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The Taiwan Photon Source (TPS) is capable of operat-ing in multi-bunch and single-bunch mode. To operate in a hybrid mode as requested by users, we developed a lattice with chromaticities of 0.8/2 (x/y) to provide higher single bunch currents. Beam dynamics simulations and lattice characterizations including dynamic aperture, frequency map analysis, tune shift with energy, tune shift with amplitude, and betatron coupling will be discussed in this report., Proceedings of the 10th Int. Particle Accelerator Conf., IPAC2019, Melbourne, Australia

Development of cryogenic permanent magnet un-dulators (CPMUs) is the most recent activity for Phase-II beamlines at the Taiwan Photon Source. A hybrid-type CPMU with a period length of 15 mm, based on PrFeB permanent-magnet materials, is under construc-tion. A maximum effective magnetic field of 1.33 T at a gap of 4 mm is obtained at 80 K., Proceedings of the 10th Int. Particle Accelerator Conf., IPAC2019, Melbourne, Australia

A superconducting multipole wiggler (SMPW) was fabricated at the National Synchrotron Radiation Research Center (NSRRC) and was installed in the Synchrotron Light Research Institute (SLRI). A 3.5 T field strength could be generated by the NbTi coils and the magnetic arrays are immersed in a liquid helium (LHe) bath. A removable mapping chamber, made from thin stainless steel sheets, was developed to allow field mapping in the narrow aperture of the SMPW. The mapping chamber provides a room temperature environment for the magnetic field mapping and enables an easier field scan in the cryostat. The design for the mapping chamber includes a blockage of heat transfer from room temperature to the LHe bath and is strong enough to resist deformations during evacuation. The mechanical design, strain simulation, thermal simulation, dummy test and measurement results with the mapping chamber will be discussed in this paper., Proceedings of the 10th Int. Particle Accelerator Conf., IPAC2019, Melbourne, Australia

We present a TPS upgrade option with the hybrid 7BA (H7BA) lattice. We also derive a simple formula on optimal dipole angle distribution among H7BA dipoles. The agreement is satisfactory. We also report preliminary results on the dynamic aperture (DA) optimization. Possible improvement on H7BA lattice is outlined., Proceedings of the 10th Int. Particle Accelerator Conf., IPAC2019, Melbourne, Australia

We have developed a beam-based alignment procedure for small gap IVUs (In-vacuum undulators) at TPS, which allow us to measure the field center and mechanical canter of IVUs with 0.1 mm accuracy. The measurement method and results are presented in this paper., Proceedings of the 9th Int. Particle Accelerator Conf., IPAC2018, Vancouver, BC, Canada

A PrFeB-based cryogenic permanent magnet undu-lator (CPMU) is under construction at the Taiwan Photon Source (TPS) to generate brilliant X-rays. When magnets are cooled to 77 K, a CPMU with a period length of 15 mm can generate an effective magnetic field of 1.32 T in a gap of 4 mm. A main feature of the TPS CPMU is its low-intrinsic-phase errors by the installation of force-compensation modules on the out-of-vacuum girders in a four-support-points configuration. Moreover, adjusting the spring settings one can obtain very low undulator phase errors. In this paper, a mechanical frame design for the TPS-CPMU with force-compensating spring modules will be discussed. Observations of deformation effects of the out-of-vacuum girders on the CPMU will be presented., Proceedings of the Mechanical Eng.~Design of Synchrotron Radiation Equipment and Instrumentation, MEDSI2018, Paris, France

Short period in-vacuum, permanent magnet undulators operating at cryogenic temperatures are being developed worldwide to serve as brilliant and coherent light sources for medium energy storage rings. A hybrid cryogenic permanent magnet undulator (CU) with PrFeB magnets has now been designed and constructed at NSRRC [1]. To characterize the performance and to determine magnetic field errors after cool down poses some technical chal-lenges compared to room temperature undulators. A new system combining a Hall probe and a stretched wire has been designed to measure the field integrals, trajectory, phase errors, and K value under low temperature and vacuum conditions. Field measurements in this cryogenic undulator will be performed around 77 K as well as at room temperature, making temperature dependent calibra-tion of the Hall probes necessary. The main features and improvement of the measurement and calibration system are presented., Proceedings of the 8th Int. Particle Accelerator Conf., IPAC2017, Copenhagen, Denmark

Development of a cryogenic permanent magnet undu-lator (CPMU) at the Taiwan Photon Source (TPS) is the most recent activity toward a new light source for the Phase-II beamlines. A hybrid-type CPMU with a period length of 15 mm is under construction with PrFeB permanent-magnet materials. A maximum effective magnetic field of 1.77 T at a gap of 3 mm is expected when the magnets (PMs) are cooled down around 77 K. The features desired for the TPS CPMU are low-intrinsic-phase-error characteristics and high thermal budget for various kinds of heat loads. The design of the TPS CPMU is discussed in this paper., Proceedings of the 8th Int. Particle Accelerator Conf., IPAC2017, Copenhagen, Denmark

Cryogenic permanent-magnet undulators (CU) have currently become the most important scheme serving as sources of hard X-rays in medium-energy facilities worldwide. One such set (length 2 m, period length 15 mm) is under development for Taiwan Photon Source (TPS). To obtain a magnetic-field distribution of the cryogenic undulator after it is cooled to an operating target temperature below 80 K, a device of hybrid type combining a Hall probe and stretched-wire method has been designed and developed, to perform the field measurement at low temperature and in an ultra-high vacuum environment. The Hall probe is used to measure the field on axis in the transverse and vertical directions; the stretched wire is utilized to measure the field integral in the vertical and horizontal directions in the horizontal plane. Unlike a conventional field-measurement system in air, this innovative system must be located in an ultra-high vacuum environment with limited clearance. This paper describes mainly the entire system, including kernel components, control systems and preliminary test results in detail., Proceedings of the 9th Edition of the Mechanical Engineering Design of Synchrotron Radiation Equipment and Instrumentation Conference, MEDSI2016, Barcelona, Spain

Liquid helium for transferring cooling power from the cryogenic plant to the magnets and SRF cavities had been widely applied on the advanced large superconducting particle accelerators. For requirements of high stable and reliable operation, many efforts have been put into the improvement and modification of the cryogenic system. However, personnel safety is another critical issue of the cryogenic system. Once large liquid helium was released on the atmospheric tunnel, the volume of helium will expand several hundred times and cause oxygen deficiency in short time due to sudden change of helium density. In this study, we applied numerical simulation to analyze helium discharge through a SRF cavity in the TPS tunnel., Proceedings of the 8th Int. Particle Accelerator Conf., IPAC2017, Copenhagen, Denmark

The storage ring of Taiwan Photon Source (TPS) has eighteen short straight sections (length 7 m) and six long straight sections (length 12 m). In phase I, three elliptically polarized undulators of type APPLE II and seven in-vacuum undulators, which included four in-vacuum undulators and two elliptically polarized undulators in three double mini-βy sections, were installed. Commissioning of the insertion devices began in 2015 November. The influence of insertion devices on the electron beam and the results after compensation are presented. Problems during the commissioning induced by the electron beam and by radiation, and their solutions, are also explained. For insertion devices in phase II and for devices developed in TPS, the preliminary designs are presented herein, to cover from the VUV to the hard X-ray region., Proceedings of the 7th Int. Particle Accelerator Conf., IPAC2016, Busan, Korea

Taiwan Photon Source (TPS) is a 3-GeV light source. The full current of the storage beam and commissioning of insertion devices are still in progress. An improved injection between the booster ring (BR) and the storage ring (SR) was implemented to increase the efficiency of injection and the reliability of the electrical parts. A DC septum (length 0.8 m) was replaced with an AC septum (length 1 m, type C) to decrease the leakage field and to relax the loading of the power supply. Mapping the field with mu-metal shielding was also implemented to diminish the leakage field from the AC septum. The lattice of the transfer line between the booster ring and the storage ring, BTS, was also rearranged to meet the new injection requirements. The performance of the AC septum with mu-metal shielding and the upgrade of the BTS lattice are discussed in this paper., Proceedings of the 7th Int. Particle Accelerator Conf., IPAC2016, Busan, Korea

The Taiwan Photon Source (TPS) is a low-emittance 3-GeV light source at Natioal Synchrotron Radiation Research Center, next to the Taiwan Light source (1.5 GeV). On March 26, 2015, the TPS storage ring with two 5-cell PETRA cavities has successfully operated in 100 mA in top-up mode without the installation of insertion devices (IDs). To reach the design goal of 500 mA, the machine was shut down for 5 months to replace PETRA cavitites with superconducting RF (SRF) cavities and to install 10 IDs: 7 in-vacuum undulators (IU) and 3 elliptically polarized undulators (EPU). The commissioning of TPS storage ring with SRF cavities and IDs began in Sep. 2015. In this paper, we present our results and proceedures of ID commissioning., Proceedings of the 7th Int. Particle Accelerator Conf., IPAC2016, Busan, Korea

Taiwan Photon Source (TPS) is a synchrotron radia-tion facility with electron energy 3 GeV that was commissioned in 2015. Taiwan Light Source (TLS) with electron energy 1.5 GeV concurrently provides user time. Three beam lines of TLS supply photons of energy 6-18 keV for user experiments; these beam lines are served with an in-achromatic superconduct-ing wiggler (IASW, 3.1 T). This superconducting inser-tion device has the disadvantages of complicated maintenance and operation. A traditional multipole wiggler (MPW) magnet of hybrid type is hence planned to be installed in TPS to cover the range of photon energy of IASW for user experiments. For the design of the magnetic circuit, the side block and the extreme block are arranged surrounding a Permendur Vanadium cobalt steel pole that enhances the field strength and good field region of a MPW magnet. The dynamic integral field and the demagnetizing field of MPW magnet were estimated. The optimization of the pole dimensions and photon characteristics were simu-lated and are discussed in this work., Proceedings of the 7th Int. Particle Accelerator Conf., IPAC2016, Busan, Korea

An in-vacuum undulator (IVU) opens the utilization of high-brilliance X-rays in the medium energy storage rings. The development of a short-period undulator with low phase error becomes important to bring X-ray into a new unprecedented brilliant light source in an ultimate storage ring (USR). NdFeB or PrFeB cryogenic permanent magnet undulators (CPMUs) with a short period have been developed worldwide to obtain high brilliance of undulator radiation. A CPMU has high resistance against beam-induced heat load and allow to operate at a narrow gap. In a low emittance or ultimate storage ring, not only the performance of an undulator but the choice of the lattice functions is very important to obtain high bril-liance of synchrotron radiation. The optimum betatron functions and zero dispersion function shall be given for a straight section at IVU/CPMUs. In this paper, the relevant factors and design issues for IVU/CPMU will be discussed. Many technological challenges of a short-period undulator associated with beam induced-heat load, phase errors, and the deformation of in-vacuum girders will also be presented herein., Proceedings of the 7th Int. Particle Accelerator Conf., IPAC2016, Busan, Korea

Two collinear in-vacuum undulators (IU22) are adopted for light source of X-ray coherence beamline in Taiwan photon source. Each undulator is 3 meter and the drift space between two undulator is 3.991m. The synchrotron radiation is propagating in the longitudinal direction and will result in a serious heat load problem for undualtor downstream. The magnet array of undualtor downstream will received the synchrotron radiation of 142W from upstream bending magnet and undualtor. Heat load is a critical challenge for in-vacuum undulator in double mini-beta Y lattice and therefore details analysis in this paper., Proceedings of the 5th Int. Particle Accelerator Conf., IPAC2014, Dresden, Germany

A cryogenic undulator with a permanent magnet (CPMU) is an important insertion device now under construction at NSRRC. For an undulator of this kind, the distribution of the magnetic field must be measured along the axis; the phase error, trajectory and photon flux must be calculated after the magnetic arrays are installed in the vacuum chamber and cooled to cryogenic temperature. We developed a Hall-probe system to measure the magnetic field in an evacuated environment; this system uses lasers and stages to monitor and to correct dynamically the positions of the Hall probe. All components installed inside the vacuum chamber are compatible with an environment of high vacuum and low temperature. The details of the design and completed fabrication are presented in this paper., Proceedings of the 5th Int. Particle Accelerator Conf., IPAC2014, Dresden, Germany

Pulsed magnet system of Taiwan Photon source(TPS) requires a very low stray field to avoid parasitic magnetic field into the stored beam. The stray field from storage ring(SR) injection septum is required to be less than 0.2 Gauss. The most common method to protect parasitic magnetic field is to use high permeability and conductivity material, such as a Mu-metal. A 1.2 ms half-sine wave pulse of up to 8280A current peak are supply to a septum and would result in eddy current loss in magnet and conductor current diffusion during the rapid charging on magnet. Moreover, competition between eddy current loss and magnetic permeability would lead to a complex phenomena inside the mumetal shielding cabinet and shielding performance. In this study, the magnetic shielding performance of a shielding cabinet was examined in different shielding cabinet geometry and thickness. The results were calculated in Opera software and show that there is a significant suppression of SR septum stray field when round shielding cabinet is in use., Proceedings of the 1st International Particle Accelerator Conference, IPAC2010, Kyoto, Japan

Taiwan Photon Source (TPS) is a new third generation synchrotron storage ring with energy 3 GeV, which consists of 24 double-bend cells and its circumference is 518.4 m. Various accelerator lattice magnets which consist of 48 bending magnets, 240 quadrupoles and 168 multifunction sextupole magnets. All magnets pole profiles, edge shim and magnet end chamfer were designed in TOSCA and RADIA magnetic computation code. In order to verify the magnetic field quality of computation code, prototype magnets have been manufactured in this year. Two measurement systems, hall probe and rotating coils, were used for magnetic field mapping. This paper presents magnetic field mapping results of prototype magnets and compared with original magnetic circuit designs., Proceedings of the 1st International Particle Accelerator Conference, IPAC2010, Kyoto, Japan

An elliptically polarized undulator of length 3.5 m and period length 48 mm (EPU48) is designed to fulfil experiments on spin-polarized PES and inelastic scattering at the Taiwan Photon Source (TPS). EPU48 would be used to produce variously polarized light in the soft X-ray spectral domain 0.4-1.5 keV. To achieve efficient mechanical performance and a high quality of photon source, a new manufacturing method by casting is adopted to fabricate a key component of the carriage of the undulator at National Synchrotron Radiation Research Center (NSRRC). We expect this approach to bestow advantages of decreased assembly error, increased rigidity and highly precise properties. Here we describe details of the design of the magnetic circuit and the mechanical design of the EPU48 based on this new concept of engineering construction., Proceedings of the 1st International Particle Accelerator Conference, IPAC2010, Kyoto, Japan

Transonic shock wave/boundary layer interaction over a wall-mounted bump was investigated with specific focus on shock wave unsteadiness and identification of its source. A large separation bubble resulted of an interaction driven by a flow characterized by a peak Mach number of 1.365. Overall this particular type of transonic unsteadiness is characterized with low amplitude and relatively high frequency motion. Low frequency shock unsteadiness was optically estimated and matched spectral content of wall fluctuating pressure. A strong correlation between separation onset and reattachment zones suggested a model of bubble expansion/contraction at the reattachment point where upstream-traveling pressure waves are generated and cause the shock wave excursions.