Browsing by Author "Lin, FY"

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Performances and characteristics of a prototype symmetric hybrid adjustable phase undulator
(1997-11-11)
Hwang, CS
;
Chang, CH
;
Fan, TC
;
Lin, FY
;
Wang, C
In this work, we construct and measure a prototype symmetric Hybrid Adjustable Phase Undulator (HAPU) with nine poles to compare phase change and gap change in terms of their features and performances. HAPU can also provide the different characteristics between the pure and hybrid adjustable phase undulator. The HAPU has been installed in the Synchrotron Radiation Research Center (SRRC) storage ring to test the performance of the beam dynamics and photon flux behavior. A three-orthogonal Hall probe and a long-loop-coil measurement system are also implemented to take the field measurements. The multipole field and electron trajectory correction are made by shimming, the magic finger, and the active end pole coil corrector. After the field measurements, the vertical integral strength of HAPU is markedly smaller than that of the Hybrid Adjustable Gap Undulator (HAGU) and confirm that no obvious distinction arises between HAPU and HAGU in terms of the spectrum flux. The electron beam dynamic performance in the storage ring indicates that the vertical tune shift of HAPU is three times smaller than that of HAGU. Meanwhile, the energy dynamic tuning with the digital global feedback turned on, the photon position and flux in the bending chamber beam line is invariant. In addition, the injection efficiency remains unaffected at any phase position and the electron beam lifetime does not change when HAPU is in the dynamic tuning.
Photon spectrum characteristics and magnetic field performance of the prototype hybrid symmetry undulator magnet in SRRC
(1997-10-01)
Hwang, CS
;
Chang, CH
;
Lin, FY
;
Fan, TC
;
Yeh, S
A prototype Halbach hybrid magnet structure undulator with period of 10 cm was used to achieve a high magnetic field. A nearly sinusoidal magnetic field strength of 0.964 Tesla at 24 mm gap was achieved. The magnetic field was also designed and calculated using the magneto-static 3-D code of ''TOSCA''. According to those results, the field uniformity was better than 0.1% in the field rolloff range of x = +/-10 mm at 24 mm gap. The real field profile was measured to find the magnetic field behavior and the photon energy spectrum characteristics. In addition, field distributions obtained from the field measurement and simulation were used to calculate the photon spectrum characteristic. After the multipole and spectrum shimming, the good field region was controlled within 100 G.cm in the range of -2 cm less than or equal to x less than or equal to 2 cm to increase the dynamic aperture. A maximum phase error around 5.5 degrees was achieved and then maintained a high flux in the higher harmonic spectrum. The photon flux intensity is very close to the value of the ideal field simulation, which is about 10(15) photons/sec/100mA/0.1%BW. The energy range of the first harmonic ranges from 5.2 to 220 eV and the higher harmonic energy can reach 1 KeV. The electron trajectory deviation was controlled to within 5 mu m to maintain a constant optical axis and satisfy the beam dynamic requirements.
Self-organization phenomenon and the edge of chaos in traffic flow dynamics
(2003)
Lan, LW
;
Lin, FY
;
Wang, YP
;
運輸與物流管理系註：原交通所+運管所
;
Department of Transportation and Logistics Management
According to the complexity theory, a self-organization phenomenon might exist when the phase shifts from order (non-congested) to chaos (congested) state within a system. In this paper, cellular automaton (CA) traffic simulator is applied to investigate the self-organization forming process as the traffic density grows. Real traffic data are used to examine whether the power law, an indicator of self-organization phenomenon, exists or not. Our empirical evidence on a two-lane freeway shows that self-organization phenomenon appears when the density exceeds 45% (or 60 pcu/km); however, the edge of chaos is at a density level of 33.8% (or 45 pcu/km), which should be the starting control point (e.g., ramp metering) for recurrent congestion.
Stretch-wire system for integral magnetic field measurements
(2001-07-21)
Hwang, CS
;
Hong, CH
;
Lin, FY
;
Yang, SL
;
電子物理學系
A stretch-wire system was developed to measure and characterize the first and second magnetic fields integral of insertion devices and the harmonic field components of lattice magnet. This simple wire support structure was built with a reliable high precision, and high-speed automatic measurement system for measuring the transversal field integrals of various kind magnets. The measurement precision of the system is 1.5 G cm (70 G cm(2)) for the first (second) field integral of the insertion devices and 0.01% for the harmonic field components analysis of the lattice magnets. The scanning time for a complete measurement is five minutes for the first and second field integral distribution, and four minutes for the harmonic field components. (C) 2001 Elsevier Science B.V. All rights reserved.
The construction of a 9-pole prototype for SRRC U-10 undulator
(1996-07-01)
Chang, CH
;
Chang, LH
;
Chen, HH
;
Fan, TC
;
Hwang, CS
A 9-pole undulator prototype with a magnetic period length of 10 cm was designed and constructed to examine the mechanical and magnetic field performance. The hybrid permanent magnet structure was optimized by using 2D ''PANDIRA'' and 3D ''TOSCA'' magnetostatic codes. A half period magnet model was also fabricated to verify the magnetic Period length field strength on-axis and the transverse field roll-off within 0.1 % in the good field region of +/- 10 mm at a minimum gap of 22 mm. The end pole configurations, as equipped with either two tunable permanent magnetic rotators or steering coil correctors were designed for minimizing the deviation of the magnetic field strength integrals. The magnet structures were mounted bn a 2 meter long C-frame support structure in which the gap could be moved in parallel and phase motion. The field characteristics, and measurement results between the adjustable gap undulator (AGO) and the hybrid adjustable phase undulator (APU) were also presented.