Browsing by Author "Hwang, Ching-Shiang"

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A Compact 4.4 Tesla Cryogenic Wavelength Shifter for the Taiwan Photon Source
(2017)
Wang, Chao-Chin
;
Chang, Cheng-Hsiang
;
Hwang, Ching-Shiang
;
Lee, Chih-Hao
;
電子物理學系
The feasibility of a compact 4.4 T in-vacuum cryogenic Pr2Fe14B-based wavelength shifter was studied at the Taiwan Photon Source. The overall dimensions of the magnet array are height 205 mm, length 240 mm, and width 160 mm; the magnet array operates at magnet gap 5 mm. The roll-off of the central field on the transverse axis was designed to be less than 0.1% between +/- 20 mm. The magnitudes of the integral multipole field error and the transverse tune shift as a function of transverse position were optimized to be less than 200 G cm and 4 x 10(-3) between +/- 15 mm. A reverse field occurred so that the Pr-Fe-B bulk became partially demagnetized near 295 K, but it was improved upon chamfering the iron poles near the regions of that reverse field to avoid demagnetization of the Pr-Fe-B bulk.
A Compact 4.4 Tesla Cryogenic Wavelength Shifter for the Taiwan Photon Source
(2017)
Wang, Chao-Chin
;
Chang, Cheng-Hsiang
;
Hwang, Ching-Shiang
;
Lee, Chih-Hao
;
電子物理學系
The feasibility of a compact 4.4 T in-vacuum cryogenic Pr2Fe14B-based wavelength shifter was studied at the Taiwan Photon Source. The overall dimensions of the magnet array are height 205 mm, length 240 mm, and width 160 mm; the magnet array operates at magnet gap 5 mm. The roll-off of the central field on the transverse axis was designed to be less than 0.1% between +/- 20 mm. The magnitudes of the integral multipole field error and the transverse tune shift as a function of transverse position were optimized to be less than 200 G cm and 4 x 10(-3) between +/- 15 mm. A reverse field occurred so that the Pr-Fe-B bulk became partially demagnetized near 295 K, but it was improved upon chamfering the iron poles near the regions of that reverse field to avoid demagnetization of the Pr-Fe-B bulk.
Active and passive compensation of APPLE II-introduced multipole errors through beam-based measurement
(2016-08-01)
Chung, Ting-Yi
;
Huang, Szu-Jung
;
Fu, Huang-Wen
;
Chang, Ho-Ping
;
Chang, Cheng-Hsiang
The effect of an APPLE II-type elliptically polarized undulator (EPU) on the beam dynamics were investigated using active and passive methods. To reduce the tune shift and improve the injection efficiency, dynamic multipole errors were compensated using L-shaped iron shims, which resulted in stable top-up operation for a minimum gap. The skew quadrupole error was compensated using a multipole corrector, which was located downstream of the EPU for minimizing betatron coupling, and it ensured the enhancement of the synchrotron radiation brightness. The investigation methods, a numerical simulation algorithm, a multipole error correction method, and the beam-based measurement results are discussed. (C) 2016 Elsevier B.V. All rights reserved.
Design concept of an electromagnetic undulator to produce arbitrarily polarized light
(2020-06-01)
Chung, Ting-Yi
;
Chen, Sei-Da
;
Jan, Jyh-Chyuan
;
Hwang, Ching-Shiang
;
電子物理學系
An undulator magnet design is described consisting of four electromagnet arrays to produce arbitrarily polarized photon beams including a linear inclined mode. Polarization changes are effected by a current switch rather than mechanical longitudinal translations. The capability of choosing a variety of current excitations in each double coil of the structure can produce any desired polarization mode. This concept exhibits an advantage over mechanical designs especially for superconducting design versions of this undulator. In this paper, we will discuss the magnet structure concept, the current distribution in each double coil and magnetic field features for various polarizing modes. In addition, the concept of current switching will be discussed, which allows to reduce the number of individual current sources from eight to one.
Investigating excitation-dependent and fringe-field effects of electromagnet and permanent-magnet phase shifters for a crossed undulator
(2017-04-01)
Chung, Ting-Yi
;
Yang, Chih-Sheng
;
Chu, Yun-Liang
;
Lin, Fu-Yuan
;
Jan, Jyh-Chyuan
To enhance the flux density or to control polarization, a phase shifter was designed and used to modulate the phase matching between segmented undulators. A larger hysteresis loop causes, however, a repeatability issue in the phase matching; the fringe field of the phase shifter creates an extra magnetic-field error. The design of the phase shifter must therefore minimize the hysteresis loop and fringe field to maintain the phases exact and to ignore the crosstalk effect. Two critical issues are the hysteresis-loop problem and the fringe-field effect, which determine the radiation performance and the stability of the ring. To investigate these issues, a phase shifter was constructed to operate in accordance with electromagnetic- and permanent-type magnets; the results from the field measurements and shims are discussed here. The shimming algorithm and a compact permanent-magnet phase shifter that eliminates the issues are also presented.
Numerical analysis of brilliance and coherent photon flux of segmented undulator radiation based on statistical optics
(2019-01-01)
Luo, Hao-Wen
;
Chung, Ting-Yi
;
Lee, Chih-Hao
;
Hwang, Ching-Shiang
;
電子物理學系
A method based on wave optics together with electron tracking is used to analyze synchrotron radiation from a segmented undulator in a double or multi mini- function lattice storage ring. Radiation brilliance and transverse coherence features are investigated, where the former is calculated with the Wigner distribution function and the latter is evaluated by integrating the photon flux and cross-spectral density to exhibit the coherent flux and overall degree of coherence. To be specific, radiation properties for a single undulator in a typically single mini- function and a tandem undulator in a double mini-(y) lattice are compared in this work. As a result, both, brilliance and coherent flux can be enhanced by a second tandem undulator at the Taiwan Photon Source.