Browsing by Author "Hwang, C. S."

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A gasket-type standard leak element using femtosecond laser micromachining
(2020-10-01)
Chan, C. K.
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Tu, C. Y.
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Yeh, S. D.
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Chang, C. C.
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Lin, T. C.
A gasket-type standard leak element with a microfluidic channel was developed and measured. The microfluidic channel with a diameter of several micrometers and a length of one hundred micrometers was fabricated by using femtosecond laser micromachining. The conductances (<1 x 10(-6) L s(-1)) of the micmfluidic channel for various non-condensable gases - H-2, He, CH4, N-2 and CO2 were determined by a measuring system based on conductance modulation (CM) method. The experimental results show that the flow characteristics of our devices exhibit molecular flow at a pressure up to 100 mbar and the conductance values of H-2, He, CH4, N-2 and CO2 are inversely proportional to the square root of their molecular mass.
A Superconducting Magnetization System With Hybrid Superconducting Wire for the Study and Application of Superconductivity
(2012-06-01)
Chen, S. D.
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Yu, Y. T.
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Jan, J. C.
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Lin, F. Y.
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Hwang, C. S.
For the study of high-temperature superconductors and for the application of superconductivity, a superconducting high-field magnetization system with a hybrid superconducting coil was designed. This coil is composed of superconducting wires of three kinds-HTS YBCO 2G-wire, high-field and low-field NbTi wires. Three principal purposes of building this system are to inspect the characteristics of disk-shape bulk YBCO, to develop a HTS-bulk undulator, and to magnetize a portable HTS-bulk high-field magnet for application to a resonant X-ray scattering experiment. With four steps of temperature decrease, a two-stage GM-type cryocooler and liquid nitrogen provide cooling for the magnetization system. The hybrid superconducting coil, two cryogenic systems for the magnetization system and the portable HTS-bulk magnet, and the control and monitor systems that were designed are discussed.
An Algorithm for the Optimization of Insertion Devices to Increase Useful Flux and to Decrease Useless Radiation Power
(2010)
Chen, S. D.
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Hwang, C. S.
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Liang, K. S.
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電子物理學系
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Department of Electrophysics
A continuous spectrum of synchrotron radiation in the hard x-ray region, 5-20 keV, is necessary for the special demand of users, but the high radiation power in that continuous spectrum adversely affects the design of optical components in the beam line. A compromise between photon flux and radiation power of insertion devices should hence be considered. An algorithm and code for spectrum optimization was hence developed using program Mathematica. A wiggler-like undulator with a continuous spectrum was investigated with this code. An optimization algorithm for continuous spectra in the energy range 5-20 keV is presented, and features of the wiggler-like undulator with a continuous spectrum are discussed herein.
Decreasing the Emittance Using a Multi-period Robinson Wigglers in TPS
(2016)
Huamg, C. W.
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Hwang, C. S.
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Lee, S. Y.
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電子物理學系
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Department of Electrophysics
The Taiwan Photon Source (TPS) has been successfully commissioned. However, the minimum emittance in the TPS lattice is 1.6 nm rad. In the existing TPS storage ring lattice, it is imperative to reduce the emittance to below 1 nm rad. Therefore, a feasibility study for reducing the effective emittance of the TPS storage ring by using a Robinson wiggler was launched; the reduction is necessary to enhance the photon brilliance. In this study, a permanent-magnet multiperiod Robinson wiggler (MRW) was developed for use instead of the single-period Robinson wiggler. In general, the quadruple field of a combined function magnet in the storage ring is approximately few tesla per meter. According to beam dynamic analysis, we found that it is necessary to adopt a high gradient (40 T/m) combined-function MRW magnet to reduce the emittance effectively. Therefore, a high gradient field strength is required in the combined function MRW magnet. In this study, the quadrupole field strength of the MRW magnet was allowed to be approximately 40T/m at a magnet gap of 20 mm. The period length of the MRW magnet was 300 mm and the period number was 16. The of MRWs is discussed in regard to the possibility of increasing the photon brilliance from IU22.
Design Improvement of a Staggered YBCO Undulator
(2018-04-01)
Chen, S. D.
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Chiang, C. A.
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Yang, C. M.
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Yang, C. K.
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Luo, H. W.
A strong field and short period undulator can be a desirable light source device in a storage ring or a free-electron laser. Bulk YBCO can be used to construct a high-temperature-superconducting undulator in a staggered array structure. The YBCO material in form of 32 mm diameter and 2.5 mm thick was used to assemble a staggered magnet array. The period length is 5 mm and the magnet gap is 4 mm. To estimate the strength of a sinusoidal field and to optimize the end-pole design to minimize the first (i.e., electron angle) and second field integral (electron position), an energy-minimization method (EM-method) based on Bean's model to simulate the field trapped in the HTS-Block is introduced. In this paper, we focus on promoting the practical value of the EM-method simulation. Combining the experimental experience of a YBCO staggered undulator and the simulation experience based on the EM-method, we address some issues to enhance the efficacy of this undulator design.
Design of a HTS Magnet for Application to Resonant X-Ray Scattering
(2011-06-01)
Chen, S. D.
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Yu, Y. T.
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Huang, Z. W.
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Jan, J. C.
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Hwang, C. S.
In material research, the characteristics of novel materials vary greatly with the environment. A magnet with a strong field will be developed for an experimental station for resonant X-ray scattering to investigate the magnetic properties of materials. This magnet will be developed with high-temperature superconductor (HTS) bulk YBa(2)Cu(3)O(7) and magnetized with a HTS coil magnet wound with 2G HTS wire. HTS (RE) BCO will be selected to construct the coil of this magnet. Both the bulk and coil magnets will be assembled on the same movable system. The bulk HTS magnet will provide flux density greater than 4 T with a gap 34 mm that can accommodate the sample holder of the experimental station. The bulk magnet will be cooled with cryocoolers to 29 K and the coil magnet to 4.2 K; the coil magnet is separable from the bulk magnet after the field is trapped. We describe the concept of the magnetic-field calculation, the overall design of these magnets, and the cooling algorithm for the bulk HTS magnet system.
Design of a Hybrid Multiperiod Robinson Wiggler for TPS Light Source
(2016-06)
Huang, C. W.
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Chung, T. Y.
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Chang, C. H.
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Hwang, C. S.
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電子物理學系
A Robinson wiggler is designed to decrease the emittance within 1 nm . rad for Taiwan Photon Source. According to an analysis of the beam dynamics, decreasing the emittance with a multiperiod Robinson wiggler is more efficient than a single-period traditional Robinson wiggler. This wiggler consists of a dipole field and a strong gradient field, which creates a strong dynamic field integral multipole error. To enhance the gradient field and to have also a small dynamic field integral multipole error, a compensated side-pole design and an edge-pole shape in each pole are proposed in this paper. After optimization of the magnet, the dipole and gradient fields are 0.82 T and -37 T/m, respectively. The concept of the design of the magnetic circuit and the results of an analysis of the magnetic field are discussed herein.
Development of a superconducting elliptically polarized undulator
(2010)
Chen, S. D.
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Jan, J. C.
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Hwang, C. S.
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Liang, K. S.
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電子物理學系
A superconducting, elliptically polarized undulator (SEPU24) with a period of length 24 mm was developed to provide first-harmonic photons from a 0.8 GeV storage ring for extreme-ultraviolet (EUV) lithography experiment. In SEPU24, two layers of a magnet array structure - with and without rotated magnet arrays - are combined to generate a helical field that provides radiation with wavelength 13.5 nm in the in-band energy. The arrays of iron and aluminium poles were wound with a racetrack coil vertically as for the magnet pole array. The elliptical field is created when the up and down magnet-pole arrays pass excitation currents in alternate directions. SEPU24 is designed with a magnet of gap 6.8 mm, yielding magnetic flux density B-x=B-z=0.61 T of the helical field. A prototype magnet was fabricated with a diode for quench protection, and assembled in a test dewar to test the magnet performance. A cryogenic Hall-probe system with a precise linear stage was used to measure the distribution of the magnetic field. We describe the design concept and algorithm, the engineering design, the calculation of the magnetic field, the construction and testing of the 10-pole prototype magnet and related issues.
Development trends for insertion devices of future synchrotron light sources
(2011-04-28)
Hwang, C. S.
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Jan, J. C.
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Chang, C. S.
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Chen, S. D.
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Chang, C. H.
The in-vacuum undulator with a permanent magnet at room temperature is a mature technology and is widely used; with a short period length in a medium-energy facility, it can enhance photon brilliance in the hard x-ray region. A cryogenic permanent magnet has been investigated as an in-vacuum undulator; this undulator will become the best prospective device to satisfy the requirements of a photon source with great brilliance in the hard x-ray region. For the further hard x-ray region, a superconducting wiggler can provide great flux with a continuous spectrum, whereas a superconducting undulator will provide great brilliance with a discrete spectrum. High-temperature superconducting wires are highly promising for use in the development of superconducting undulators; unique algorithms for their development with an extremely short period in a small-magnet gap have been devised. Some out-of-vacuum planar undulators with special functions must also be fabricated to enable diverse applications in various light-source facilities. This article describes current and future developments for insertion devices in storage-ring and free-electron-laser facilities and discusses their feasibility for use therein.
Feasibility and Features of a Staggered Undulator Constructed With HTS YBCO Bulks
(2014-06-01)
Chen, S. D.
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Hwang, C. S.
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Yang, C. M.
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Chen, I. G.
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電子物理學系
A staggered undulator with high-temperature superconducting bulks might be a solution to achieve an undulator with an extremely short period for a synchrotron light source. YBCO bulk was thus selected to investigate the feasibility. This bulk (diameter 32 mm, thickness 2.5 mm) was used to build a staggered-magnet array structure and a mock-up staggered undulator of period 5 mm and fixed gap 4 mm was designed for this test. The potential generation of a sinusoidal field was tested in a 3-T magnetization system with field-cooling magnetization (FCM). The practicability of a HI'S undulator is discussed in regard to the possibility of correction of the local field, repetition of field trapping and long-term stability. In addition, a field simulation concept was developed for designing the staggered undulator with YBCO bulks.