BNL, Upton, Long Island, New York, USA
Measurements of amplitude-dependent tune shift are critical for understanding of nonlinear single particle dynamics in storage rings. The conventional method involves scanning of the kicker amplitude while having a short bunch train at the top of the kicker pulse. In this paper we present a novel, alternative technique that uses a long continuous bunch train, or a sequence of bunch trains, that are spread along the ring, such that different bunches experience different kick amplitudes with a single shot of a kicker pulse. With these beams, a curve of tune shift with amplitude can be extracted from the recently added new NSLS-II BPM feature called gated turn-by-turn (TbT) BPM data that can resolve bunches within a turn, either alone or together with a bunch-by-bunch BPM data. This technique is immune to pulse-to-pulse jitters and long-term machine drift.
ANL, Argonne, Illinois, USA
Fast fiber-optic (FFO) beam loss monitors (BLMs) installed with the first two superconducting undulators (SCUs) in the Advanced Photon Source storage ring have proven to be a useful diagnostic for measuring deposited charge (energy) during rapid beam loss events. The first set of FFOBLMs were installed outside the cryostat of the short SCU, a 0.33-m long device, above and below the beam centerline. The second set are mounted with the first 1.1-m-long SCU within the cryostat, on the outboard and inboard sides of the vacuum chamber. The next 1.1-m-long SCU is scheduled to replace the short SCU later in 2016 and will be fitted with FFOBLMs in a manner similar to original 1.1-m device. The FFOBLMs were employed to set timing and voltage for the abort kicker (AK) system. The AK helps to prevent quenching of the SCUs during beam dumps* by directing the beam away from the SC magnet windings. The AK is triggered by the Machine Protection System (MPS). In cases when the AK fails to prevent quenching, the FFOBLMs show that losses often begin before detection by the MPS.
K. Harkay et al., these proceedings
Fermilab, Batavia, Illinois, USA
Diversified Technologies, Inc., Bedford, Massachusetts, USA
Diversified Technologies, Inc. (DTI) has designed, built, and demonstrated a prototype pulse amplifier for stripline kicker service capable of less than 5 ns rise and fall times, 5 to 90 ns pulse lengths, peak power greater than 13.7 MW at pulse repetition rates exceeding 100 kHz, and measured jitter under 100 ps. The resulting pulse is precise and repeatable, and will be of great interest to accelerator facilities requiring electromagnetic kickers. The pulse generator is based on the original specifications for the NGLS fast deflector. DTI's planar inductive adder configuration uses compensated-silicon power transistors in low inductance leadless packages with a novel charge-pump gate drive to achieve unmatched performance. The unit was brought to LBNL, compared with other researcher's efforts, and was judged very favorably. A number of development prototypes have been constructed and tested, including a successful 18.7 kV, 749 A unit. The modularity of this design will enable configuration of systems to a wide range of potential applications in both kickers and other high speed requirements, including high performance radars, directed energy systems, and excimer lasers.
BNL, Upton, Long Island, New York, USA
Auburn University, Auburn, USA
A model to simulate the effect of a transverse feedback system is implemented in SPACE, a parallel, self-consistent code for collective effects. As an application, we discuss single bunch instability thresholds in the NSLS-II storage ring and compare the numerical results with measurements.
BNL, Upton, Long Island, New York, USA
First experience with the beam-induced heating of the ceramics chambers in the NSLS-II storage ring has been discussed. Total five ceramics chambers are considered to be replaced due to overheating concern during of upcoming Iav=500mA operations. The air cooling fans has been installed as a temporarily solution to remove heat.
BNL, Upton, Long Island, New York, USA
We re-consider stochastic cooling as type of information engine using the Adami definition of information *. We define information as data which can permit the cooling system to predict the individual trajectories better than purely random prediction and then act on that data to modify the trajectories of an ensemble of particles. In this study we track the flow of this type of information through the closed system and consider the limits based on sampling and correction as well as the role of the underlying model.
* Adami C. 2016 ‘‘What is information?'' Phil. Trans. R. Soc. A 374:20150230.
Northern Illinois University, DeKalb, Illinois, USA
Fermilab, Batavia, Illinois, USA
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
University of Washington, CENPA, Seattle, USA
Cornell University, Ithaca, New York, USA
Fermilab, Batavia, Illinois, USA
The new experiment, under construction at Fermilab, to measure the muon magnetic moment anomaly, aims to reduce measurement uncertainty by a factor of four to 140 ppb. The required statistics depend on efficient production and delivery of the highly polarized muon beams from production target into the g-2 storage ring at the design "magic"-momentum of 3.094 GeV/c, with minimal pion and proton contamination. We have developed the simulation tools for the muon transport based on G4Beamline and BMAD, from the target station, through the pion decay line and delivery ring and into the storage ring, ending with detection of decay positrons. These simulation tools are being used for the optimization of the various beam line guide field parameters related to the muon capture efficiency, and the evaluation of systematic measurement uncertainties. We describe the details of the model and some key findings of the study.
ANL, Argonne, Illinois, USA
A beam abort system has been implemented in the Advanced Photon Source storage ring. The abort system works in tandem with the existing machine protection system (MPS), and its purpose is to control the beam loss location and, thereby, minimize beam loss-induced quenches at the two superconducting undulators (SCUs). The abort system consists of a dedicated horizontal kicker designed to kick out all the bunches in a few turns after being triggered by MPS. The abort system concept was developed on the basis of single- and multi-particle tracking simulations using elegant and bench measurements of the kicker pulse. Performance of the abort system–kick amplitudes and loss distributions of all bunches–was analyzed using beam position monitor (BPM) turn histories, and agrees reasonably well with the model. Beam loss locations indicated by the BPMs are consistent with the fast fiber-optic beam loss diagnostics described elsewhere [1]. Operational experience with the abort system, various issues that were encountered, limitations of the system, and quench statistics are described.
[1] J. Dooling et al., these proceedings.
ANL, Argonne, Illinois, USA
A prototype dual-blade stripline kicker for the APS multi-bend achromat (MBA) upgrade has been designed and developed. It was optimized with 3D CST Micro-wave Studio. The high voltage (HV) feedthrough and air-side connector were designed and optimized. The elec-tromagnetic fields along the beam path, deflecting angle and high electric fields with their locations were calculat-ed with 15 kV differential pulse voltage applied to the kicker blades through the feedthroughs. The beam im-pedance and power dissipation on different parts of the kicker and external loads were studied for a 48-bunch fill pattern. Our simulation results show that the prototype kicker with its HV feedthroughs meets the specified re-quirements. The results of TDR (time-domain reflectome-ter) test, high voltage pulse test and beam test of the pro-totype kicker assembly agreed with the simulations.
ANL, Argonne, Illinois, USA
The APS multi-bend achromatic (MBA) upgrade storage ring plans to support two bunch fill patterns: a 48-bunch and a 324-bunch. A "swap out" injection scheme is required. In order provide the required kick to injected beam, to minimize the beam loss and residual oscillation of injected beam, and to minimize the perturbation to stored beam during injection, the rise, fall, and flat-top parts of the kicker pulse must be within a 16.9-ns interval. Stripling-type kickers are chosen for both injection and extraction. We developed a prototype kicker that supports a ±15kV differential pulse voltage. We performed high voltage discharge, TDR measurement, high voltage pulse test and beam test of the kicker. We report the design of the fast kicker and the test results.
IMP/CAS, Lanzhou, People's Republic of China
JLab, Newport News, Virginia, USA
A multi-frequency copper prototype cavity with 5 odd harmonic modes (from 95.26 MHz to 857.34 MHz) is fabricated and bench measured at JLab. This quarter wavelength resonator (QWR) based deflecting cavity is an half scale prototype of the five-mode cavity (from 47.63 MHz to 428.67 MHz) in the QWRs group developed for the ultrafast harmonic RF kicker in the proposed Jefferson Lab Electron Ion Collider (JLEIC, formerly MEIC). With this prototype cavity, several RF measurements are performed and the results show good agreement with the simulation results.