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SPEAR3, commissioned in 2004, is a third generation light source at the SLAC National Accelerator Laboratory. The low emittance lattice with an emittance of 10 nm had been operated for over a decade until the recent commission of the new lower emittance lattice with 7 nm emittance. The new lattice, based on the same double-bend achromat lattice, has pushed toward the design limit of such type of lattice in SPEAR3. In this paper, we will elaborate our commissioning experience for the new lattice in SPEAR3., Proceedings of the 13th International Particle Accelerator Conference, IPAC2022, Bangkok, Thailand

The Transverse Resonance Island Buckets have been studied at SPEAR3 as an option for timing experiment mode operation of this third generation synchrotron radiation facility. In this mode, with proper optics setting, the electron beam is populated to island orbits with the excitation from a kicker. In this paper, we will report the experimental observation of the beam dynamics with turn by turn beam position monitors and a fast gated camera. The results are also compared with tracking simulations., Proceedings of the 11th International Beam Instrumentation Conference, IBIC2022, Kraków, Poland

We present populating bunches into the transverse resonance islands buckets (TRIBs) on SPEAR3. As one of operation modes for the timing-mode or providing separated bunches in transverse direction, we are exploring TRIBs on SPEAR3. Experience and analysis on applying kicks multiple times using the bunch-by-bunch feedback kicker to move bunches into the TRIBs is described., Proceedings of the 13th International Particle Accelerator Conference, IPAC2022, Bangkok, Thailand

SPEAR3 is a third generation synchrotron radiation light source, which operates approximately 9 months each year with a very high reliability. The beam loss monitoring system in the storage ring has recently been upgrade to the modern Libera system from the original legacy hardware. During the initial stage of the new beam loss monitoring system deployment, it was proved to be useful for a new lattice commissioning at SPEAR3. In this paper, we will report the progress in the Libera system commissioning at SPEAR3 and present some first results., Proceedings of the 11th International Beam Instrumentation Conference, IBIC2022, Kraków, Poland

We present a lattice design for SSRL-X which is a green-field low-emittance storage ring proposal. The lattice is based on the hybrid multi-bend achromat and has natural emittance of 63 pm with 24-cells periodicity and ~570 m circumference under 3.5 GeV energy. Modification on dedicated cells which lengthens straight sections but keeps the phase advance is explored to further reduce the natural emittance by inserting damping wigglers., Proceedings of the 13th International Particle Accelerator Conference, IPAC2022, Bangkok, Thailand

In this paper, we first present the tracking studies for SPEAR3 with the new BL17 ID and estimate its impact on the dynamic aperture of the low emittance lattice. Then the ferrite dampers installations in the device is briefly reviewed. After that, we will show that, based on beam-based measurements, the performance of the dampers is as being expected from earlier numerical studies., Proceedings of the 12th International Particle Accelerator Conference, IPAC2021, Campinas, SP, Brazil

The new Multi-bunch feedback kickers have been designed to replace the current device loaned from ALS. In this paper, we first present the specification of the kickers based on the beam physics requirements. Then the mechanical design of the kicker is elaborated. Numerical simulations, both in time domain and in frequency domain, are conducted for evaluating the shunt impedance and beam coupling impedance of the kicker. Surface heating induced from the beam or the external source is estimated from the numerical results as well., Proceedings of the 12th International Particle Accelerator Conference, IPAC2021, Campinas, SP, Brazil

In this paper, we report the efforts in solving the problem of coupled-bunch instabilities caused by an in-vacuum undulator in the SPEAR3 storage ring. After exploring several approaches to reduce the strength of the trapped modes, we found that ferrite dampers were the most effective and simplest way for mode damping in our SPEAR3 in-vacuum undulator. The results of the first RF cold measurement on an in-vacuum undulator equipped with these ferrite dampers agree well with numerical simulations., Proceedings of the 10th Int. Particle Accelerator Conf., IPAC2019, Melbourne, Australia

Multi-bunch beam instabilities can often be controlled with high-speed digital bunch-by-bunch feedback systems. The detected motion is based on charge centroid measurements that, for short bunches, cannot resolve intrabunch charge dynamics. To compliment the BxB data, we installed a fast-gated camera with a rotating mirror to sweep visible-light synchrotron radiation across the camera CCD. The SR measurements present a complimentary view of the motion. For this work we generated transient beam events in SPEAR3 using the BxB feedback system and synchronously observed the motion on the camera. Results are presented for a high-order multibunch beam instability and for single bunch drive-damp experiments., Proceedings of the 7\textsuperscript{th} Int. Beam Instrumentation Conf., IBIC2018, Shanghai, China

Driven by the demand of suppressing transverse beam instabilities and developing novel short pulse operation modes in SPEAR3 storage ring, a wide-band transverse bunch-by-bunch feedback system has been recently commissioned for SPEAR3 storage ring. The system was demonstrated to be sufficient to suppress the transverse coupled bunch instabilities caused by trapped RF modes in one of the in vacuum insertion devices. A new function of beam instability interlock has been developed and is part of machine protection system for the in vacuum insertion device. In addition, the bunch-by-bunch feedback system serves as a indispensable diagnostic tool that enables us to measure machine parameters, beam impedance, and characteristics of the beam instability modes. In this paper, we describe the scheme and performance of the bunch-by-bunch feedback system at SPEAR3., Proceedings of the 10th Int. Particle Accelerator Conf., IPAC2019, Melbourne, Australia

The Delta undulator has been operated successfully in LCLS with full control of the polarization mode and K value of the device. In LCLS II, a new Delta II undulator will be based on a similar design but with some differences. In this paper, we will present numerical simulation results that provide guidance to choose the geometric shape of the magnet poles and define the required tolerance for assembling the undulator magnets., Proceedings of the 10th Int. Particle Accelerator Conf., IPAC2019, Melbourne, Australia

A new Septum magnet and chamber has been designed for the storage ring as a part of the accelerator improvement plan for operating a lower emittance lattice in SPEAR3. Therefore it is necessary to analyze the impedance effects on the beam from the new Septum chamber. Due to the complex design at the downstream transition of the Septum chamber, the longitudinal impedance is particular of concern. In this paper, we will present numerical simulation results for this particular component as well as the general analysis for the impedance effects of the whole chamber., Proceedings of the 10th Int. Particle Accelerator Conf., IPAC2019, Melbourne, Australia

Recently a transverse bunch-by-bunch feedback kicker was installed in SPEAR3 to control beam instabilities, remove unwanted satellite bunches and test resonant bunch excitation schemes for short pulse x-ray production. In conjunction with DIMTEL processing electronics, the feedback system can successfully stabilize undesirable beam modes and opens up the potential for more advanced investigations of bunch-by-bunch beam dynamics. To streamline the process, a graphical user interface was developed that allows the user to 'script' beam physics measurements from a single panel. At the press of a button the panel automatically downloads the measurement parameters, acquires the raw data and provides graphical displays of the beam response with calculated metadata. In this paper we present the interface format and examples of automated measurements., Proceedings of the 9th Int. Particle Accelerator Conf., IPAC2018, Vancouver, BC, Canada

The SPEAR3 timing system supplies a 10Hz trigger pulse synchronous with charge injection into the main storage ring. In the past the 10Hz pulse train has been used to study injected charge transients as seen by visible-light synchrotron radiation diagnostics and turn-by-turn BPMs. More recently the 10Hz pulse has been used to synchronize the bunch-by-bunch feedback data acquisition system with other triggered diagnostic systems. The suite of measurement systems can be used to study injected beam dynamics, grow/damp instability transients and drive/damp physics., Proceedings of the 9th Int. Particle Accelerator Conf., IPAC2018, Vancouver, BC, Canada

Vertical beam instabilities have been observed at SPEAR3 when a newly installed in-vacuum undulator (IVUN) is operated at a set of narrow gap settings. The source of the instabilities is believed to be vertically deflecting trapped modes inside the IVUN tank that are excited by the beam. We have used beam-based measurements to characterize the frequencies and strengths of the excited modes using both our bunch-by-bunch feedback system and a spectrum analyzer. Using numerical simulations of our IVUN structure, we have found modes with high shunt impedance near the measured frequencies. Recently, we have successfully measured these IVUN modes during our current downtime. In this paper, we will report on the measurements, simulations, and plans to damp these modes., Proceedings of the 5th Int. Beam Instrumentation Conf., IBIC2016, Barcelona, Spain

SPEAR3 operates with a large cross-section copper vacuum chamber, mode-damped RF cavities and low-impedance insertion devices. As a result, the beam is passively stable for 280-bunch circulating beam current up to 500ma when the background gas pressure is low. In the future, more small-gap insertion devices will be installed and plans are underway to implement resonant bunch-crabbing for the ultrafast x-ray research program. These requirements drive the need for a fast, bunch-by-bunch feedback system to control beam instabilities, remove unwanted satellite bunches and resonantly crab select bunches on demand. In this paper we present a conceptual design for the transverse bunch-by-bunch stripline kickers., Proceedings of the 8th Int. Particle Accelerator Conf., IPAC2017, Copenhagen, Denmark

Since its 2003 construction, the SPEAR3 synchrotron light source at SLAC has continuously improved its performance by raising beam current, top-off injection, small alpha and smaller emittance. This makes SPEAR3 one of the most productive light sources in the world. Now to further enhance the operation of SPEAR3, we are looking into the possibility of converting SPEAR3 to a multi-bend achromat storage ring within its site constraint., Proceedings of the 5th Int. Particle Accelerator Conf., IPAC2014, Dresden, Germany

Intrabeam scattering (IBS) can cause emittance growth in diffraction limited light sources. At lower beam energy, the IBS effect is expected to be more pronounced. To study these effects we have developed a series of low energy lattices in SPEAR3 with beam energy ranging from 3GeV to 700MeV. The horizontal beam size and bunch length are measured as a function of beam energy and compared with theoretic calculations., Proceedings of the 5th Int. Particle Accelerator Conf., IPAC2014, Dresden, Germany

The ability to produce short pulse X-rays on the scale of 1-10 ps fwhm in the SPEAR3 storage ring light source would enable enhanced timing mode studies of dynamic processes in materials as they occur. The crab cavity approach appears to be optimal for SPEAR3 to produce short pulse X-rays. Furthermore, by using a two-frequency crabbing scheme, SPEAR3 would be able to produce short-pulse bunches while supplying the high average flux needed for regular users. While supercon-ducting RF (SCRF) technology could be a natural choice for the CW crab cavity, the deflecting voltage for SPEAR3 crabbing appears to be within reach of more affordable normal conducting RF (NCRF). In this paper, we present a preliminary NCRF CW crab cavity design for SPEAR3., Proceedings of the 8th Int. Particle Accelerator Conf., IPAC2017, Copenhagen, Denmark