoidable resistive-wall wake field, which is responsible for the direct beam pipe walls heating. We show the distribution of the heat load along the central part of the interaction region. We also present the cooling system design and results for temperature distribution in interaction region in the operational mode.
Paper: MOPA092
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPA092
About: Received: 10 May 2023 — Revised: 11 May 2023 — Accepted: 15 Jun 2023 — Issue date: 26 Sep 2023
MOPA115
Beam delivery of high-energy ion beams for irradiation experiments at the CERN Proton Synchrotron
315
Heavy-ion single event effect (SEE) test facilities are critical in the development of microelectronic components that will be exposed to the ionizing particles present in the hostile environment of space. CHARM High-energy Ions for Micro Electronics Reliability Assurance (CHIMERA) and HEARTS have developed a high-energy ion beam capable of scanning a wide range of Linear Energy Transfer (LET) at low intensities to study ionization effects on space-bound technology using CERN's Proton Synchrotron (PS). This contribution describes the extraction and transport of low-intensity lead ions at multiple energies to the CHARM facility at the East Area of CERN. Furthermore, it discusses the implementation of a Radio Frequency Knockout (RFKO) technique that streamlines beam extraction and enhances particle flux control and reproducibility across different energies, thereby improving performance and reliability in SEE testing.
Paper: MOPA115
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPA115
About: Received: 21 Apr 2023 — Revised: 15 May 2023 — Accepted: 20 Jun 2023 — Issue date: 26 Sep 2023
MOPA116
RF techniques for spill quality improvement in the SPS
319
The CERN Super Proton Synchrotron (SPS) aims at providing stable proton spills of several seconds to the North Area (NA) fixed target experiments via third-integer resonant slow extraction. However, low-frequency power converter ripple (primarily at 50 and 100 Hz) and high-frequency structures (mainly at harmonics of the revolution frequency) modulate the extracted intensity, which can compromise the performance of the data acquisition systems of the NA experiments. In this contribution, the implementation of Radio Frequency (RF) techniques for spill quality improvement is explored, with particular focus on empty bucket channelling. It is shown that both the main RF systems (at 200 and 800 MHz) can be successfully exploited to improve the SPS slow extraction.
Paper: MOPA116
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPA116
About: Received: 26 Apr 2023 — Revised: 10 May 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
MOPL002
AC excitation studies for full coupling operation
508
Betatron coupling resonance has been considered by many low emittance upgrade light sources as a candidate to produce round beams. Due to the limited literature on the topic, last year an experimental campaign was undertaken on the ALBA storage ring to establish limits and requirements to operate a light source in full coupling. The work highlighted how coupling can indeed produce a round beam with certain easiness but not free from shortcomings: the fractional betatron tunes must be set equal, resulting in a substantial constraint to the optics and requiring a sophisticated control of the optics itself in order to keep the resonance condition despite the movement of insertion devices and drifts. To work around these limitations, this year a different approach, based on the excitation of the coupling resonance with an A.C. skew quadrupole was tested. A first experiment was attempted by converting the existing tune excitation stripline into a skew quadrupole, but the limited available power allowed to produce only a barely perceptible coupling. The stripline was then turned into an electric deflector by removing the resistive terminations and allowing to drive the electrodes to higher voltage. Here the newly obtained results with the A.C excitation are presented.
Paper: MOPL002
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL002
About: Received: 02 May 2023 — Revised: 06 Jun 2023 — Accepted: 21 Jun 2023 — Issue date: 26 Sep 2023
MOPL003
Polarized proton operation at RHIC with partial snakes
512
A series of power outages during setup for RHIC Run 23 damaged two of the four helical dipole modules that comprised one of the full Siberian Snakes in RHIC’s Blue ring. The remaining two helical dipoles were reconfigured as a “partial” snake, one which rotates the spin by an angle less than 180 degrees. This partial snake configuration has a rotation angle and axis which both deviate from the ideal. We describe the compensatory measures taken to address the effects of these deviations. These include reconfiguring the other Blue snake to rematch the stable spin direction at injection and a change of the nominal store energy from 255 GeV to 254.2 GeV to improve the stable spin direction condition at store. Polarization transmission through RHIC acceleration was as good as with full snakes and we present some analytical and tracking results that corroborate the observed robustness with respect to deviations from ideal snakes.
Paper: MOPL003
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL003
About: Received: 02 May 2023 — Revised: 10 May 2023 — Accepted: 22 Jun 2023 — Issue date: 26 Sep 2023
MOPL011
Strategy for proton polarization in the Electron Ion Collider
523
The Electron Ion Collier (EIC) will utilize highly polarized electron and ion beams. To preserve polarization through numerous depolarizing resonances over the whole EIC hadron accelerator chain, harmonic orbit correction, partial snakes,horizontal tune jump system and full snakes have been used. A new scheme using skew quadrupoles to compensate horizontal intrinsic resonances is under development. In addition, close attentions have been paid to betatron tune control, orbit control and beam line alignment. The polarization of 60% at 255 GeV has been delivered to experiments with 1.8E11 bunch intensity. For the EIC era, the beam brightness has to be maintained to reach the desired luminosity.This will be achieved by electron cooling at injection of EIC hadron storage ring. Since we only have one hadron ring in the EIC era, existing spin rotator and snakes can be converted to six snake configuration for one hadron ring. The number of snakes can be increased. With properly arranged snakes in EIC and reduction of emittance, the polarization can reach 70% at 275 GeV. The general strategy of polarization preservation scheme in the injectors and hadron ring of the EIC is described in this paper.
Paper: MOPL011
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL011
About: Received: 02 May 2023 — Revised: 10 May 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
MOPL012
Non-destructive spin tune measurement of polarized protons in a storage ring
527
To maintain polarization in a polarized proton collider, it is important to know the spin tune of the polarized proton beam, which is defined as the number of full spin precessions per revolution. A nine-magnet spin flipper has demonstrated high spin-flip efficiency in the presence of two Siberian snakes. The spin flipper drives a spin resonance with a given frequency (or tune) and strength. When the drive tune is close to the spin tune, the proton spin direction is not vertical anymore, but precesses around the vertical direction. By measuring the precession frequency of the horizontal component, the spin tune can be precisely measured. A driven coherent spin motion and fast turn-by-turn polarization measurement are keys to the measurement. The vertical spin direction is restored after turning the spin flipper off. The fact that this manipulation preserves the polarization makes it possible to measure the spin tune during the operation of a polarized collider such as RHIC and EIC.
Paper: MOPL012
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL012
About: Received: 02 May 2023 — Revised: 09 May 2023 — Accepted: 11 May 2023 — Issue date: 26 Sep 2023
MOPL019
Mitigation of losses at injection protection devices in the CERN LHC
547
During loss maps performed with beam at injection energy in the LHC with the high octupole and chromaticity settings used for multi-train operation, large beam losses were observed at an injection protection device (TDIS). Although these losses did not present a threat to machine operation or protection, reducing them is of high importance to improve machine performance. Various strategies were developed to mitigate these losses, such as octupole setting optimization at constant Landau damping and vertical tune reduction. Further optimization of collimator settings is also considered. Results of experimental tests and first simulations are reported here together with considerations for the future.
Paper: MOPL019
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL019
About: Received: 03 May 2023 — Revised: 20 Jun 2023 — Accepted: 20 Jun 2023 — Issue date: 26 Sep 2023
MOPL024
Measurement and modelling of decapole errors in the LHC from beam-based studies
567
Studies of third-order chromaticity in the LHC during its initial two runs have consistently demonstrated a substantial discrepancy between the expected Q''' at injection and that observed in beam-based measurements. In 2022 during Run 3, for the first time, studies of Q''' have been complemented by measurements of chromatic detuning, being the momentum-dependence of amplitude detuning, and the decapole resonance driving term 𝑓1004. In this paper, these beam-based measurements are presented and compared to the magnetic model. Potential sources of the previously identified Q”’ discrepancy are discussed.
Paper: MOPL024
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL024
About: Received: 24 Apr 2023 — Revised: 08 May 2023 — Accepted: 11 May 2023 — Issue date: 26 Sep 2023
MOPL053
A booster free from spin resonances for future 100 km-scale circular e+e- colliders
662
Acceleration of polarized electron and positron beams to ultra-high beam energies is of interests for polarized beam applications in future 100km-scale e+e- circular colliders. However, it was widely envisaged that crossing hundreds of spin depolarization resonances would lead to severe depolarization during the energy ramp in the booster synchrotron. In this work, we have studied the spin resonance structure of a booster lattice for the Circular Electron Positron Collider (CEPC). The 100 km-scale booster lattice has a periodicity of 8 and each arc region contains hundreds of FODO cells. We show that the first super strong depolarization resonances only occur beyond 120 GeV, and other resonances are much weaker, due to the effectively very high periodicity of the lattice structure in terms of spin resonances. This finding is similar to the concept of ``Spin resonance free injector’’ for the Electron Ion Collider [V. Ranjbar, Phys. Rev. Accel. Beams, 20, 111003, 2018]. Spin tracking simulations verify that beam polarization can be mostly maintained in the fast ramping to 45.6 GeV and 80 GeV beam energies, without using special hardware like Siberian snakes. We also discuss possible measures to maintain beam polarization up to 120 GeV. This study opens the way for injection of highly polarized beams generated from the source into the collider rings, to enable resonant depolarization measurements as well as longitudinally polarized colliding beam experiments.
Paper: MOPL053
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL053
About: Received: 03 May 2023 — Revised: 12 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
MOPL055
Spin-polarization simulations for the Future Circular Collider e+e- using Bmad
670
The high precision measurement of the centre-of-mass energy in the Future Circular Collider e+e- (FCC-ee) at Z and W energies can be realized through resonant spin depolarization utilizing transversely polarized beams. This requires a guaranteed sufficiently-high spin polarization in the presence of lattice imperfections. Investigations of the impact of misalignments on the equilibrium polarization are conducted using analytical and Monte-Carlo spin simulations with Bmad. Potential optimization schemes to ensure high polarization using orbit bumps have been explored.
Paper: MOPL055
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL055
About: Received: 02 May 2023 — Revised: 06 May 2023 — Accepted: 11 May 2023 — Issue date: 26 Sep 2023
MOPL059
The status of the energy calibration, polarization and monochromatization of the FCC-ee
674
The Future Circular electron-positron Collider, FCC- ee, is designed for unprecedented precision for particle physics experiments from the Z-pole up to above the top-pair-threshold, corresponding to a beam energy range from 45.6 to 182.5 GeV. Performing collisions at various particle-physics resonances requires precise knowledge of the centre-of-mass energy (ECM) and collision boosts at all four interaction points. Measurement of the ECM by resonant depolarization of transversely polarized pilot bunches in combination with a 3D polarimeter, aims to achieve a systematic uncertainty of 4 and 100 keV for the Z-pole and W-pair-threshold energies respectively. The ECM itself depends on the RF-cavity locations, beamstrahlung, longitudinal impedance, the Earth’s tides, opposite sign dispersion and possible collision offsets. Application of monochromatization schemes are envisaged at certain beam energies to reduce the energy spread. The latest results of studies of the energy calibration, polarization and monochromatization are reported here.
Paper: MOPL059
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL059
About: Received: 02 May 2023 — Revised: 10 May 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
MOPL131
The Frascati DAFNE LINAC modulator upgrade
862
The Frascati linear accelerator was used as electron and positron source for the DAFNE collider and the Beam Test Facility (BTF) where the fixed target experiments as PADME or irradiation test for space components are ongoing. Builded in 1996 an upgrade of the L-C traditional resonant charging system is started in 2018 and today 3 of the 4 RF power stations modulator are upgraded from the 3-phase variable phase control (SCR) based on a full-wave bridge diode assembly to a new 2 constant-current capacitor charging power supplies. This paper will discuss the design of the upgrade and the performances of the systems in operation
Paper: MOPL131
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL131
About: Received: 03 May 2023 — Revised: 06 Jun 2023 — Accepted: 06 Jun 2023 — Issue date: 26 Sep 2023
MOPL150
Wakefield effects on dark current bunches for LESA
893
Alongside the new LCLS-II facility, a new electron beamline known as Linac to End Station A (LESA) is under construction at SLAC. LESA will use field-emitted dark current from the new superconducting accelerator to search for MeV- to GeV-scale dark matter. To predict the behavior of the dark current in LESA, we must account for the effects of wakefields. In the conventional analysis of long-range wakefields, the bunches are both the sources and subjects of collective effects. Since the contribution of dark current to the wakefield is negligible, the dark bunches are passive recipients of the wakefield kicks. However, we also lose some simplifying assumptions. In contrast to the main bunches, which are generated at a low subharmonic of the RF frequency, dark current is generated on every RF cycle of the source cavity. The dark current bunches may also occupy a much larger proportion of each RF bucket – possibly the entire longitudinal acceptance of the accelerator. These complications lead to effects that are not seen in the main bunches, such as “beating” of the betatron amplitudes along the dark bunch train. In this work, we present the theory behind this interaction and apply it to LESA.
Paper: MOPL150
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL150
About: Received: 04 May 2023 — Revised: 08 Jun 2023 — Accepted: 08 Jun 2023 — Issue date: 26 Sep 2023
MOPL176
Slow Extraction Techniques from Fixed Field Accelerators
945
Fixed Field Accelerators are a candidate for future hadron cancer therapy facilities as their high repetition rate and large energy acceptance enables novel treatment modalities such as high dose rate FLASH. However, conventional dose delivery mechanisms are still necessary, requiring continuous beam delivery over 1--30s. This work is the first study of slow extraction from a scaling Fixed Field Accelerator, using the LhARA facility for baseline parameters. At a horizontal tune of 10/3, the intrinsic sextupole strength of the nonlinear FFA magnetic field is sufficient to excite the resonance, although extraction is better controlled using an additional excitation sextupole at a tune close to 8/3, with radiofrequency knock-out extraction. Including considerations of issues due to nonlinear fields and limitations required to keep the tune energy-independent, slow extraction from Fixed Field Accelerators is successfully demonstrated.
Paper: MOPL176
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL176
About: Received: 31 Mar 2023 — Revised: 16 Jun 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
MOPL180
Proton and electron RLA optics design
958
We describe optics designs of the key components of proton and electron Recirculating Linear Accelerators (RLAs). They are presented in the context of a high-power hadron accelerator being considered at ORNL and a CEBAF electron energy doubling study, FFA@CEBAF, being developed at Jefferson Lab. Both concepts rely on the Fixed-Field Alternating gradient (FFA) arc optics designs where multiple beam passes are transported by a single beam line.
Paper: MOPL180
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL180
About: Received: 13 May 2023 — Revised: 16 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
MOPM014
Reducing floor vibration of TPS experimental hall caused by air handling units
1005
The Taiwan Photon Source (TPS) experimental facility has experienced vibration interference at approximately 16.8 Hz during experiments at the end station of the TPS 23A beamline, which was traced back to the air handling units (AHUs) located on the second floor of the outer ring area of TPS. The vibration of the AHUs not only affects the TPS beamline 23A end station but also all experimental areas. In this paper, we present two methods to reduce the floor vibration of the experimental hall caused by the AHUs. Firstly, we adjusted the operating frequency of each AHU fan to avoid resonance and reduce the vibration of the nearby experimental area floor, which can be reduced by up to 40%. Secondly, we installed additional air isolation mounts outside the AHU to further reduce the impact of the fans on floor vibrations, which resulted in a reduction of vibration transmission by about 30%. Our findings provide useful information for those dealing with vibration interference caused by AHUs and can help improve the experimental accuracy and efficiency in similar facilities.
Paper: MOPM014
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPM014
About: Received: 02 May 2023 — Revised: 08 May 2023 — Accepted: 12 May 2023 — Issue date: 26 Sep 2023
MOPM021
Feasibility of round beams in SLS 2.0
1027
Sharing of emittances between transverse planes has potential benefits in storage ring light sources. The larger vertical emittance significantly increases the Touschek lifetime, while the smaller horizontal emittance helps to mitigate the loss in brightness at high photon energies due to the larger vertical beam size and divergence. A fully coupled beam is considered as an optional operation mode for the SLS 2.0, should a longer beam lifetime be required. In this paper, we investigate the feasibility of having round beams in SLS 2.0 by operating on the linear difference resonance. We analyze the impact on the linear- and nonlinear performance of the machine, in particular the impact on Touschek lifetime when all apertures are included.
Paper: MOPM021
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPM021
About: Received: 02 May 2023 — Revised: 06 May 2023 — Accepted: 11 May 2023 — Issue date: 26 Sep 2023
MOPM022
TRIBs simulations for SLS 2.0
1031
The concept of Transverse Resonance Island Buckets (TRIBs) has recently gained attention in the storage ring light source community, and has found usage to, e.g., serve timing users and can enable fast polarity switching of the light in undulators. This contribution introduces two options for creating TRIBs in SLS 2.0 using either 3Qx or 4Qx resonances. Options for control of the islands using sextupoles and octupoles in SLS 2.0 are evaluated. The optics and equilibrium emittance within the islands are calculated and checked using tracking simulations. Furthermore, the diffusion of particles from the islands due to radiative effects and Touschek scattering is discussed.
Paper: MOPM022
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPM022
About: Received: 02 May 2023 — Revised: 06 May 2023 — Accepted: 11 May 2023 — Issue date: 26 Sep 2023
MOPM034
Shunt impedance calculations for an in-vacuum undulator at Petra IV
1064
A new in-vacuum undulator (IVU) with varying gap width is being developed for the new X-Ray source, PETRA IV at DESY. Its electromagnetic properties need to be investigated. These include, especially, the losses in the flexible taper transitions between the beam pipes and in the magnet array, as well as the impact of the IVU's impedance on beam stability. To assess the impedance of the structure, we employ numerical simulations. The challenges lie in the large size of the IVU, the wide frequency range due to the short bunch length, the highly resonant response of the system, and in the complex geometry of the structure. In a first step, wakefield simulations are carried out using CST Studio Suite. Subsequently, the shunt impedances are calculated by eigenmode simulations with the CST Studio Suite and a specialized in-house frequency domain impedance solver.
Paper: MOPM034
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPM034
About: Received: 03 May 2023 — Revised: 05 May 2023 — Accepted: 11 May 2023 — Issue date: 26 Sep 2023
MOPM039
On-resonance round beam experiment in the HLS-II storage ring
1079
The strong intra beam scattering effect and the increase in horizontal emittance become common issues for next-generation ultra-low emittance storage rings. The round beam can be an effective method to solve these problems. Moreover, the produced round synchrotron radiation is suitable for optical matching. The on-resonance tune is an easier method to achieve round beam. In this paper, simulation and experimental results are introduced based on the nominal lattice of the HLS-II storage ring.
Paper: MOPM039
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPM039
About: Received: 01 Apr 2023 — Revised: 06 May 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
MOPM052
Elettra 2.0 - the girder support design
1113
Elettra will be upgraded between 2025 and 2026 and the storage ring lattice will be totally different to enhance the emittance and improve the coherence of the machine. The storage ring design requires a stiff support system to reduce the impact of vibrations on the electron orbits, a high thermal stability as well as low static deformations. The magnets support system must be easy to transport, align and must be cost effective. In order to achieve these requirements, the magnets supports of each synchrotron cell are granite blocks long from 0.8 to 1.57 m and the girder alignment system consists of 3 main adjustment feet and 2 stiffeners. An optimization study was conducted de-fining the most effective location of the feet. Each magnet can be aligned on the girder by means of 3 levelling wedges that can be moved both manually and automatically by means of motorized actuators. A FEA calculation was carried out to optimize the design in order to achieve a target stiffness and an experimental test was performed on a prototype girder in order to verify the numerical results.
Paper: MOPM052
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPM052
About: Received: 10 May 2023 — Revised: 08 Jun 2023 — Accepted: 08 Jun 2023 — Issue date: 26 Sep 2023
MOPM071
Slow extraction with octupoles at CERN proton synchrotron to improve extraction efficiency
1144
The extraction inefficiency of the slow extraction process induces radioactivity in the area surrounding the electrostatic septum. Studies at the CERN Proton Synchrotron (PS) are investigating beam loss reduction techniques to improve the efficiency of the beams provided to the experiments of the East Area. Powering octupoles distorts the transverse phase-space of the extracted beam which can be exploited to maximize the number of particles in the field region of the septum with respect to the number lost on the septum. The effect of octupoles on the separatrices near the third-order resonance is simulated with MADX-PTC tools to observe phase space folding and to predict the multipole parameters needed to minimize beam loss. Experimental studies are performed to confirm the validity of the simulation models and to quantify the net benefit of using octupoles to improve the extraction efficiency.
Paper: MOPM071
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPM071
About: Received: 04 May 2023 — Revised: 07 May 2023 — Accepted: 15 Jun 2023 — Issue date: 26 Sep 2023
MOPM072
Dynamics of off-axis injection near the coupling resonance at PETRA IV
1148
The PETRA IV project will have a storage ring with an ultra-low natural emittance of 20 pm rad [1]. For an off-axis injection scheme with working points at the difference resonance it is important to assure the vertical excursion arising due to transversal coupling such, that injection efficiency is not compromised. In this contribution we present simulations results of an off-axis injection near the coupling resonance, which provides equal equilibrium emittances. Advantages and disadvantages of such a scheme are discussed.
Paper: MOPM072
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPM072
About: Received: 08 May 2023 — Revised: 09 May 2023 — Accepted: 12 May 2023 — Issue date: 26 Sep 2023
MOPM125
Study on a self-resonating optical cavity for high-brightness Laser-Compton Scattering X-ray sources
1257
Laser Compton Scattering (LCS) is a technique to produce quasi-monochromatic X-rays and gamma rays by colliding a laser with a high-energy electron beam produced by an accelerator. Although LCS light sources are expected to produce photons of the same quality in a small (6m x 8m) device as those from large synchrotron radiation facilities , the low number of scattered photons is an issue for practical use. To solve this problem, we have developed an optical cavity to generate colliding lasers with high repetition rate and high peak power. However, the operation of an optical cavity in an accelerator environment with high noise limits the stored optical power by maintaining resonance through resonator length control. Therefore, we have devised and are developing a self-resonating optical cavity in which the resonance is maintained spontaneously by connecting the optical storage resonator and the laser oscillator in a closed loop. In this talk, I will report on the current status of self-resonating optical cavity and its temperature dependence.
Paper: MOPM125
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPM125
About: Received: 24 Apr 2023 — Revised: 05 May 2023 — Accepted: 15 Jun 2023 — Issue date: 26 Sep 2023
TUXG1
J-PARC operation with the high repetition rate upgrade
1294
The main ring synchrotron (MR) of the Japan Proton Accelerator Research Complex (J-PARC) has provided high-intensity proton beams to the T2K long-baseline neutrino experiment, which requires high statistics to confirm the existence of CP violation. We plan to increase the beam power from 0.5 MW in 2021 operation to 1.3 MW by 2028 in the fast extraction mode of the MR. This upgrade supports higher statistics for T2K and the Hyper-Kamiokande long-baseline project, which will start from 2027. The scheme of the upgrade is to quicken the repetition period by a factor of two from 2.5 s in 2021 operation, and to increase the number of protons per pulse 30% more. This scheme requires hardware upgrades on the power supplies of the main magnets, high gradient RF system, collimator system, injection and fast extraction systems, and beam monitors. The upgrade of the MR is on schedule. The hardware upgrade for high-repetition operation was completed by 2022. The remaining upgrades will be accomplished in following several years to increase the number of protons per pulse. The improvement of the beam dynamics in the MR is also necessary to manage higher space charge effects due to increase of the beam intensity, and to localize beam losses at the collimator section in the MR more efficiently. This presentation reports the first results of the MR beam operation in the high repetition rate and the strategies to 1.3 MW operation based on beam study results.
Paper: TUXG1
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUXG1
About: Received: 03 May 2023 — Revised: 12 Jun 2023 — Accepted: 12 Jun 2023 — Issue date: 26 Sep 2023
TUOGB3
Spin transparency experiment test in RHIC
1343
A novel technique, called a spin transparency mode, for preservation and control of electron and ion spin polarization in colliders and storage rings has been proposed. The beam polarization can then be fully controlled by small adjustments of the snake axis orientations and snake strengths. An experiment has been carried out recently to test the concept. One of the RHIC rings is set to be “transparent” to the spin by making the axes of its two Siberian snakes nearly parallel. The polarization was rotated from vertical to radial and from up to down by varying the snake currents. This paper summarizes the recent experiment results and discusses the comparison with simulations.
Paper: TUOGB3
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUOGB3
About: Received: 02 May 2023 — Revised: 12 May 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
TUPA001
Copper surface treatment with deep UV ultrafast laser for improved photocathode photoemissive properties
1350
Surface nanostructuring is a promising approach when it comes to improving the quantum efficiency (QE) of materials for electron accelerator purposes at CERN. This is due to the plasmonic effect taking place in metallic materials at the nanoscale, when an electromagnetic wave interacts with a sub-wavelength feature. Ultrafast laser surface nanopatterning can be an efficient and times saving method for producing such nanostructures. We conducted a study of nanostructuring of copper surfaces with a deep-UV femtosecond laser. A wide range of fabrication parameters (speed, laser fluence and repetition rate) were tested. At different energy regimes we were able to produce Laser Induced Periodic Surface Structures (LIPSS), as well as spherical nanoparticles of tunable size and other types of periodic nanoscale features. Sub-wavelength periodic structures yield higher exaltation of surface plasmons under matching excitation wavelength, resulting in a potentially significant increase in QE of copper photocathodes. Moreover, by using the same laser source for nanomachining and photoemission, one can easily integrate the technology in and existing photoinjector.
Paper: TUPA001
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUPA001
About: Received: 13 May 2023 — Revised: 22 May 2023 — Accepted: 22 May 2023 — Issue date: 26 Sep 2023
TUPA002
Simulation of plasmonic effects in nanostructured copper surfaces for field-assisted photoemission
1354
We propose a simulation model of the field enhancement and quantum efficiency (QE) increase of metallic surfaces as a result of a surface nanostructuring. In the framework of photoinjector facilities for electron accelerators at CERN, achieving optimal nanostructuring parameters may become a significant asset. The presence of a well-designed periodic surface topography can give rise to plasmonic resonance and coupling effects within the structures, which yields a local increase in electron density and an electric field enhancement. This model is used to provide a deeper insight into these effects. We investigate the dependency of the electron emission enhancement on the nanopattern geometry and incident wavelength on the plasmonic resonance. We examine, based on former experimental results, the performance of Laser Induced Periodic Surface Structures (LIPSS) and other types of periodic nanoscale features, but we also demonstrate the surprisingly strong contribution of nanoparticles in the global field enhancement of the surface. These particles are a common side effect of ultrafast laser surface processing and themselves exhibit unique plasmonic resonance properties.
Paper: TUPA002
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUPA002
About: Received: 04 May 2023 — Revised: 07 May 2023 — Accepted: 15 Jun 2023 — Issue date: 26 Sep 2023
TUPA115
Development of a spin filter polarimeter for polarization measurement of pulsed H+/D+ ion beam at IMP
1577
Spin is one of the intrinsic properties of particles. However, there are many incomprehensible problems about it. High energy polarized electron-ion collisions will provide unprecedented conditions for the study of spin physics and lead us to the study on the inner structure of matter and fundamental laws of interactions, and other forefronts of natural science. As the Phase II of the HIAF (High Intensity heavy ion Accelerator Facility) project, Electron-Ion Collider in China (EicC)* is under conceptual design phase. The production, acceleration and collision of polarized ions and electrons are essential for EicC accelerator facility. Therefore, R&D work such as key technologies prototyping has already been initiated. A spin polarized ion source for the production of intense proton and deuterium ion beams with high polarization is under development at the Institute of Modern Physics (IMP). Polarization is one of the key characteristics for polarized ion beams. To make the polarization measurement more precise, faster and more convenient, a polarimeter based on nuclear spin filter (SFP for short) is under design, which measures the polarization directly behind the ion source. Scheme of the SFP will be presented, the measurement process, simulations for crucial physical questions and design of theSFP will be discussed.
Paper: TUPA115
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUPA115
About: Received: 28 Apr 2023 — Revised: 06 May 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
TUPA120
Fabrication progress of the prototype spoke cavity for the JAEA-ADS linac
1588
The Japan Atomic Energy Agency (JAEA) has been proposing an accelerator-driven system (ADS) as a future nuclear system to efficiently reduce high-level radioactive waste generated in nuclear power plants. As a first step toward the full-scale design of the CW proton linac for the JAEA-ADS, we are now prototyping a low-beta (around 0.2) single-spoke cavity. The actual cavity fabrication started in 2020. Most of the cavity parts were shaped in fiscal year 2020 by press-forming and machining. In 2021, we started welding the shaped cavity parts together. By preliminarily investigating the optimum welding conditions using mock-up test pieces, each cavity part was joined with a smooth welding bead. So far, we have fabricated the body section and the beam port section of the cavity. By measuring the resonant frequency of the temporarily assembled cavity, we have confirmed that there is no significant problem with the cavity fabrication. In this paper, fabrication progress of the prototype spoke cavity is presented.
Paper: TUPA120
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUPA120
About: Received: 02 May 2023 — Revised: 10 May 2023 — Accepted: 15 Jun 2023 — Issue date: 26 Sep 2023
TUPM002
Commissioning status of the RAON superconducting accelerator
2192
The Rare isotope Accelerator Complex for ON-line experiments (RAON) has been proposed as a multi-purpose accelerator facility for providing beams of exotic rare isotopes of various energies. It can deliver ions from hydrogen (proton) to uranium. Protons and uranium ions are accelerated up to 600 MeV and 200 MeV/u respectively. It can provide various rare isotope beams which are produced by isotope separator on-line system. The RAON injector was successfully commissioned in 2022 to study the beam parameters from the main technical systems, such as the ECR ion source and RFQ, and to find the optimized LEBT and MEBT setpoints and matching conditions. In addition, the low-energy superconducting linac (SCL3) is under commissioning. In this paper, we present the current beam commissioning status of the RAON injector and superconducting accelerator.
Paper: TUPM002
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUPM002
About: Received: 03 May 2023 — Revised: 11 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
TUPM017
Design of a QWR cavity for the new ISIS MEBT
2227
The quarter wave resonator (QWR, a.k.a. λ/4 resonator) for the new ISIS MEBT is a bunching cavity that longitudinally compresses the H- beam into smaller bunches. It has 2 gaps with a distance of βλ/2 between mid-gaps, and works in π mode at the resonant frequency of 202.5 MHz, with a phase angle of -90 degrees. The maximum voltage per gap (E0L) is set to 55 kV. A detailed RF model has been developed to tune the main dimensions to the required frequency and to estimate the Kilpatrick ratio and the RF power dissipation. The cavity is designed to be made of copper plated stainless steel, which has a considerable effect on the design of the cooling system; the thermal calculations include a thermo-mechanical analysis to estimate the dynamic tuning requirements. The cavity has two tuners to allow for a fine and a coarse tuning of the resonant frequency. The manual tuner coarsely adjusts the frequency to cope with the manufacturing tolerances. The automatic tuner finely tunes the frequency within a range of working temperatures. The tuners are heavily coupled both in terms of frequency resolution and tuning range, which presents some challenges to the design. The design of the power coupler was adapted to the QWR from another project and the coupling coefficient was adjusted to the new cavity. A sensitivity analysis for the critical dimensions was also developed, but is not presented here.
Paper: TUPM017
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUPM017
About: Received: 10 Mar 2023 — Revised: 05 May 2023 — Accepted: 15 Jun 2023 — Issue date: 26 Sep 2023
TUPM031
Non-scaling fixed-field proton accelerator with constant tunes
2257
Recent studies by Dejan Trbojevic have confirmed that Non-Scaling Fixed Field Accelerators (NS-FFAs) can have their tune dependence on momentum flattened by adding non-linear components to the magnet fields, although not necessarily for an unlimited momentum range. This paper presents such a cell suitable for the proposed 3-12MeV FETS-FFA proton R&D ring at RAL. The nonlinear magnetic field components are found automatically using an optimiser and settings covering a ring tune range of one unit in both planes independently are attainable. A fully configurable magnet with multiple windings across its horizontal aperture has been designed in 2D using Poisson, which can produce the required nonlinear fields without exceeding 5A/mm^2 current density.
Paper: TUPM031
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUPM031
About: Received: 20 Apr 2023 — Revised: 05 May 2023 — Accepted: 11 May 2023 — Issue date: 26 Sep 2023
TUPM034
Dynamic aperture studies for vertical fixed field accelerators
2269
Vertical orbit excursion Fixed Field Accelerators (vFFAs) feature highly non-linear magnetic fields and strong transverse motion coupling. The detailed study of their Dynamic Aperture (DA) requires computation codes allowing long-term tracking and advanced analysis tools to take the transverse motion linear and non-linear coupling into account. This coupling completely transforms the beam dynamics compared to a linear uncoupled motion, and an explicit definition of the DA is needed to characterize the performance and limitations of these lattices. A complete study of the DA in the 4D phase space in highly non-linear and strongly coupled machines must give a measure of the stability domain but also means to assess the operating performance in the physical coupled space. This work presents a complete set of methods to perform such detailed analysis. These methods were explored and compared to compute and characterize the DA of an example vFFA lattice. The whole procedure can be further applied to evaluate DA using realistic models of the magnetic fields, including fringe fields and errors.
Paper: TUPM034
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUPM034
About: Received: 10 May 2023 — Revised: 13 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
TUPM038
RF kicker at the Cyrcé facility in Strasbourg
2281
The Cyrcé facility of IPHC in Strasbourg operates a TR24 cyclotron to produce medical isotopes, lead radiobiology programs and test detectors. A RF kicker has been developed in order to discard one beam bunch over two to get a rate close to 40MHz. An RF voltage at a quarter of the cyclotron frequency applied to a deflector in the injection line allows to reach that goal. The 30keV DC beam from the ion source is discarded except at the zero crossing of the RF. With a proper phase difference between the two RF, only one accelerating phase of the cyclotron over two is populated resulting in a bunch rate of 42.5MHz. A second need for radiobiology is to switch the beam on and off with the highest raise and fall times. This is done by adjusting the phase of the kicker to block the beam. The kicker is made of a collimator (diam. 8 mm), followed by 2 deflectors ( 55 mm long, 50 mm wide) spaced by 40 mm and a second collimators (diam. 6mm) at 160 mm downstream the deflectors, also used as a beam dump for the deflected ions. The high voltage is achieved by a resonant circuit consisting of a coil and the deflector, excited by a second coil. A second variable capacitor is added for tuning. The excitation coil position allows to adjust the matching. Scintillators associated with fast electronics has shown that the bunche rate was half the cyclotron frequency as expected. The beam rejection was measured to values up to 10-5. The raising and falling times of the beam was measured to 10µs.
Paper: TUPM038
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUPM038
About: Received: 02 May 2023 — Revised: 22 May 2023 — Accepted: 22 Jun 2023 — Issue date: 26 Sep 2023
TUPM046
Study for space charge effect in tune space at CSNS-II/RCS
2299
CSNSII is an upgrade project of China Spallation Neutron Source (CSNS), which needs to increase the beam power from 100kW to 500kW. In order to find a suitable working point area in advance and evaluate the influence of space charge effect on CSNSII, the measurements of beam loss with different tunes on CSNS was carried out and beam loss simulation in transverse tune space on CSNSII has been performed using PyORBIT code. We gave the relationship between the beam survival rate and the working point, compared four groups of candidate working points and confirmed the influence of the fourth-order resonance on the beam through the single particle model.
Paper: TUPM046
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUPM046
About: Received: 03 May 2023 — Revised: 08 May 2023 — Accepted: 12 May 2023 — Issue date: 26 Sep 2023
TUPM055
Numerical simulation study towards 1.3-MW beam operation at J-PARC MR
2316
In the J-PARC Main Ring, a project to upgrade the beam power to 1.3 MW is currently underway. The most important issues in realizing such a high-power beam operation are controlling and minimizing beam loss, which are essential for sustainable beam operation allowing hands-on maintenance. In this paper, we report on our recent efforts to understand the mechanism of beam loss and to reduce it.
Paper: TUPM055
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUPM055
About: Received: 29 Apr 2023 — Revised: 07 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
TUPM077
Studies of the spin coherence time of protons at COSY
2379
The search for the Electric Dipole Moments (EDM) of charged particles in storage rings necessitates polarized beams with long Spin Coherence Time (SCT) of the circulating beam. The SCT is the time during which the RMS spread of the orientation of spins of all particles in the bunch reaches one radian. A long SCT is needed to observe the coherent effect of a polarization build-up induced by the EDM. For deuterons a SCT of 1000 s has been achieved at the COoler SYnchrotron COSY (Jülich, Germany). Accomplishing such long SCT for protons is far more challenging due to their higher anomalous magnetic moment, but essential for the planned EDM experiments. It has been shown that for protons, the SCT is strongly influenced by nearby intrinsic and integer spin resonances. The strengths of the latter have been calculated for a typical optics setting of COSY and the overall influence on the SCT was predicted. In addition, the efficiency of proton spin flipping with an RF-solenoid from initially vertical direction into the ring plane is also investigated.
Paper: TUPM077
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUPM077
About: Received: 19 Apr 2023 — Revised: 09 May 2023 — Accepted: 15 Jun 2023 — Issue date: 26 Sep 2023
TUPM091
Investigating alternative extraction methods at MedAustron
2419
MedAustron is an ion therapy facility for protons and carbon ions located in Wiener Neustadt, Austria. The beam is presently extracted for clinical operation from the synchrotron with third-order resonant slow extraction via acceleration with a betatron core. However, due to the flexibility of the synchrotron operation for Non Clinical Research (NCR) purposes, other extraction methods can be investigated for potential improvement of the machine performance as presented in this work. Radio-Frequency Knock Out (RFKO) extraction was investigated by applying an RF signal voltage across the horizontal Schottky plates in the synchrotron. Different excitation signals were evaluated with the required transverse excitation frequency band applied. Investigation of the synchronous ramping of all synchrotron magnets for extraction via Constant Optics Slow Extraction operation (COSE) was undertaken for a bunched beam in order to extend the implementation of COSE with possible Multi Energy Extraction (MEE). The last extraction method presented here is via longitudinal RF manipulation in order to extract the beam by sweeping a properly configured empty bucket through the beam stack. This method is known as Phase Displacement Extraction (PDE). Extraction rates with these methods were observed which meet the clinical requirements and might also be considered compatible with FLASH.
Paper: TUPM091
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUPM091
About: Received: 03 May 2023 — Revised: 22 May 2023 — Accepted: 22 May 2023 — Issue date: 26 Sep 2023
TUPM097
Study on spill quality and transit times for slow extraction from SIS18
2435
Slowly extracted beams from a synchrotron have temporal fluctuations, the so-called spill micro structure. The reason is related to power supply ripples that act on the quadrupole magnets, leading to unintended tune fluctuations during extraction. Related simulations regarding the dependency of spill quality on the power supply ripples are executed with varying excitation levels of the sinusoidal ripples and bandwidth-limited white noise. In addition, transit time spread is simulated, a few simulation approaches are proposed, and related data analysis procedures and preliminary results are described.
Paper: TUPM097
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUPM097
About: Received: 03 May 2023 — Revised: 12 May 2023 — Accepted: 22 Jun 2023 — Issue date: 26 Sep 2023
TUPM099
Status of SIS100 slow extraction design including effects of measured magnetic field errors
2443
The synchrotron SIS100 at FAIR, currently under construction in Darmstadt, Germany, will deliver slow extracted proton and ion beams up to 100 Tm employing resonant extraction. Its compact super-ferric dipole and quadrupole magnets allow fast ramping of magnetic field up to 4 T/s and 57 (T/m)/s, respectively. Recently, field errors has been measured for the dipole magnets and the first batch of quadrupole magnets. Higher order multipoles may interfere with resonant extraction, changing the geometry of the separatrix and conditions for resonant particles. The latter are affected most during their last turns and in the extraction channel owing to their large amplitudes, which amplify the effect of higher order multipoles. SIS100 comprises a set of corrector magnets up to octupole order, which can be used to compensate the impact of magnetic field errors. In this contribution, we report on the status of the slow extraction simulation studies including field errors. Furthermore, we present alternative working points for slow extraction, which are necessary to avoid the transition energy for some of beams required by the FAIR experiments.
Paper: TUPM099
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUPM099
About: Received: 29 Apr 2023 — Revised: 05 Jun 2023 — Accepted: 22 Jun 2023 — Issue date: 26 Sep 2023
TUPM116
Benchmarking simulations of slow extraction driven by RF transverse excitation at the CERN Proton Synchrotron
2487
Resonant slow extraction is a beam extraction method which provides a continuous spill over a longer duration than can be achieved with fast single-turn or non-resonant multi-turn extraction. By using transverse excitation to drive the circulating particles onto the resonance, a beam can be delivered to stationary target experiments which require low intensity, long-duration beams. In order to accurately and efficiently simulate the extraction process over a wide range of timescales, new modelling tools and computing platforms must be explored. By utilising optimised computational hardware - such as General Purpose Graphics Processing Units (GPGPUs), and next-generation simulation software (such as Xsuite), computation times for simulations can be reduced by several orders of magnitude. This contribution presents recent developments of resonant slow extraction modelling and benchmarking with a comparison to measurements made at CERN’s Proton Synchrotron (PS), with a particular focus on understanding the dynamics of transverse RF excitation and effect on spill quality.
Paper: TUPM116
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUPM116
About: Received: 02 May 2023 — Revised: 10 May 2023 — Accepted: 20 Jun 2023 — Issue date: 26 Sep 2023
TUPM137
Differential equation model of tune ripple effect on beam spill ripple in RFKO slow extraction
2557
Beam uniformity is an important factor that must be considered in slow extraction optimization, and the tune ripple caused by the power supply ripple is an important factor that causes beam uniformity to deteriorate. In this study, based on the beam excitation concept for two regions (extraction and diffusion regions), a differential equation of beam spill under the influence of a mono frequency tune ripple was established. By solving and analysing the differential equation, several conclusions were obtained and verified by simulation.
Paper: TUPM137
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUPM137
About: Received: 28 Apr 2023 — Revised: 23 Jun 2023 — Accepted: 23 Jun 2023 — Issue date: 26 Sep 2023
TUPM138
Optimization of low-energy slow extraction efficiency of XiPAF
2561
Xi'an Proton Application Facility (XiPAF) synchrotron provides 10~200MeV proton beam for the experimental simulation of the space radiation environment. Due to the space charge effect, the slow extraction of 10 MeV proton beam is a work full of challenges. In a past experiment, the total extraction efficiency was over 65% with 4.5 ~ 6.5×1010 protons stored before extraction but decreased to 52% with 9×1010 protons stored. In order to study the beam loss caused by a strong space charge effect, based on experimental parameters, the beam loss fractions at different positions of XiPAF synchrotron are obtained through the simulation. According to the beam loss analysis, optimized parameters are found for reference in subsequent experiments. It is also noted that negative beam average momentum spread before extraction is beneficial to the improvement of extraction efficiency
Paper: TUPM138
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUPM138
About: Received: 28 Apr 2023 — Revised: 11 May 2023 — Accepted: 11 May 2023 — Issue date: 26 Sep 2023
TUPM139
Simulation and experiment of low-energy slow extraction at XiPAF
2565
Extraction by third order resonance in low-energy stage will suffer from strong space charge effect, high beam emittance, high power ripple and so on. Low-energy slow extraction at 10 MeV has been explored theoretically and experimentally at synchrotron of Xi'an Proton Application Facility (XiPAF), which is a compact synchrotron with injection energy of 7 MeV and extraction energy up to 230 MeV. In this paper, simulation and experiment results of slow extraction of 10 MeV intense beam are presented. By using high-order harmonic excitation, the RF-KO slow extraction scheme below resonance is the best choice for slow extraction in low-energy stage with strong space charge effect. Slow extraction experiment is carried out when the maximum incoherent tune shift of space charge reaches -0.06, during which, quasi-uniform extracted beam and extraction rate around 65% are achieved.
Paper: TUPM139
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUPM139
About: Received: 03 May 2023 — Revised: 30 Jun 2023 — Accepted: 30 Jun 2023 — Issue date: 26 Sep 2023
WEPA023
Impact of the neutral molecule trapping on beam lifetime and beam profile
2697
This proceeding addresses the effect of the neutral molecules trapped by the beam. It is in particular discussed the effect of a non-uniform neutral molecule distribution on the beam profile and the resulting beam lifetime. According to the trapping temperature it is discussed in a general framework how the beam profile is modified. and the consequent beam loss.
Paper: WEPA023
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPA023
About: Received: 01 Apr 2023 — Revised: 26 Jun 2023 — Accepted: 26 Jun 2023 — Issue date: 26 Sep 2023
WEPA025
Space-charge limit in hadron synchrotrons induced by a gradient error
2705
The half-integer resonance is considered to be one of the strongest effects limiting the intensity of the FAIR SIS100 heavy-ion synchrotron which is currently under construction at GSI. Results of simulations under realistic synchrotron-operation conditions show that for bunched beams, a relatively small gradient error can result in a large half-integer stop-band width significantly reducing the maximum achievable bunch intensity. In addition to the results of simulations in SIS100, we characterize the half-integer stop band in SIS18 using experimental data.
Paper: WEPA025
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPA025
About: Received: 03 May 2023 — Revised: 17 May 2023 — Accepted: 22 Jun 2023 — Issue date: 26 Sep 2023
WEPA064
Generalized gradient map tracking in the Siberian snakes of the AGS and RHIC
2793
Accurate and efficient particle tracking through Siberian Snakes is crucial to building comprehensive accelerator simulation model. At the Alternating Gradient Synchrotron (AGS) and Relativistic Heavy Ion Collider (RHIC), Siberian Snakes are traditionally modeled in MAD-X by Taylor map matrices generated at specific current and energy configurations. This method falls short during ramping due to the nonphysical jumps between matrices. Another common method is to use grid field maps for the Snakes, but field map files are usually very large and thus cumbersome to use. In this work, we apply a new method called the Generalized Gradient (GG) map formalism to model complex fields in Siberian Snakes. GG formalism provides an analytic function in x and y for which automatic differentiation, i.e. Differential Algebra or Truncated Power Series Algebra can find accurate high order maps. We present simulation results of the Siberian Snakes in both the AGS and RHIC using the Bmad toolkit for accelerator simulation, demonstrating that GG formalism provides accurate particle tracking results.
Paper: WEPA064
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPA064
About: Received: 03 May 2023 — Revised: 06 May 2023 — Accepted: 15 Jun 2023 — Issue date: 26 Sep 2023
WEPA070
Calculation of beam sizes in coupled electron storage rings
2813
The description of coupling phenomena in electron storage rings is extended beyond the very common formula based on the coupled Hamiltonian [1] into the region where the small coupling is in competition with damping and diffusion from synchrotron radiation. In the derivation, the moment mapping approach is used in combination with the simplified simulation of radiation effects introduced by Hirata and Ruggiero [2]. The results of this theoretical approach are compared to the predictions of well-established theories dealing with coupling in electron storage rings: The envelope mapping approach from Ohmi, et al. [3], and Chao’s SLIM approach [4]. [1] G. Guignard, “Betatron coupling and related impact of radiation”, Phys. Rev. E 51, 6104, June 1995, or his contributions to CERN Accelerator Schools [2] K. Hirata, F. Ruggiero in “Treatment of Radiation for Multiparticle Tracking in Electron Storage Rings”, Part. Acc. Vol. 28, pp. 137-142 (1990) [3] K. Ohmi, et al., in “From the Beam-Envelope Matrix to Synchrotron-Radiation Integrals”, Phys. Rev. E, Vol. 49, p. 751 [4] A. Chao, in ”Evaluation of Beam Distribution Parameters in an Electron Storage Ring”, J. Appl. Phys. 50, 595 (1979) or SLAC-PUB-2143, June 1978
Paper: WEPA070
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPA070
About: Received: 02 May 2023 — Revised: 10 May 2023 — Accepted: 21 Jun 2023 — Issue date: 26 Sep 2023
WEPA071
Bloch equation for the description of linear coupling in storage rings
2817
Linear coupling in storage rings mixes horizontal and vertical beam motion. This is similar to the mixing of states in an atomic two-level system by a resonant laser interaction or the mixing of the two states of any spin-½ particle in static and dynamic external magnetic fields like, for example, in nuclear magnetic resonance, NMR, measurements. These coupled two-level systems are usually described by the Bloch equation [1] which is a set of coupled, first-order differential equations connecting the population of the states with some other parameters which contain in addition to the strength of the coupling and the detuning, some sort of phase information of the involved states. In linearly coupled storage rings horizontal and vertical emittance can be viewed as the population of ground and excited level and it will be shown that the Bloch equations can also model the time-dependent evolution of the transverse emittances of an ensemble of circulating particles. This is especially useful in cases where the emittance is exchanged by crossing the coupling resonance or where the coupling strength itself is a function of time. [1] F. Bloch, “Nuclear induction,” Physical Review, vol. 70, no. 7-8, pp. 460–474, 1946.
Paper: WEPA071
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPA071
About: Received: 02 May 2023 — Revised: 10 May 2023 — Accepted: 21 Jun 2023 — Issue date: 26 Sep 2023
WEPA115
RF design of the pulse compression system for the klystron-based CLIC main linac
2924
A pulse compression system based on double-height waveguides was designed for the Klystron-based CLIC main linac. The optimized power gain of the system is 3.81 with the particular pulse shape required for the CLIC-K accelerating structure. This pulse compression system consists of a main Barrel Open Cavity (BOC)-type pulse compressor and 4 novel correction cavities. The BOC pulse compressor has the Q0 of 2.36e5 with working mode TM1,1,32 and the β of 6.6. A novel coupling waveguide network which can ease the machining procedure was designed for the BOC pulse compressor. For the correction cavities, a new method based on a single cylinder cavity and a 3-dB hybrid was studied. Each of the correction cavities has the Q0 of 5e4 and the β of about 1.3.
Paper: WEPA115
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPA115
About: Received: 28 Apr 2023 — Revised: 11 May 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
WEPA130
Bimodal design of 500 MHz and 1.5 GHz normal conducting RF cavity for advanced synchrotron radiation facilities
2966
The advanced storage ring light source needs to realize ultra-low emissivity beam operation, and improving the Touschek lifetime puts forward higher requirements for the performance of RF cavity. In this paper, a novel bimodal normal conducting RF cavity is proposed. In one cavity, two power sources will be connected at the same time to realize the simultaneous operation of the two frequencies. The TM010 mode with the frequency of 500MHz is used for acceleration, and the TM020 mode with the frequency of 1.5GHz is used as the third harmonic to improve the height of the RF bucket and achieve the purpose of lengthening the beam bunch. Two couplers are designed to adapt to the working characteristics of bimodal RF cavity.
Paper: WEPA130
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPA130
About: Received: 21 Mar 2023 — Revised: 06 Jun 2023 — Accepted: 06 Jun 2023 — Issue date: 26 Sep 2023
WEPA133
Test stand for conditioning high power tetrodes at TRIUMF
2973
A major part of the 520 MeV Cyclotron's RF system is the high-power RF amplifier. The amplifier is based on eight 4CW250,000B tetrodes. A new high-power tetrode or a high-power tetrode that underwent refurbishing could trip the RF system through inner sparks. The likelihood of those sparks should be reduced prior to applying nominal power to the new and refurbished tetrodes. This could be achieved by RF conditioning of these tetrodes on a test stand. The test stand represents a 150 kW RF amplifier loaded by a dummy load. The amplifier is built using common grid schematics. The test stand's output stage incorporates the 4CW250,000B tetrode that is under test. This paper describes the mechanical and electrical designs of the test stand, procedures of testing and conditioning for 4CW250,000B tetrodes, and the results of test stand's commissioning.
Paper: WEPA133
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPA133
About: Received: 01 Apr 2023 — Revised: 11 May 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
WEPA176
Investigation of the fabrication method for the 3rd harmonic superconducting double-cell cavity
3053
The 3rd harmonic cavity is a key component for the 4th generation storage ring. A bunch lengthening by the harmonic cavity increases the Touschek lifetime, which can reduce the emittance in the storage ring. The resonant frequency is selected as 1500 MHz due to the resonant frequency of the main RF cavities being 500 MHz. The prototype cavity is an elliptical double-cell geometry to reduce power losses. Based on this design, three niobium cavities are fabricated. Deep drowned half-cells are welded by the electron beam welding machine after trimming at the edge of the equator and iris. The surface treatments are performed to increase the quality factor such as buffered chemical polishing, high-pressure rinsing, and annealing. In this paper, we presented the fabrication method of the 3rd harmonic superconducting cavity from niobium sheets to an elliptical double-cell cavity.
Paper: WEPA176
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPA176
About: Received: 02 May 2023 — Revised: 09 May 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
WEPA182
Multi-physics simulation of quadrupole resonators in the time domain under uncertainties
3063
Exploring the fundamental properties of materials, including niobium or Nb3Sn, in high-precision surface resistance measurements is relevant to superconducting radio-frequency (RF) technology. For the precise determination of the RF properties of such materials, the calorimetric measurement is carried out with a quadrupole resonator (QPR). Mathematically, a QPR model is governed by a set of electromagnetic-stress-heat (EM-S-T) equations in the time domain under geometric and material uncertainties. It allows for profound insight into the QPR physics phenomena, such as dynamic Lorentz force detuning and microphonics, potentially resulting in measurement bias observed for the third operating mode of the given HZB-QPR (1.3 GHz). On top of the coupled EM-S-T problem, due to manufacturing imperfections, the stochasticity of input parameters substantially affects the performance of QPRs. Thus, uncertainty quantification (UQ) becomes necessary to provide reliable and predictable simulations of QPRs. The generalized polynomial chaos (gPC) expansion technique with the stochastic collocation method is proposed to find the UQ propagation by the QPR model. This methodology offers a more realistic mathematical model of the QPR, providing statistical moments, local and variance-based sensitivity, and cumulative/probabilistic density functions. Based on that information, a physically-based approach can be proposed to re-design the QPR and improve the measurement accuracy.
Paper: WEPA182
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPA182
About: Received: 04 May 2023 — Revised: 06 Jun 2023 — Accepted: 06 Jun 2023 — Issue date: 26 Sep 2023
WEPL007
Measurement and simulations of the energy variation-induced orbit motion in a low momentum compaction APS lattice
3116
The APS Upgrade storage ring will keep the same rf system that is currently used at APS. This rf system has amplitude and phase noise dominated by the lines at 60, 180, and 360 Hz. APS presently operates with a synchrotron frequency close to 2 kHz, which is far away from the rf noise frequencies, but APS-U will operate with a bunch-lengthening cavity, which could lower the synchrotron frequency down to the range between 100 to 500 Hz depending on the cavity setup. Such low synchrotron frequency could lead to resonant amplification of the energy variation-induced orbit motion. In this paper, we describe measurements of the orbit motion at APS in a specifically designed low momentum compaction lattice that allowed us to lower synchrotron frequency below 300 Hz. We also show good agreement with our simulations.
Paper: WEPL007
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL007
About: Received: 03 May 2023 — Revised: 09 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
WEPL014
Higher-order spin depolarization analysis
3133
Current and historic tracking studies of the RHIC accelerator lattice find difficulty in explaining the transmission efficiency of spin polarization from the AGS extraction to RHIC storage energies. In this paper, we discuss mechanisms that result in resonant depolarizing behavior, beyond the usual intrinsic and imperfection resonance structures. In particular, the focus of this paper will be on higher-order resonances that become apparent in the presence of snakes. The set of conditions that identify higher-order spin-orbit resonances are 𝜈 = 𝑗0 + 𝑗 ⃗ ⋅𝑄⃗for integers (𝑗0, 𝑗) ∈ ℤ^4, where 𝜈 is the spin tune and 𝑄⃗ contains the orbit tunes. Note that we do not use the closed-orbit spin tune 𝜈0 but rather the amplitude-dependent spin tune 𝜈(𝐽𝑥, 𝐽𝑦, 𝐽𝑧) that depends on the phase-space amplitudes. While Sibrian snakes keep 𝜈0 at 1/2, the amplitude-dependent spin tune can deviate from 1/2 and can cross resonances during acceleration.
Paper: WEPL014
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL014
About: Received: 03 May 2023 — Revised: 14 May 2023 — Accepted: 22 Jun 2023 — Issue date: 26 Sep 2023
WEPL024
Impact of two-dimensional decoherence on the measurement of resonance driving terms
3162
In the presence of a tune spread induced by chromaticity or amplitude detuning, decoherence will lead to the damping of the beam centroid motion after a single transverse excitation. This in turn has implications for the analysis of turn-by-turn based optics measurements, as it affects the precision of the spectral analysis. In the past, it has been shown how the effect of decoherence on spectral lines in a single plane can be accounted for. In this paper, this work will be extended to include the effect from both transverse planes. The derivations are then applied on data taken at the IOTA ring at FNAL to study resonance driving terms.
Paper: WEPL024
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL024
About: Received: 03 May 2023 — Revised: 10 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
WEPL045
Employing octupole magnets for nonlinear optimization of Iranian Light Source Facility storage ring
3219
Limited dynamic aperture which is in the consequence of strong nonlinearities in a low emittance storage ring, is a challenging issue from beam dynamics point of view. In the present study, we have applied three families of focusing and defocusing octupoles to the storage ring lattice with the aim of increasing dynamic aperture and beam lifetime . We have discussed different methods to optimize of the position and strength of octupoles so that each octupole family fights a specific resonance driving term.
Paper: WEPL045
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL045
About: Received: 03 May 2023 — Revised: 09 May 2023 — Accepted: 15 Jun 2023 — Issue date: 26 Sep 2023
WEPL052
Improved measurements of nonlinear integrable optics at IOTA
3230
Nonlinear integrable optics (NIO) are a promising novel approach at improving the stability of high intensity beams. Implementations of NIO based on specialized magnetic elements are being tested at the Integrable Optics Test Accelerator (IOTA) at Fermilab. One method of verifying proper implementation of these solutions is by measuring the analytic invariants predicted by theory. The initial measurements of nonlinear invariants were performed during IOTA run in 2019/20, however the covid-19 pandemic prevented the full-scale experimental program from being completed. Several important improvements were implemented in IOTA for the 2022/23 run, including the operation at higher beam energy of 150 MeV, improved optics control, and chromaticity correction. This report presents on the improved calibrations of the NIO for nonlinear invariant measurements.
Paper: WEPL052
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL052
About: Received: 03 May 2023 — Revised: 10 May 2023 — Accepted: 20 Jun 2023 — Issue date: 26 Sep 2023
WEPL078
Analyzing and optimizing dynamic aperture based on minimizing the fluctuation of resonance driving terms
3288
Minimizing resonance driving terms (RDTs) is a traditional approach to enlarge the dynamic aperture (DA) of a storage ring. However, small RDTs can not guarantee a large DA. In this paper, the fluctuation of RDTs along the ring is taken into consideration. A large number of nonlinear lattice solutions based on one double-bend achromat lattice are analyzed. The results show that minimizing the RDT fluctuations can more effectively enlarge the DA area than minimizing the commonly used one-turn RDTs. Also, reducing the third-order RDT fluctuations is beneficial for controlling the fourth-order RDTs and ADTS terms. Then we use it as an objective to optimize the nonlinear dynamics and good results are obtained.
Paper: WEPL078
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL078
About: Received: 30 Apr 2023 — Revised: 04 May 2023 — Accepted: 11 May 2023 — Issue date: 26 Sep 2023
WEPL093
Phase space control of transverse resonance island buckets at CESR
3317
Transverse resonance island buckets (TRIBs) have been successfully observed at the Cornell Electron Storage Ring (CESR) after optimizing the distribution of seventy-six sextupoles to achieve the desired amplitude-dependent tune shift and the resonant driving term near a third-order resonant line (3vx=2). A novel knob is created to adjust the resonant driving term h22000 while minimizing the change of h30000. Interestingly found from simulation, the knob can change the TRIBs locations in the phase space, which is then confirmed experimentally at CESR. Theoretical calculation of the fixed points (stable and unstable) in the phase plots are explored with PTC, which shows excellent agreement with the tracking results and provides theoretical understanding of the TRIBs in the phase space. In addition, the island locations in the real x-y space are explored by adjusting a skew quadrupole to change the x-y coupling.
Paper: WEPL093
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL093
About: Received: 01 May 2023 — Revised: 10 May 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
WEPL096
Analysis of a double-resonance crossing for beam splitting
3325
Beam splitting can be performed by adiabatic crossing of a given one-dimensional non-linear resonance. This process is routinely used at the CERN PS to deliver the proton beam to the SPS fixed-target physics. To improve the efficiency of the intensity sharing between the various beamlets, a dipole kicker can be used to excite the beam during the resonance crossing process. This entails a double-resonance crossing phenomenon that will be described and discussed in detail in this paper.
Paper: WEPL096
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL096
About: Received: 02 May 2023 — Revised: 05 May 2023 — Accepted: 15 Jun 2023 — Issue date: 26 Sep 2023
WEPL097
The adiabatic theory of the nonlinear coupling resonance crossing in circular accelerators
3329
In this paper, the nonlinear coupling resonance $2 Q_x -2 Q_y = 0$ is studied by means of a Hamiltonian model. The detailed analysis of its phase-space topology unveils the possible phenomena that can occur when crossing adiabatically such a resonance. These considerations are probed by means of numerical simulations carried out using a symplectic map and the results are presented and discussed in detail.
Paper: WEPL097
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL097
About: Received: 02 May 2023 — Revised: 05 May 2023 — Accepted: 11 May 2023 — Issue date: 26 Sep 2023
WEPL098
Numerical simulations of transverse nonlinear beam manipulations at the CERN PS
3333
A new set of nonlinear beam manipulations have been recently proposed, with the goal of extending the transverse beam splitting that is routinely used at the CERN PS to deliver beam to the SPS for fixed-target physics. Using a simple Hamiltonian model, it has been shown how the transverse emittances can be shared by crossing a two-dimensional nonlinear resonance. Moreover, it has been shown how an AC-dipole can be used to split transversely the beam. In this paper, numerical simulations of these manipulations performed using a realistic model of the PS ring, including longitudinal motion, will be presented and discussed in detail.
Paper: WEPL098
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL098
About: Received: 03 May 2023 — Revised: 05 May 2023 — Accepted: 11 May 2023 — Issue date: 26 Sep 2023
WEPL109
Further investigations of TRIBs in BESSY III design MBA lattices
3363
This paper is the follow-up of a previous one where we reported symmetry breaking as the main factor that establishes transverse resonance island buckets (TRIBs) close to a third-order random resonance in one of BESSY III design lattices by using a single knob. Here we present a more complete picture of the analytical framework and we show that there are two types of resonances close to which islands can be implemented. We give a brief overview of how this framework can be applied by using the BESSY III multibend-achromat (MBA) lattices as examples.
Paper: WEPL109
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL109
About: Received: 03 May 2023 — Revised: 08 May 2023 — Accepted: 11 May 2023 — Issue date: 26 Sep 2023
WEPL112
Simultaneous Compensation of Third-Order Resonances at the FNAL Recycler Ring
3375
Third-order resonance lines will have a detrimental effect on the high-intensity operation of the Recycler Ring (RR), under the current Proton Improvement Plan (PIP-II) for the Fermilab Accelerator Complex. Increasing intensity will increase space charge effects, leading to the excitation of normal and skew sextupole lines. Dedicated normal and skew sextupoles have been installed in order to mitigate the effect of these resonance lines. By measuring the response matrix of the third-order Resonance Driving Terms (RDTs) to the currents of these dedicated elements, this study shows how several resonance lines can be compensated simultaneously. Resonance compensation is experimentally verified through loss maps and emittance growth measurements using the Ion Profile Monitor (IPM) system in the Recycler.
Paper: WEPL112
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL112
About: Received: 03 May 2023 — Revised: 08 May 2023 — Accepted: 15 Jun 2023 — Issue date: 26 Sep 2023
WEPL116
Analytic calculations of RDT and detuning generated by beam-beam collisions and wire correctors
3383
Formulae to compute the footprint (amplitude-dependent detunings) and Resonance driving terms RDT, generated by long-range beam-beam collisions and wire correctors have been implemented in a Python code. The paper briefly outlines the method and code and provides several examples of its usage. The maximum extent of the footprint (in geometric sense) can be efficiently computed.
Paper: WEPL116
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL116
About: Received: 05 May 2023 — Revised: 08 May 2023 — Accepted: 15 Jun 2023 — Issue date: 26 Sep 2023
WEPL121
Dispersion relations for a cylindrical waveguide with multilayer walls
3395
An algorithm for determining the eigenvalues of the eigenfunctions of a multilayer cylindrical waveguide is constructed. A relationship is found between dispersion relations and impedances. A method for determining the resonant frequencies of the wake field in the linear and helical motion of a particle is described. The damping coefficients of eigenmodes at resonant frequencies are determined.
Paper: WEPL121
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL121
About: Received: 04 May 2023 — Revised: 06 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
WEPL150
Characterization of the longitudinal beam coupling impedance and mitigation strategy for the fast extraction kicker KFA79 in the CERN PS
3458
In the framework of the High Luminosity Upgrade of the LHC (HL-LHC) the beam intensity from the injectors must be doubled while keeping longitudinal beam parameters unchanged. As such, high-quality beams with high intensities are required also from the Proton Synchrotron (PS). The beam coupling impedance plays a crucial role and mitigation measures must be taken to remain within a stringent impedance budget. Kicker magnets are important contributors to the overall broadband impedance of the PS. Moreover, the detailed study of kicker impedances revealed additional resonant modes which may be critical for the beam stability. The longitudinal beam coupling impedance for the fast extraction kicker KFA79 is presented in this study, and a solution to reduce the impedance of the critical resonant modes is introduced. Electromagnetic (EM) simulations have been performed to determine the impedance behaviour. Finally, the insertion of transition pieces between magnet modules is presented as a measure for mitigating the low frequency resonant impedance contributions.
Paper: WEPL150
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL150
About: Received: 03 May 2023 — Revised: 11 May 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
WEPL153
Impedance analysis of deformable RF contact bridges for high luminosity LHC
3470
In order to maintain the continuity of the vacuum system wall and comply with beam stability limits, radio frequency contact bridges are utilised as transitional elements in beam vacuum line interconnections. These radio frequency contact bridges must absorb and correct longitudinal, angular, and transverse misalignments brought on by mechanical motions during assembly, alignment, operating phases and thermal influences during accelerator operation. A deformable thin-walled copper beryllium structure is the foundation of a novel deformable radio frequency contact bridge concept that satisfies the above criteria without using conventional sliding contacts. To assess the feasibility of implementing such deformable radio frequency contact bridges in the High-Luminosity LHC, the longitudinal, dipolar, and quadrupolar components of the beam impedance in the two transverse planes were determined using electromagnetic simulations.
Paper: WEPL153
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL153
About: Received: 06 Apr 2023 — Revised: 08 Jun 2023 — Accepted: 08 Jun 2023 — Issue date: 26 Sep 2023
WEPL157
Beam-induced heating mitigation of the SPS kickers: a crucial upgrade to move towards HL-LHC beam intensities
3486
Beam-induced heating of equipment can have several undesirable effects, including rendering the equipment temporarily inoperative, equipment degradation and/or damage. Hence, to avoid these problems, it can be necessary to limit beam intensity. Beam-coupling impedance mitigation of existing devices and/or design optimization of new accelerator elements are essentials to overcome these limitations. In this framework a very good example is the optimization of the SPS kickers beam-coupling impedance for beam-induced heating mitigation. This paper describes the beam-coupling impedance measurements and simulation studies performed to identify and potentially remove the intensity limitation arising from the excessive beam-induced heating of a SPS injection kicker.
Paper: WEPL157
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL157
About: Received: 03 May 2023 — Revised: 09 May 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
WEPL189
Simulation studies on longitudinal beam dynamics manipulated by corrugated structures under different bunch length conditions at KARA
3570
In the KIT storage ring KARA (Karlsruhe Research Accelerator), two parallel plates with periodic rectangular corrugations are planned to be installed. These plates will be used for impedance manipulation to study and eventually control the electron beam dynamics and the emitted coherent synchrotron radiation (CSR). In this contribution, we present simulation results showing the influence of different corrugated structures on the longitudinal beam dynamics and how this influence depends on the machine settings in the low momentum compaction regime, which are related to the bunch length changes.
Paper: WEPL189
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL189
About: Received: 02 May 2023 — Revised: 10 May 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
WEPL192
Ion trapping and instabilities in SLS 2.0
3578
Residual gas atoms, ionized by the electron beam, may create two effects in an electron accelerator. One is the trapping of ions in the beam channel by the Coulomb forces of the beam and the other is the fast beam ion instability, a dynamic mutual transverse oscillation between ions and electrons. While the strongly reduced beam emittance of the accelerator upgrade SLS 2.0 is helpful in that situation, it will not suppress ion related effects completely. To avoid ion trapping, a small ion clearing gap of 30 buckets is still required. Enlarged pressures of 1e-9 mBar, as expected before complete vacuum conditioning, may lead to sufficient build up of ions during the passage of the bunch train to provoke fast beam ion instabilities, requiring to employ multiple clearing gaps. At nominal conditions with 1e-10 mBar, a stable operation is expected.
Paper: WEPL192
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL192
About: Received: 26 Apr 2023 — Revised: 05 May 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
WEPM008
Efficient RF components of solid-state amplifiers for Sirius storage ring's RF plant
3586
Solid-state RF amplifiers (SSAs) are being developed to compose SIRIUS storage ring’s RF plant for operation with superconducting cavities. Each amplifier must deliver up to 65 kW of RF power at 500 MHz and a high AC-to-RF efficiency is desired to minimize operation costs. To this end, amplifier modules able to deliver 900 W with approximately 70 % DC-to-RF efficiency were designed. To combine the output of 80 modules, a cavity combiner was simulated and a prototype was assembled. This paper presents the performance of the RF modules obtained from a pilot batch, as well as measurement results from the cavity combiner at low RF power. Finally, a summary on the ongoing development of solid-state amplifiers is presented.
Paper: WEPM008
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPM008
About: Received: 03 May 2023 — Revised: 18 May 2023 — Accepted: 23 Jun 2023 — Issue date: 26 Sep 2023
WEPM013
HPRF SSPA System for RAON SRF cavities
3596
The heavy-ion accelerator of the Rare Isotope Science Project (RISP) in Korea has been developed. There are three types of SRF cavity, which are 81.25MHz quarter-wave resonator (QWR), 162.5MHz half-wave resonator (HWR), 325MHz single-spoke resonator (SSR). There are 22 QWRs and 102 HWRs in the superconducting linac#3 (SCL3), and 69 SSR1s and 144 SSR2s in the superconducting linac#2 (SCL2). The required RF power is 4kW for each QWR, 4kW for each HWR, 8kW for each SSR1, and 20kW for each SSR2. The high power RF SSPAs for the SRF cavities have been developed and fabricated with domestic companies. 325MHz 20kW SSPAs have been designed and fabicated to test the prototype of the SSR2 SRF cryomodule including six SSR2 cavities. They were designed to enable full-reflection operation at all times. It consists of four 6kW power-units, four 6kW circulator units, 4-way combiner, a control unit, a power distribution unit, and cooling water inlet/outlet manifolds in each 19“ rack. The power-unit has six 1.2kW pallets and circulators, and three power packs. This paper describes the design and fabrication of the SSPA systems for the RAON SRF cavities.
Paper: WEPM013
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPM013
About: Received: 28 Apr 2023 — Revised: 07 May 2023 — Accepted: 11 May 2023 — Issue date: 26 Sep 2023
WEPM078
A two harmonics circuit for the powering of the very fast RCS (Rapid Cycling Synchrotron) of the muon collider accelerator
3746
Acceleration for a muon collider will have to be extremely fast to ensure efficient transmission of the decaying beams, with acceleration times of the order of 1ms. One of the proposals for such a machine is centered around a rapid cycling synchrotron (RCS), a hybrid lattice of cells with alternating superconducting and resistive dipole magnets. Resistive magnets will swing from negative to positive field level, providing the magnetic flux variations (more than 3600 T/s) that are required for the quick acceleration of the muons, while the superconducting magnets will give a field offset. The resistive magnets will have to be supplied with extremely high peak power levels, in the order of few tens of GW, to provide the necessary magnetic field variations. For the extremely quick magnetic field ramp, this application is unique in the field of the RCS and related technologies. This paper analyses the application of a two harmonics circuit with additional active filter to the powering of the four RCS stages of the muon acceleration to the ultimate 10 TeV energy level
Paper: WEPM078
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPM078
About: Received: 10 May 2023 — Revised: 11 May 2023 — Accepted: 15 Jun 2023 — Issue date: 26 Sep 2023
WEPM137
Study on XiPAF-upgrading synchrotron beam loss
3899
Xi'an 200MeV proton application Facility, as known as XiPAF, is upgraded to a heavy ion synchrotron, which replace H^- stripping injection with multiturn injection scheme. New synchrotron circumference is much bigger than original one for injection equipment installation space, which means that this heavy-ion lattice is much different from original proton lattice. Simulation is performed with pyorbit for resonance beam loss study, with or without space charge effect, the main beam loss is caused by 3-order incoherent resonance, i.e. vx+2vy=6, which is a structure resonance. Space charge and longitudinal synchrotron motion accelerate the beam loss process.
Paper: WEPM137
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPM137
About: Received: 30 Apr 2023 — Revised: 18 May 2023 — Accepted: 18 May 2023 — Issue date: 26 Sep 2023
THOGA3
Using P-Spice model for spark detection in TRIUMF's main cyclotron system
3920
Sparks in TRIUMF's main cyclotron have to dissipate a lot of energy due to the large volume of the RF cavity, causing a trip of the system, resulting in down time of the machine and provide a risk of damaging the system if not reacted to immediately. A spark detection system evaluating the rate of change of the reversed power signal within the cyclotron when a spark occurs is employed but can currently not provide any information about its location. Simulations with a detailed P-spice model including the entire RF infrastructure from the amplifier, the combiner station, the waveguide system, and the rather big cyclotron with a diameter of 18 meters will provide the necessary information whether the location of a spark in the system can be located. The evaluated signals are the rate of change of the falling DEE voltage and the RF signals in different locations of the RF system. These results and actual measurements of sparks in the system can then in the future be used to train a Machine Learning model to implement a real time spark detection and reaction system. Such a system provides fast diagnostics and enables preventative maintenance during scheduled maintenance times and hence can reduce the machine downtime significantly.
Paper: THOGA3
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THOGA3
About: Received: 02 May 2023 — Revised: 05 May 2023 — Accepted: 23 Jun 2023 — Issue date: 26 Sep 2023
THPA059
Upgrades and developments related to stable ion beams injectors at INFN-LNL
4093
The LNL accelerator complex is equipped with two stable ion beams injectors, employing respectively negative and positive ion sources. In particular, a sputtering-type negative ion source and an Electron Cyclotron Resonance Ion Source (ECRIS) are installed on high voltage platforms, to provide the optimum injection energy in the downstream accelerators. Recently, the two injectors have been object of upgrades and developments, in order to improve the overall safety and reliability of the two systems, as well as the beams available for the users. This contribution describes the work related to the above mentioned activities, the technical choices employed and the latest results on ion beams production.
Paper: THPA059
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPA059
About: Received: 08 May 2023 — Revised: 18 May 2023 — Accepted: 22 Jun 2023 — Issue date: 26 Sep 2023
THPA079
Characterization and optimization of laser-generated THz beam for THz based streaking
4149
At the Ferninfrarot Linac- und Test-Experiment (FLUTE) at the Karlsruhe Institute of Technology (KIT) a new and compact method for longitudinal diagnostics of ultrashort electron bunches is being developed. For this technique, which is based on THz streaking, strong electromagnetic pulses with frequencies around 240 GHz are required. Therefore, a setup for laser-generated THz radiation using tilted-pulse-front pumping in lithium niobate was designed, delivering up to 1 µJ of THz pulse energy with a conversion efficiency of up to 0.03 %. In this contribution we study the optimization of the THz beam transport and environment.
Paper: THPA079
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPA079
About: Received: 02 May 2023 — Revised: 05 Jun 2023 — Accepted: 22 Jun 2023 — Issue date: 26 Sep 2023
THPA090
A MTCA.4-based resonance controller for superconducting cavities
4164
The growing interest in upgrading European XFEL to high duty cycle operation requires an adaptation of the current low-level RF system to the new machine specifications. In the current upgrade scenario, the principal change in the RF parameters will be the loaded quality factor (QL) of the superconducting cavities, which will increase from the current value of 4.6e6 to more than 5.3e7 to reduce the required RF power. As a result, the accelerating system will be an order of magnitude more sensitive to detuning disturbances, such as Lorentz force detuning or external microphonic vibrations. Therefore an MTCA.4-based chain to precisely measure the cavity RF signals, calculate the detuning error, generate a control signal and drive the piezoelectric tuner was developed both for single cavity and Vector Sum mode of operation. While the detuning measurement chain is implemented in programmable logic, the control algorithms are implemented on embedded processing systems of FPGA-enabled devices like DAMC-FMC25, DAMC-FMC1Z7IO, and DAMC-FMC2ZUP MTCA AMCs. This provides a flexible platform to develop resonance control algorithms. In this proceeding, the implemented architecture is discussed.
Paper: THPA090
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPA090
About: Received: 02 May 2023 — Revised: 06 May 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
THPA099
FAIR SIS100 Accelerating RF System - Modeling and Analysis of the Coupled LLRF Control Loops
4190
The SIS100 heavy ion synchrotron as core part of the Facility for Antiproton and Ion Research (FAIR) will be equipped with 14 accelerating RF stations in the first stage of realization. Each RF station consists of a tunable ferrite-loaded cavity powered by a tetrode amplifier. Further key components are a solid-state pre-amplifier, a power supply unit, and dedicated Low-Level Radio Frequency (LLRF) feedforward and feedback systems to control amplitude and phase of the cavity gap voltage as well as the resonance frequency. Each cavity has to provide up to 20 kV peak gap voltage in the frequency range from 1.1 to 3.2 MHz. While all components of the system have been successfully tested in the factory acceptance tests and transferred to the FAIR storage, the First-of-Series (FoS) RF station is still persistently operated at GSI to gain experience. For further insight into the LLRF part, especially the stability of the control loops, the inter-coupling of the three local control loops was analyzed with methods from control theory based on simplified but realistic models, which have been developed based on extensive measurements and analysis of the systems’ behavior. In this contribution, the modeling as well as the analysis of the coupling between the LLRF control loops are discussed and the results are presented in comparison with measurements on the FoS system.
Paper: THPA099
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPA099
About: Received: 03 May 2023 — Revised: 10 May 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
THPA108
Tuner loop based on FPGA for Petra cavity at TPS booster ring
4216
The low level RF system of TPS booster ring was replaced by the DLLRF in 2018. After that, the phase drift compensation loop for energy saving operation and the tuner loop were also implemented into the DLLRF system sequentially. We used altera-DE3 to build the core of DLLRF and to handle the high speed ADC/DAC procedure for RF signal sampling. As facing to the tuner control requirement, we choose an another low cost board, altera-DE0-Nano, to develop the tuner loop for 5-Cells-Petra-Cavity. It has an eight channels 12-bits-ADC, ADC128S022, to detect two tuners’ positions and two transmit powers for power balance function. The phase information of forward power and cavity gap voltage will get from altera-DE3 to tell the tuner loop in altera-DE0-Nano that the cavity is resonance or not. The tuner loop controls the cavity to work not only at resonance frequency but also with balance electric field distribution. In this study, the architecture of the tuner loop is presented including locking resonance frequency and field balance functions. The performance of field balance function is observed by the archive data of two tuners’ positions and two transmit powers.
Paper: THPA108
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPA108
About: Received: 25 Apr 2023 — Revised: 11 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
THPA137
RF characterisation of laser treated copper surfaces for the mitigation of electron cloud in accelerators
4275
In accelerator beam chambers and RF waveguides, electron cloud and multipacting can be mitigated effectively by reducing the secondary electron yield (SEY). In recent years, it has been established that laser surface structuring is a very efficient method to create a copper surface with SEY close to or even below unity. Different laser pulse durations, from nanoseconds to picoseconds, can be used to change surface morphology. Conversely, the characteristics that minimise the SEY, such as the moderately deep grooves and the redeposited nanoparticles, might have unfavourable consequences, including increased RF surface resistance. In this study, we describe the techniques used to measure the surface resistance of laser-treated copper samples using an enhanced dielectric resonator with 12 cm diameter sample sizes operating in the GHz range. The quantification basis lies in a non-contact measurement of the high-frequency losses, focusing on understanding the variation of surface resistance levels depending on the specifics of the treatment and possible post-treatment cleaning procedures.
Paper: THPA137
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPA137
About: Received: 10 May 2023 — Revised: 11 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
THPL035
Identification of magnetic field errors in synchrotrons based on deep lie map networks
4499
Magnetic field errors pose a limitation in the performance of circular accelerators, as they excite non-systematic resonances, reduce dynamic aperture and may result in beam loss. Their effect can be compensated assuming knowledge of their location and strength. Procedures based on orbit response matrices or resonance driving terms build a field error model sequentially for different accelerator sections, whereas a method detecting field errors in parallel yields the potential to save valuable beamtime. We introduce deep Lie map networks, which enable construction of an accelerator model including multipole components for the magnetic field errors by linking charged particle dynamics with machine learning methodology in a data-driven approach. Based on simulated beam-position- monitor readings for the example case of SIS18 at GSI, we demonstrate inference of location and strengths of quadrupole and sextupole errors for all accelerator sections in parallel. The obtained refined accelerator model may support set up of corrector magnets in operations to allow precise control over tunes, chromaticities and resonance compensation.
Paper: THPL035
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL035
About: Received: 29 Apr 2023 — Revised: 10 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
THPL047
RF system on a chip: a compact controller for SRF cavity field and detuning control
4532
For SRF cavity systems operated in continous wave (CW) at low effective beam loading as in Energy Recovery Linacs or Free Electron Lasers with rather low beam current, control of the tuning and counteracting any detuning caused by microphonics or Lorentz force driven coupled ponderomotive instability is mandatory to deliver and preserve a stable beam in longitudinal phase space regime. To develop beyond the currently employed mTCA based LLRF systems, a compact RF on a chip system was developed, which features several potential applications. Those range from a digital PLL to test and characterize the RF performance of cavities to a selection of detuning control algorithms, we have worked on in recent years, as e.g. a Kalman filter based state estimator controller [1] or an adaptive feedforward algorithm [2]. Here, we will show our first experimental findings with a TESLA style nine-cell SRF cavity operated in CW at our horizontal test facility HoBiCaT.
Paper: THPL047
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL047
About: Received: 03 May 2023 — Revised: 12 Jun 2023 — Accepted: 12 Jun 2023 — Issue date: 26 Sep 2023
THPL048
Quantum efficiency and lifetime study for negative electron affinity GaAs nanopillar array photocathode
4536
Recent studies showed significant improvement in quantum efficiency (QE) by negative electron affinity (NEA) GaAs nanopillar array (NPA) photocathodes over their flat surface peers, particularly at 500 ─ 800 nm waveband. However, the underlying physics is yet to be well understood for further improvement in its performance. In this report, NEA GaAs NPA photocathodes with different dimensions were studied. The diameter of the nanopillars varied from 200 ─ 360 nm, the height varied from 230 ─ 1000 nm and the periodicity varied from 470 ─ 630 nm. The QE and photocathode lifetime were measured. Mie-resonance enhancement was observed at tunable resonance wavelengths. Simulations was also performed to understand the mechanism of photo-absorption and possible ways to further improve the photocathode performance to meet the stringent requirement of the electron sources in large scale electron accelerators. **Acknowledgement** Authored by Jefferson Science Associates, LLC under U.S. DOE contract no. DE-AC05-06OR23177. The U.S. Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce this manuscript for U.S. Government purposes. *mrahm008@odu.edu
Paper: THPL048
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL048
About: Received: 09 May 2023 — Revised: 11 May 2023 — Accepted: 15 Jun 2023 — Issue date: 26 Sep 2023
THPL052
Resonant Cavity for Beam Current Diagnostics in Medical Accelerators
4550
Beam currents of particle accelerators used for cancer treatment are often on the nanoampere level. These currents are too low for standard beam current diagnostics used in other fields of particle accelerator science, e.g. current transformers. This led to the general adoption of ionization chambers for beam current and dose rate determination in medical accelerators. However, the development of the so-called FLASH radiation therapy requires beam currents too high for normal ionization chambers yet still too low for standard current transformers. Resonant cavities have shown their capability to precisely detect nanoampere to microampere beam currents which renders them interesting for FLASH radiation therapy accelerators. After the design of a resonant cavity at Paul Scherrer Institut (PSI), a collaboration between PSI, Instrumentation Technologies, and Bergoz Instrumentation was established with the goal to develop a complete turn-key beam current diagnostics system readily available for medical accelerators. Two prototype systems were manufactured, installed, and tested at PROSCAN/PSI. We discuss the layout of the measurement systems and compare expected performance to beam current measurements.
Paper: THPL052
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL052
About: Received: 28 Apr 2023 — Revised: 10 May 2023 — Accepted: 22 Jun 2023 — Issue date: 26 Sep 2023
THPL122
Split-ring resonator experiments and data analysis at FLUTE
4760
FLUTE (Ferninfrarot Linac- Und Test-Experiment) is a compact linac-based test facility for accelerator and diagnostics R&D located at the Karlsruher Institute of Technology (KIT). A new accelerator diagnostics tool, called the split-ring resonator (SRR), was tested at FLUTE, which aims at measuring the longitudinal bunch profile of fs-scale electron bunches. Laser-generated THz radiation is used to excite a high frequency oscillating electromagnetic field in the SRR. Electrons passing through the 20 µm x 20 µm SRR gap are time-dependently deflected in the vertical plane, leading to a vertical streaking of the electron bunch. During the commissioning of the SRR at FLUTE, large series of streaking attempts with varying machine parameters and set-ups were investigated in an automatized way. The recorded beam screen images during this experiment have been analyzed and evaluated. This contribution motivates and presents the automatized experiment and discusses the data analysis.
Paper: THPL122
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL122
About: Received: 02 May 2023 — Revised: 09 May 2023 — Accepted: 11 May 2023 — Issue date: 26 Sep 2023
THPL183
Optimization and development of the CBPM system for the SHINE
4876
Beam-based alignment and feedback systems are essential for the operation of the Free Electron Lasers (FELs). Cavity BPMs having the advantage of high position resolution are widely used in the field of accelerators. Systematically analyze the impact of the key parameters of each subsystem on the performance of the whole system, so that the key technical indicators of each subsystem can achieve the optimal and balanced allocation, is the primary issue to be considered when designing a CBPM system. In this paper, the relationship between the relative amplitude extraction uncertainty of the CBPM system and the key parameters of each subsystem is proposed based on theoretical analysis. And this method has also been applied in the development of the CBPM system for the Shanghai High repetition rate X-ray Free Electron Laser and Extreme Light facility (SHINE). Based on the beam test bench in the Shanghai Soft X-ray FEL facility (SXFEL), the position measurement uncertainty of the CBPM system can reach 40 nm at the bunch charge of 100 pC, which is consistent with the theoretical analysis results and better than the requirements of the SHINE.
Paper: THPL183
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL183
About: Received: 03 May 2023 — Revised: 10 May 2023 — Accepted: 22 Jun 2023 — Issue date: 26 Sep 2023
THPL192
Simulations of the compact transverse-deflecting system for ultra-short electron bunch diagnostic
4887
A compact TDS (transverse-deflecting system) has been proposed for diagnostics of extremely short electron bunches (up to single-digit femtosecond range). The main idea is to use terahertz radiation, produced from optical rectification of the facility’s electron gun laser pulse. This provides an intrinsic synchronization between the electron bunch and the laser pulse. The proposed system is to be constructed at the test facility FLUTE (Ferninfrarot Linac- und Test-Experiment) at Karlsruher Institut für Technologie (KIT), which provides the opportunity to create electron bunches of variable length and at medium energy (7 MeV up to 90 MeV). Simulations in CST MICROWAVE STUDIO are carried out in parallel with the experimental activities to optimize the design of the system. In the present paper the simulation results for several possible designs will be presented.
Paper: THPL192
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL192
About: Received: 02 May 2023 — Revised: 12 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
THPM021
Laser powder bed fusion of pure niobium for particle accelerator applications
4935
Niobium is particularly appreciated for its superconductive properties. One of the main applications of this metal in Nuclear Physics is the production of superconducting radiofrequency (SRF) cavities for particle accelerators. Additive Manufacturing (AM) gives the chance to fabricate objects with very complex shapes; also, high melting temperature and hard-to-machine materials can be easily processed. However, AM is not free from challenges, and the creation of devices such as the SRF cavities is not trivial. In this work, the characterization of pure niobium produced by Laser Powder Bed Fusion (LPBF) and a fine-tuning of the printing parameters have been carried out. Much emphasis was put on the development of innovative contactless supporting structures for improving the quality of downward-facing surfaces with very small inclination angles. A relative density higher than 99.8% was achieved and the efficiency of such innovative supports was demonstrated, as they made the fabrication of seamless SRF cavities possible. Smoothing surface treatments and performance tests on AMed cavities were also performed.
Paper: THPM021
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPM021
About: Received: 04 May 2023 — Revised: 10 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
THPM037
S-Band Accelerating Cells Geometry RF Measurements Technique for Pre-Tuning and Smart Combination
4971
The upgrade program for AREAL accelerator includes beam energy increase from 5 MeV up to 50 MeV. For this purpose, two 43 cells, and 1.6 m long, S-band accelerating structures are foreseen. The design and fabrication of cells are already carried out in CANDLE. For effective acceleration the tuning of phase advance and frequency of the structure is necessary. The precise geometrical dimension measurements to pick the proper sequence of cells are necessary to minimize accelerator structure tuning routine after brazing. In this paper, a method for cell geometry precise measurements is presented. The method based on TM resonance frequencies measurement for radius and length variation evaluation in µm range. The µm variation driving resonance frequency shift by few tens’ kHz, which is measurable by conventional VNA. The theoretical basis and experimental results for AREAL 50 MeV upgrade accelerator structures cells are presented.
Paper: THPM037
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPM037
About: Received: 01 May 2023 — Revised: 07 May 2023 — Accepted: 11 May 2023 — Issue date: 26 Sep 2023