Browsing by Author "Hwang, CS"

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Different kinds of analysis methods on a rectangular combined function bending magnet
(1996-12-11)
Hwang, CS
;
Chang, CH
;
Tseng, PK
;
Uen, TM
;
LeDuff, J
Magnetic field features of a rectangular combined function bending magnet are different from the sector magnet. A strong edge focusing factor (i.e., thin lens effect) intrinsically exists at the two magnet edges for the rectangular bending magnet. Therefore, in this study, we develop two kinds of Hall probe mapping trajectory with four analysis methods to measure and analyze the bending magnet's field behavior. A sufficient correlation among the four methods is an important feature. Those methods are individually used to derive the pole face tilt and bent, the effective magnetic length and to check the specification establish by the beam dynamics group. As for the two mapping methods, one is called ''Radial Mapping'' whose mapping trajectories in the longitudinal direction (s-axis) follow the different are lengths of radius rho+/-r and the transverse trajectories follow the radial displacement +/-r perpendicular to the are trajectory. The other one is called ''Lamination Mapping'' whose mapping trajectories in the longitudinal direction follow the constant are length of circle radius rho and the transverse trajectories follow the transverse axis displacement +/-x parallel to the lamination direction. This study also discusses the differences between those two mapping methods. Results obtained from the harmonic field distribution along the longitudinal direction (including the fringing field) and the main components of the integral strength are compared. The subsequent error of the four analysis methods is 0.01% for the dipole strength and 0.3% for the quadrupole strength individually. According to the specifications, those analysis errors are acceptable. Meanwhile, the accuracies of different methods for the higher multipole strengths are all within tolerances. The peculiar sextupole field behavior at the two magnet edges from the different mapping methods is owing to the effective magnet pole face that will be discussed.
Different kinds of analysis methods on a rectangular combined function bending magnet
(1996-12-11)
Hwang, CS
;
Chang, CH
;
Tseng, PK
;
Uen, TM
;
LeDuff, J
Magnetic field features of a rectangular combined function bending magnet are different from the sector magnet. A strong edge focusing factor (i.e., thin lens effect) intrinsically exists at the two magnet edges for the rectangular bending magnet. Therefore, in this study, we develop two kinds of Hall probe mapping trajectory with four analysis methods to measure and analyze the bending magnet's field behavior. A sufficient correlation among the four methods is an important feature. Those methods are individually used to derive the pole face tilt and bent, the effective magnetic length and to check the specification establish by the beam dynamics group. As for the two mapping methods, one is called ''Radial Mapping'' whose mapping trajectories in the longitudinal direction (s-axis) follow the different are lengths of radius rho+/-r and the transverse trajectories follow the radial displacement +/-r perpendicular to the are trajectory. The other one is called ''Lamination Mapping'' whose mapping trajectories in the longitudinal direction follow the constant are length of circle radius rho and the transverse trajectories follow the transverse axis displacement +/-x parallel to the lamination direction. This study also discusses the differences between those two mapping methods. Results obtained from the harmonic field distribution along the longitudinal direction (including the fringing field) and the main components of the integral strength are compared. The subsequent error of the four analysis methods is 0.01% for the dipole strength and 0.3% for the quadrupole strength individually. According to the specifications, those analysis errors are acceptable. Meanwhile, the accuracies of different methods for the higher multipole strengths are all within tolerances. The peculiar sextupole field behavior at the two magnet edges from the different mapping methods is owing to the effective magnet pole face that will be discussed.
Features of the magnetic field of a rectangular combined function bending magnet
(1996-07-01)
Hwang, CS
;
Chang, CH
;
Hwang, GJ
;
Uen, TM
;
Tseng, PK
Magnetic field features of the combined function bending magnet with dipole and quadrupole field components are essential for the successful operation of the electron beam trajectory. These fields also dominate the photon beam quality, The vertical magnetic field B-y(X,Y) calculation is performed by a computer code ''MAGNET'' at the magnet center ( s=0 ). Those results are compared with the 2-D field measurement by the Hall probe mapping system. Also detailed survey has been made of the harmonic field strength and the main features of the fundamental integrated strength, effective length, magnetic symmetry, tilt of the pole face, offset of the field center and the fringe field. The end shims that compensate for the strong end negative sextupole field to increase the good field region for the entire integrated strength are discussed. An important physical feature of this combined function bending magnet is the constant ratio of dipole and quadrupole strength integral Bds/integral Gds which is expressed as a function of excitation current in the energy range 0.6 to 1.5 GeV.
Highly automatic measurement system for three orthogonal magnetic moments of a permanent magnet block
(1996-05-01)
Hwang, CS
;
Yeh, ST
;
Teng, PK
;
Uen, TM
;
電子物理學系
A highly automatic system with a three-angle rotation mechanism has been designed and constructed to measure several thousand permanent magnet blocks. The system's main features include its high speed, highly automatic measurement, and the ease with which the different size magnet blocks can be installed and removed. This system provides precise and accurate measurements of the three orthogonal magnetic moment components to accurately characterize each block, as deemed necessary to assess the field quality of undulators and wigglers. A three-angle in rotation mechanism, together with a simple mathematical algorithm is used to measure and analyze the magnetic moments of the magnet block. The system includes the Helmholtz coil pair, block holder, the three-degree rotation mechanism, and the control and data acquisition system. A power train system consists of one motor coupled with a nonmagnetic stainless steel for 360 degrees rotation and two motors individually coupled with two groups of nonmagnetic time belts for rotation angles of 0 degrees, 180 degrees, 0 degrees, and 90 degrees. The control system uses a microcomputer together with a stepping motor control card and a digital fluxmeter connected by the general purpose interface bus. The measurement speed of this system is 40 blocks per h. One reference magnet was measured, with those results verifying the long term precision of the order of 0.04% for the easy component and 0.02 degrees for two minor components. The coil-pair geometry factor is calibrated via the voltage-field reciprocity principle, indicating that the system absolute accuracy is around 0.43%. (C) 1996 American Institute of Physics.
Magnetic field features of various magnetic circuits on the sextupole magnet
(1996-10-01)
Hwang, CS
;
Chang, CH
;
Fan, TC
;
Uen, TM
;
Tseng, PK
In this study, two adjacent sextants were partially cut from one side of a sextupole magnet in order to accommodate the electron beam bending chamber associated with a three x-ray beam dine chamber. The yoke cutting of these two sextants creates a different magnetic circuit which induces several forbidden fields. Meanwhile, the fundamental strength of this magnetic circuit is less than that of the normal on cut sextupole magnets in the storage ring. An induced forbidden field and the lessened sextupole strength originated from the saturation effect occurring at the magnet's yoke cutting side. Therefore, an extra closed-loop magnetic circuit is added across the two adjacent sextants to compensate for the yoke's smaller core area. This extra magnetic circuit can eliminate the saturation effect which induces asymmetric field behavior. It can also compensate for the lessened sextupole strength. In this work, the field distribution for various excitation currents related to the three magnetic circuits were measured. The field measurement results with various excitation currents tell us that the field saturation phenomena create the asymmetry field, forbidden field, and the lessened sextupole strength of the yoke cut magnetic circuit.
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.
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.