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We have developed and tested a technique, which significantly improves the accuracy of the orbit bump method of local impedance measurement. This technique is based on in-phase sine-wave (AC) excitation of four fast correctors adjacent to the vacuum chamber section, impedance of which is measured. The narrow-band sine-wave signals provide better signal-to-noise ratio. Use of fast correctors to the beam excitation eliminates the systematic error caused by hysteresis. The systematic error caused by orbit drift is also suppressed because the measured signal is not affected by the orbit motion outside the excitation frequency range. The measurement technique is described and the result of experimental testing carried out at NSLS-II is presented., Proceedings of the 6th Int. Beam Instrumentation Conf., IBIC2017, Grand Rapids, MI, USA

Two particle tracking codes, ELEGANT and SPACE, have been used to simulate the microwave instability in the APS storage ring. The total longitudinal wakepotential for the APS vacuum components, computed by GdfidL, has been used as the input file for the simulations. The numerical results have been compared with bunch length and the energy spread measurements for different single-bunch intensities., Proceedings of the North American Particle Accelerator Conf., NAPAC2016, Chicago, IL, 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 I_{a}v=500mA operations. The air cooling fans has been installed as a temporarily solution to remove heat., Proceedings of the North American Particle Accelerator Conf., NAPAC2016, Chicago, IL, USA

Several instability thresholds and special waveform beam pattern have been observed during measurements of the horizontal beam size change vs single bunch current by the synchrotron light monitor (SLM) camera installed in a low dispersion area of the NSLS-II storage ring. The electron beam energy spread from In-Vacuum Undulator (IVU) of the Soft Matter Interfaces (SMI) beam line confirmed the microwave beam pattern behavior as a current dependent effect. The numerically obtained total longitudinal wakepotential by the GdfidL code allowed us to compare the measured results with particle tracking simulations using the SPACE code. The instability thresholds behavior at different RF voltages are in some sort of overarching agreement., Proceedings of the 8th Int. Particle Accelerator Conf., IPAC2017, Copenhagen, Denmark

The Advanced Photon Source has proposed an upgrade to a multi-bend achromat (MBA) with a proposed timing mode calls for 48 bunches of 15 nC each. In this mode of operation we find that phase space mismatch from the booster can drive large wakefields that in turn may limit the current below that of the nominal collective instability threshold. We show that collective effects at injection lead to emittance growth that makes usual off-axis accumulation very challenging. On-axis injection ameliorates many of these issues, but we find that transverse feedback is still required. We explore the role of impedance, feedback, and phase-space mismatch on transverse instabilities at injection., Proceedings of the North American Particle Accelerator Conf., NAPAC2016, Chicago, IL, USA

We discuss measurements, performed in the NSLS-II storage ring, of the synchronous phase shift as a function of single bunch current from beam loading parameters. The synchronous phase is calculated from the forward and reflected power measured in the RF cavities. The comparison with direct synchronous phase measurements shows good agreement., Proceedings of the 8th Int. Particle Accelerator Conf., IPAC2017, Copenhagen, Denmark

The microwave instability in the NSLS-II has been studied for the current configuration of insertion devices, 9 In-Vacuum Undulators (IVU's), 3EPU's, 3 Damping Wigglers. The energy spread as a function of single bunch current has been measured based on the frequency spectrum of IVU for X-Ray Spectroscopy (SRX) beam line. The results for two lattices, bare lattice with nominal energy spread 0.0005 and a lattice with one DW magnet gap closed (nominal energy spread 0.0007) are compared. In addition we used a Spectrum Analyzer to measure the beam spectrum. The instability thresholds for two different lattices cross-checked numerically using the particle tracking code SPACE and longitudinal impedance., Proceedings of the North American Particle Accelerator Conf., NAPAC2016, Chicago, IL, 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., Proceedings of the North American Particle Accelerator Conf., NAPAC2016, Chicago, IL, USA

Single bunch instabilities have been observed since the early stage of NSLS-II storage ring commissioning. After installing the super-conducting cavity, the single bunch instability threshold current was similar at 0.7mA. The instability was eventually determined to be due to transverse mode coupling. Microwave instability has been characterized using streak camera bunch profile, horizontal beam sizes at dispersion location and beam spectrums. Microwave instability threshold current dependency on bunch lengths and IUV gaps has been studied. Most recent experimental results will be presented in this paper., Proceedings of the 7th Int. Particle Accelerator Conf., IPAC2016, Busan, Korea

Longitudinal bunch profile has been measured at NSLS2 storage ring using streak camera. From the measured profile, bunch lengthening and synchronous phase information can be derived to study the single bunch collective effect. Single bunch lengthening effect has been measured for bare lattice and for other lattices with different insertion devices. The streak camera can also be setup for other beam physics studies, for example to measure the injection beam dynamics and fast ion effects. Y-z imaging was measured using cylindrical lenses. Single bunch y-z profile was measured at threshold current., Proceedings of the 4th International Beam Instrumentation Conference, IBIC2015, Melbourne, Australia

The injector for the National Synchrotron Light Source II storage ring consists of a 3 GeV booster synchrotron and a 200 MeV S-band linac. The linac was designed to produce either a single bunch with a charge of 0.5 nC of electrons or a train of bunches up to 300 ns long containing a total charge of 15 nC. The booster was designed to accelerate up to 15 nC each cycle. Linac commissioning was completed in April 2012. Booster commissioning was started in November 2013 and completed in March 2014. All of the significant design goals were satisfied including beam emittance, energy spread, and transport efficiency. While the maximum booster charge accelerated was only 10 nC this has proven to be more than sufficient for storage ring commissioning. The injector has operated reliably during storage ring operation since then. Results will be presented showing measurements of injector operating parameters achieved during commissioning and initial operation. Operating experience and reliability during the first year of NSLS-II operation will be discussed., Proceedings of the 6th Int. Particle Accelerator Conf., IPAC2015, Richmond, VA, USA

As the newly constructed 3rd generation light source, NSLS-II is expected to provide the synchrotron radiation of ultra high brightness and flux with advanced insertion devices. To minimize the beam emittance, damping wigglers are used and the small aperture is located at the straight section with the damping wiggler and the corresponding vacuum camber is NEG coated. We used the local bump method to find the effect on the beam from the narrow aperture and the paper shows the results., Proceedings of the 6th Int. Particle Accelerator Conf., IPAC2015, Richmond, VA, USA

Understanding the sources of impedance is critical to accelerator design, and only becomes more important as vacuum chambers become smaller and closer to the electron beam. The multibend achromat upgrade at the Advanced Photon Source (APS) requires small, 22-mm diameter vacuum chambers and even smaller (6 mm) gaps for the insertion devices, so that both rf heating and wakefield-driven transverse instabilities become important concerns. We discuss modeling the primary sources of geometric impedance using the electromagnetic finite difference codes GdfidL and ECHO, and how these codes are influencing vacuum and accelerator component design., Proceedings of the 6th Int. Particle Accelerator Conf., IPAC2015, Richmond, VA, USA

The National Synchrotron Light Source II (NSLS-II) is a state of the art 3 GeV third generation light source at Brookhaven National Laboratory. As many facilities worldwide, NSLS II uses the EPICS control system to monitor and control all accelerator hardware. Control system studio (CSS) is used for simple tasks such as monitoring, display, setting of PVs. browsing the historical data, et. al. For more complex accelerator physics applications, a collection of scripts are mainly written in Python and part from Matlab during commissioning. With the close collaboration and fully support from control group, more and more CSS features were developed for operation convenience and several high level applications are interfaced with users in CSS panels for daily use based on softiocs. This paper will present the tools that we have been using for commissioning., Proceedings of the 6th Int. Particle Accelerator Conf., IPAC2015, Richmond, VA, USA

The typical problems occurring during commissioning of the first turns in the storage rings include shorted coils or reversed polarity of the magnets, cross-cabling of magnets power supplies and reversed polarity of BPMs. In this paper we describe a dedicated high level control application, which was created and utilized for commissioning of the first turns in NSLS-II storage ring., Proceedings of the 6th Int. Particle Accelerator Conf., IPAC2015, Richmond, VA, USA

A conceptual design has been developed for a radio frequency (rf) pickup-type beam position monitor (BPM) for use in a multi-bend achromat (MBA) storage ring under consideration by the APS Upgrade project (APS-U). Beam feedback systems are expected to require fourteen rf BPMs per sector with exceptional sensitivity and mechanical stability. Simultaneously, BPM insertion length must be minimized to allow lattice designers the greatest freedom in selecting magnet lengths and locations. Envisioned is a conventional four probe arrangement integrated inside of a pair of rf-shielded bellows for mechanical isolation. Basic aspects of the design are presented along with the results of analyses which establish expected mechanical, electronic, and beam physics-related performance measures., Proceedings of the 6th Int. Particle Accelerator Conf., IPAC2015, Richmond, VA, USA

An important operating mode for the multi-bend achromat (MBA) upgrade at the Advanced Photon Source (APS) calls for 200 mA average current divided evenly over 48 bunches. Ensuring that the desired 4.2 mA single bunch current can be stably stored requires a detailed understanding of the impedance in the MBA ring. We briefly discuss modeling sources of impedance using the electromagnetic codes GdfidL and ECHO, and how we then include both geometric and resistive wall wakefields using the tracking code elegant to predict collective instabilities. We first validate our procedures by comparing APS experimental measurements to tracking predictions using the APS storage ring impedance model. We then discuss the MBA impedance model, for which we find that a chromaticity of 5 units is sufficient to obtain the required 4.2 mA single bunch current. Finally, we mention certain design changes that may reduce the impedance and allow for a reduction in chromaticity., Proceedings of the 6th Int. Particle Accelerator Conf., IPAC2015, Richmond, VA, USA

In this paper we describe our experience with commissioning of the first turns in the NSLS-II storage ring. We discuss the problems that we encountered and show how applying a dedicated first turns commissioning software allowed us to diagnose and resolve these problems., Proceedings of the 6th Int. Particle Accelerator Conf., IPAC2015, Richmond, VA, USA

As another important milestone towards the final goal to store an average current of 500mA, the average current of 200mA, distributed within ~1000 bunches, was recently achieved in the NSLS-II storage ring after the installation of three Damping Wigglers and four In-Vacuum Undulators. First measurements of the collective effects and instability thresholds, both in single- and multi-bunch mode, are discussed., Proceedings of the 6th Int. Particle Accelerator Conf., IPAC2015, Richmond, VA, USA

The NSLS-II BPM Button design and its development process have been described. Subjects discussed include BPM Button impedance optimization, design and construction, production, BPM Button selection and a first temperature measurements at 200mA average current within 1200 bunches., Proceedings of the 6th Int. Particle Accelerator Conf., IPAC2015, Richmond, VA, USA

The NSLS-II storage ring has been commissioned during Phase 1 with 500 MHz 7-cell PETRA-III RF cavity. In this paper we present our first beam-measured data on instabilities and collective effects with a normal conducting RF system., Proceedings of the 5th Int. Particle Accelerator Conf., IPAC2014, Dresden, Germany

We discuss coupled-bunch instabilities thresholds for the NSLS-II Storage Ring. In particular, we analyze thresholds from the High Order Modes (HOMs) of the PETRA-III 7-cell cavity. Beam dynamics simulations with the code OASIS, using the measured HOMs, will be compared with machine studies., Proceedings of the 5th Int. Particle Accelerator Conf., IPAC2014, Dresden, Germany