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Since the Siam Photon Source (SPS) had an electron beam energy upgraded from 1.0 GeV to 1.2 GeV in 2005, the storage ring impedance measurements were done once in 2007. Two insertion magnet devices have been installed in the SPS storage ring during June to August 2013. There are several vacuum components added to the storage ring; these affect the ring impedance. Quantitative understanding of instabilities requires detailed knowledge of the impedance of the ring. For this purpose, the development of an impedance database is a necessity, where the wake potentials of each vacuum component are kept and maintained in a standard format. The self-describing data sets (SDDS) file format will be utilized to record components wake potentials. The wake potentials of each vacuum component can be obtained from a particle tracking simulation; a CST particle studio program will be used in the simulation process. The wake potentials can also be included in a beam dynamic tracking program such as ELEGANT to observe beam behaviors with these instabilities and find a curing means. The study results will be presented., Proceedings of the 13th International Particle Accelerator Conference, IPAC2022, Bangkok, Thailand

Siam Photon Source (SPS) machine in Thailand has been operating for more than two decades with limited diagnostic systems. It is very challenging to efficiently tune and operate the machine. With online optimization, only variables and objectives are required to tune for better solutions. It this work, a flexible optimizer was developed. Objectives and variables can be freely defined based on available hardware in the form of Process Variables (PVs). Several multi-objective and Robust Conjugated Direction Search (RCDS) algorithms are provided. The online optimizer was tested on the SPS machine to improved the injection efficiency. Due to its flexibility, the optimizer can also be used for other systems., Proceedings of the 13th International Particle Accelerator Conference, IPAC2022, Bangkok, Thailand

In order to provide synchrotron light with higher photon energy and more brilliant synchrotron light than that of the existing Siam Photon Source (SPS) machine, the possibility of constructing the new 3 GeV SPS-II has been proposed. For SPS-II, the synchrotron source with in-tunnel booster is a good candidate. The booster synchrotron has been designed in order to accelerate an electron beam of 150 MeV to 3 GeV before extracted to storage ring. For a clean injection in top-up operation, the aim in the design of the booster is to achieve the electron beam with a small emittance less than 10 nm-rad and to obtain a large dynamic aperture. The energy ramping process and related effects during the energy ramp are discussed in this paper., Proceedings of the 13th International Particle Accelerator Conference, IPAC2022, Bangkok, Thailand

At the Siam Photon Source (SPS) beam loss monitors based on PIN diode have been used. The existing system allow beam loss detection very locally at the monitor position close to the vacuum chamber. For optical fiber, Cherenkov radiation can be detected when a lost particle travel in the fiber. Thus optical fiber based loss monitor with sufficient length can cover parts of the machine conveniently. Fast beam loss event can be detected with more accurate position. In this paper, the design and result of the optical fiber based beam loss monitor system at SPS machine are discussed. The system will be a prototype for the new 3 GeV machine SPS-II., Proceedings of the 13th International Particle Accelerator Conference, IPAC2022, Bangkok, Thailand

Upon its completion, Siam Photon Source II (SPS-II) will be the first 4th generation synchrotron light source in Southeast Asia. The 3.0 GeV, 327.5 m storage ring based on the Double-Triple Bend Achromat lattice will have the natural emittance of 0.97 nm·rad. The storage ring includes 14 long and 14 short straight sections for insertion devices and machine subsys-tems. The beam injection will be performed by a 150 MeV linear accelerator and a full-energy concentric booster synchrotron sharing the same tunnel with the storage ring. In the first phase, there will be 7 insertion devices and 7 associated beamlines with the end sta-tions for different techniques utilizing synchrotron radiation from 80 eV to 60 keV. High-energy and high-brightness radiation generated by the new light source will serve as one of the most powerful analytical tools in the region for advanced science and technology research., Proceedings of the 13th International Particle Accelerator Conference, IPAC2022, Bangkok, Thailand

A new insertion device, Superconducting Multipole Wiggler (SMPW) with the peak field strength of 3.5 T, was installed in the storage ring of Siam Photon Source as a radiation source for a new hard X-ray beamline. Cool-down process, as well as magnet training, was performed with careful tuning of liquid helium filling procedure for efficient management of liquid helium supply. The filling procedure was also optimized for safe operation of the magnet. The SMPW commission-ing was successfully carried out with electron beam and the effect of SMPW on electron beam dynamics was observed. It can be minimized using quadrupole magnets and horizontal/vertical correctors., Proceedings of the 12th International Particle Accelerator Conference, IPAC2021, Campinas, SP, Brazil

A project on a 3.0 GeV Siam Photon Source II (SPS-II) has been started. The storage ring of SPS-II was designed to obtain an electron beam with a low-emittance below 1 nm-rad. The SPS-II injector mainly consists of a 150 MeV linac and a full-energy booster synchrotron. The booster synchrotron will be installed in the same tunnel as the storage ring, with a total circumference of 304.829 meters. The proposed lattice of the booster contains 40 modified FODO cells with combined function magnets. This lattice achieves a small beam emittance less than 10 nm-rad at 3 GeV, which can provide a high injection efficiency for top-up operation. The conceptual design for SPS-II booster synchrotron is presented in this work., Proceedings of the 12th International Particle Accelerator Conference, IPAC2021, Campinas, SP, Brazil

The new light source facility in Thailand, SPS-II, is a ring-based 3 GeV light source with a circumference of approximately 330 m. The target stored beam current is 300 mA with an emittance of below 1.0 nm rad. The injector has been changed from a full energy linac to a booster injector with 150 MeV linac. The main RF frequency has been reconsidered to a low-frequency range at 119 MHz. Low frequency is chosen with the benefit of low RF voltage for a high RF acceptance together with experience with the present ring RF system of 118 MHz. Details of RF frequency consideration will be discussed. The requirements and details of the RF systems in the booster ring and the storage ring will be presented., Proceedings of the 12th International Particle Accelerator Conference, IPAC2021, Campinas, SP, Brazil

The new Thailand synchrotron light source, Siam Photon Source II (SPS-II), has been designed based on a 3 GeV storage ring with a Double-Triple Bend Achromat (DTBA) lattice and a full energy injector linac. The linac consists of an S-band photocathode RF gun, C-band accelerating structures and two magnetic chicanes. In addition to its main function as the storage ring injector, the linac is capable of producing sub-picosecond electron bunches for additional short-pulse beamlines at the end of the linac. The linac also has a potential to become a driver of a soft X-ray Free Electron Laser (FEL) operating adjacent to the storage ring. In this paper, start-to-end simulations of the full energy linac are presented. Optimization was performed in order to fulfil requirements for both storage ring injection and short pulse generation., Proceedings of the 10th Int. Particle Accelerator Conf., IPAC2019, Melbourne, Australia

The new light source facility in Thailand will be a ring-based light source with the circumference of approximately 300m and an electron energy of 3GeV. The target beam emittance is below 1.0 nm·rad with a maximum beam current of 300mA. The injector utilizes a full energy C-band linac with a photocathode RF electron gun. The storage ring RF system is based on a 500MHz frequency. The EU-HOM damped cavity and the new SPring-8 design TM020 cavity is the choice of the storage ring cavity. The RF power unit for storage ring can either be a high-power klystron feeding all RF cavities or a combination of low power IOTs or solid-state amplifiers feeding each cavity. The high gradient C-band structure is considered as the main accelerating structure for linac. The RF power system for linac will base on klystron and a modular modulator. Details of RF systems options for this new light source project will be presented., Proceedings of the 9th Int. Particle Accelerator Conf., IPAC2018, Vancouver, BC, Canada

In recent years the beam diagnostics and instrumenta-tion of Siam Photon Source (SPS), Thailand synchro-tron radiation facility, have been significantly improved for both the booster synchrotron and the 1.2 GeV stor-age ring. Additional diagnostics have been designed, fabricated, and installed, and the existing systems have been upgraded. This paper describes the current status of the beam diagnostics at SPS, as well as their respec-tive performances. These systems include beam posi-tion monitors (BPMs), a diagnostics beamline, beam loss monitors (BLMs), real-time tune measurement setups, and others. Apart from the instrument hardware, the acquisition electronics along with the processing software have been improved as well. The details of these upgrades are reported herewith., Proceedings of the 5th Int. Beam Instrumentation Conf., IBIC2016, Barcelona, Spain

Siam Photon Source (SPS) in Thailand has been operating and providing synchrotron radiation to users for more than a decade, leading to growing user community in South East Asia region. This gives rise to the possibility of constructing a new 3 GeV light source which could provide synchrotron light with higher photon energy and higher brilliance than the existing 1.2 GeV machine. Hybrid multi-bend achromat (HMBA) lattice design providing small natural beam emittance is a promising choice. In this paper, the Double-Triple Bend Achromat (DTBA) design with extra straight section scaled from Diamond Light Source upgrade lattice [ref.] is presented. Lattice optimisation with simplified magnet specifications still allows natural emittance of about 900 pm'rad for a 321.3 m circumference ring with sufficient dynamic aperture., Proceedings of the 8th Int. Particle Accelerator Conf., IPAC2017, Copenhagen, Denmark

Pulsed multipole magnet (PM) has zero magnetic field at the centre, therefore it introduces no perturbation to the stored beam. It has been demonstrated that this injection scheme is able to minimise the oscillation of the stored beam, and thus make it suitable for top-up operation. To investigate the suitability of employing this injection method at Siam Photon Source, PM was modelled and optimised for best performance using particle tracking based method. This work presents injection optimisation process with PM considering various constraints such as position of injected beam, injection conditions, and effects of installed IDs., Proceedings of the 8th Int. Particle Accelerator Conf., IPAC2017, Copenhagen, Denmark

Siam Photon Source, the Thailand synchrotron light source, has received several upgrades in recent years. Most important of which are the improvement of the positional stability of the stored electron beam, and the installation of 2 IDs, i.e. a 2.2 T hybrid multipole wiggler and a 6.5 T superconducting wavelength shifter, to extend the available SR spectrum into hard x-ray region. The beam stability improvement was achieved through several activities, including improving the BPM system, upgrading the existing corrector power supplies, and implementing global orbit feedback. The two new IDs provide higher-intensity and higher-energy (up to 25 keV) synchrotron light, which will be utilized for MX, high-energy SAXS, WAXS, XAS, and microtomography. Ongoing machine upgrades include increasing the energy of the booster and transport line to 1.2 GeV for full-energy injection and eventual top-up operation. Utilization of the electron beam is also being explored. A beam test facility, which extracts electron beam in the booster for characterizing high-energy particle sensors, as well as calibrating other beam diagnostic instruments, has been constructed and is now in operation., Proceedings of the 8th Int. Particle Accelerator Conf., IPAC2017, Copenhagen, Denmark

Optimisation of a particle accelerator with very limited diagnostic system is proved to be very challenging and complicated. Theoretical calculation and perfect machine model never guarantee the best solution in the actual machine. In this work, optimisation of injection system from Low energy Beam Transport line (LBT) to Siam Photon Source (SPS) storage ring and reduction of beam coupling employing Robust Conjugate Direction Search (RCDS) algorithm are demonstrated. New record improvement on injection efficiency and better coupling control will be presented., Proceedings of the 8th Int. Particle Accelerator Conf., IPAC2017, Copenhagen, Denmark

Limitation of beam lifetime was systematically investigated and studied for Siam Photon Source (SPS) storage ring. The objective was to identify the main cause of the observed reduction of beam lifetime. The simulations of momentum acceptance and Touschek lifetime were performed, incorporating non-linear effects generated by the installed high-field insertion devices. The Touschek lifetime was measured as a function of RF voltage and compared with the values obtained from simulation. The measurements were performed for a variety of different operation conditions of the insertion devices and different chromaticities., Proceedings of the 8th Int. Particle Accelerator Conf., IPAC2017, Copenhagen, Denmark

The Diamond storage ring has been modified by replacing one of the existing double bend achromat (DBA) cells with a double-DBA (DDBA) cell*. This change represents the largest modification to the storage ring since it was first commissioned in 2006, and was installed and fully commissioned during a single 8 week shutdown in autumn 2016. In view of this tight schedule, the planned commissioning steps and all high-level software needed to be developed and thoroughly tested in advance. Electron beam commissioning occupied the final 2 weeks of the shutdown, during which the injected electrons were captured and accumulated, the correct linear lattice was established, the nonlinear beam dynamics were studied, IDs were closed and the target 300 mA was achieved. This paper presents an overview of these activities., Proceedings of the 8th Int. Particle Accelerator Conf., IPAC2017, Copenhagen, Denmark

International audience; The Double Triple Bend Achromat (DTBA) is a newly designed cell for a next generation 3 GeV synchrotron light source. DTBA is inspired by the Double-Double Bend Achromat (DDBA) cell designed for Diamond and originates from a modification of the ESRF HMBA 6 GeV cell, combining in this way the best characteristics of each lattice. The lattice achieves a natural emittance as low as 131 pm, together with a sufficient Dynamic Aperture (DA) for injection and lifetime. Two cells are designed with different end-drift lengths providing two different Long Straight Sections (LSS) for insertion devices, 5 and 7.5 m long, in addition to a new middle-straight section of 3 m. The characteristics of the lattice together with the results on emittance, DA and Touschek lifetime are presented after extensive linear and non-linear optimisations, with and without the presence of errors and corrections.

Investigations are underway for the possible use of an achromat to install a short multipole wiggler by removing a chromatic sextupole in cell-11 of the storage ring. The effect on emittance and energy spread are found to be small, however the impact on lifetime and injection are very significant if the chromaticity is corrected normally (globally). The MOGA genetic algorithm is used to optimize the lifetime and injection efficiency in this case. We used local mirror chromatic sextupole and other chromatic sextupole family for chromaticity correction in which case the genetic algorithm found solution that restores lifetime and injection efficiency. In this paper the results of MOGA simulations using various schemes for chromaticity correction and test results in presently operational optics will be discussed., Proceedings of the 7th Int. Particle Accelerator Conf., IPAC2016, Busan, Korea

Starting from the concepts of the Hybrid Multi Bend Achromat (HMBA) lattice developed at ESRF and of the Double-Double Bend Achromat (DDBA) lattice developed at Diamond, we present a new cell that includes all the advantages of the two designs. The resulting Double Triple Bend Achromat (DTBA) cell allows for a natural horizontal emittance of less than 100 pm with a large dynamic aperture and lifetime. It includes two straight sections, for insertion devices, five and three meters long. The lattice is consistent with the engineering design developed for the ESRF-EBS lattice and the layout and user requirements of Diamond. The characteristics of the cell are presented together with the results of the optimisation process., Proceedings of the 7th Int. Particle Accelerator Conf., IPAC2016, Busan, Korea

To generate intense and high energy synchrotron radiation at the Siam Photon Source (SPS) 1.2 GeV storage ring, two insertion devices (IDs), namely, a 2.2 T hybrid multipole wiggler (MPW) and a 6.5 T superconducting wavelength shifter (SWLS), have been installed and operated since 2013. The angular kicks due to the nonlinear effects generated by the IDs represented by kick maps were used in our analysis. The optics distortion was compared to the ones obtained from calculation using hard-edge model and measurement results. In order to investigate the effects of IDs on the beam dynamics, Frequency Map Analysis (FMA) was employed. The effects of the IDs and their compensation are presented herewith., Proceedings of the 7th Int. Particle Accelerator Conf., IPAC2016, Busan, Korea

Nonlinear effects of insertion devices were studied for the Siam Photon Source (SPS) storage ring. Despite the fact that shimming technique was used to minimize the nonlinear components of magnetic field integral arising from random errors, the nonlinear dynamics effects still remain. It was found that calculated dynamic field integrals are largest in the 2.2 T Hybrid Multipole Wiggler (MPW). Dynamics effects of insertion devices are attributed to the wiggling trajectory of electron in the region of magnetic field roll-off due to finite pole width. For better and more effective operation of the SPS storage ring, multipole components of the dynamic field integral in the MPW have to be further reduced., Proceedings of the 7th Int. Particle Accelerator Conf., IPAC2016, Busan, Korea

The DDBA lattice upgrade for Diamond presents challenging requirements on the magnet system in order to satisfy the tight constraints on the beam optics. Advanced, combined function gradient dipoles and high gradient quadrupoles are needed. We present the tolerance specification, the design solutions and the measurement and alignment strategies., Proceedings of the 5th Int. Particle Accelerator Conf., IPAC2014, Dresden, Germany

The design and optimisation of the new DDBA lattice for Diamond has been performed taking fully into account, from the early stages, the geometry and the engineering integration constraints. In this paper we review the evolution of the DDBA cell, the rationale for its modification and the optimisation strategy used., Proceedings of the 5th Int. Particle Accelerator Conf., IPAC2014, Dresden, Germany

The concept of converting individual cells of the Diamond Double Bend Achromat (DBA) lattice into a modified 4-bend achromat with a new straight section for insertion devices (IDs) in the middle of the arc, grew out of earlier studies of low emittance MBA lattices*, and was motivated by the need for additional ID straight sections, since all of the 22 ID straight sections in the Diamond storage ring are either occupied or have been allocated to future beamlines. Such a modification effectively replaces each DBA cell with two new DBA cells, hence the term Double-DBA or DDBA has come to be used for the project. Since the tangent point for bending magnet beamlines lies close to the start of the second dipole in the original DBA, this allows unused exit ports and spaces on the experimental hall which are available for future bending magnet beamlines to be used for higher performance ID beamlines. In this report we present an overview of the status of the project, the various accelerator physics and engineering studies that have been carried out, and plans for the implementation of one or two DDBA cells in Diamond., Proceedings of the 5th Int. Particle Accelerator Conf., IPAC2014, Dresden, Germany

The Double Triple Bend Achromat (DTBA) is a newly designed cell for a next generation 3 GeV synchrotron light source. DTBA is inspired by the Double-Double Bend Achromat (DDBA) cell designed for Diamond and originates from a modification of the ESRF HMBA 6 GeV cell, combining in this way the best characteristics of each lattice. The lattice achieves a natural emittance as low as 131 pm, together with a sufficient Dynamic Aperture (DA) for injection and lifetime. Two cells are designed with different end-drift lengths providing two different Long Straight Sections (LSS) for insertion devices, 5 and 7.5 m long, in addition to a new middle-straight section of 3 m. The characteristics of the lattice together with the results on emittance, DA and Touschek lifetime are presented after extensive linear and non-linear optimisations, with and without the presence of errors and corrections., Proceedings of the North American Particle Accelerator Conf., NAPAC2016, Chicago, IL, USA