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Beam lifetime investigations at SRRC

Description: The beam lifetime of the 1.3 GeV storage ring TLS (Taiwan Light Source) at SRRC was studied. Contributions of the gas scattering lifetime and Touschek scattering lifetime were measured. Effects of insertion devices, RF energy acceptance, chromaticity setting, transverse emittance coupling strength, bunch length, bunch current, etc. on the beam lifetime were measured. It is observed that this machine is Touschek lifetime dominated provided that the transverse emittance coupling strength is low enough and bunch current is reasonably high. In the multibunch users mode it is required to have a longer lifetime; some possible actions to increase beam lifetime have been proposed or implemented.
Date: October 1, 1996
Creator: Kuo, C.C.; Chang, H.P.; Wang, M.H. & Weng, W.T.
Partner: UNT Libraries Government Documents Department

Damping rates of the SRRC storage ring

Description: The SRRC storage ring is a low emittance synchrotron radiation machine with nominal operation energy 1.3 GeV. The design damping time due to synchrotron radiation is 10.7, 14.4, 8.7 ms for the horizontal, vertical and longitudinal plane, respectively. The authors measured the real machine damping time as a function of bunch current, chromaticity, etc. To damp the transverse beam instability, especially in the vertical plane, they need to increase chromaticity to large positive value. The damping rates are much larger than the design values. Landau damping contribution in the longitudinal plane is quite large, especially in the multibunch mode. The estimated synchrotron tune spread from the Landau damping is in agreement with the measured coherent longitudinal coupled bunch oscillation amplitude.
Date: June 1, 1995
Creator: Hsu, K. T.; Kuo, C. C.; Lau, W. K. & Weng, W. T.
Partner: UNT Libraries Government Documents Department

Performance of the SRRC storage ring and wiggler commissioning

Description: A 1.3 GeV synchrotron radiation storage ring at SRRC has been operated for more than a year since October 1993. Starting from April 1994, the machine has been open to the user community. In February 1995, the authors installed a wiggler magnet of 1.8 tesla 25-pole in the ring and successfully commissioned. The machine was scheduled for the users` runs from the middle of April this year. The authors describe the performance of the machine without wiggler magnet system and then report the wiggler effects on the beam dynamics of the storage ring, e.g., tune shift, beta-beating, orbit change, nonlinear dynamics effect, etc. Some measurements are compared with the model prediction and agreement between them was fairly good. Possible actions to minimize wiggler effects have been taken, such as orbit correction as a function wiggler gap change. The machine improvement projects, such as longitudinal and transverse damping systems as well as orbit stability feedback system are under construction and will be in use soon.
Date: May 1, 1995
Creator: Kuo, C.C.; Hsu, K.T. & Luo, G.H.
Partner: UNT Libraries Government Documents Department

Computer Simulation of Equilibrium Electron Beam Distribution in the Proximity of 4th Order Single Nonlinear Resonance

Description: The beam distribution of particles in a storage ring can be distorted in the presence of nonlinear resonances. Computer simulation is used to study the equilibrium distribution of an electron beam in the presence of a single 4th order nonlinear resonance in a storage ring. Its result is compared with that obtained using an analytical approach by solving the Fokker-Planck equation to first order in the resonance strength. The effect of resonance on quantum lifetime of electron beam is also compared and investigated.
Date: May 9, 2005
Creator: Kuo, C.-C.; Tsai, H.-J.; Ueng, T.-S.; /NSRRC, Taiwan; Chao, A. & /SLAC
Partner: UNT Libraries Government Documents Department

Performance of the TLS at SRRC

Description: 3-year operation experiences of the 1.3 GeV synchrotron radiation facility at SRRC are presented. Two insertion devices (W20 and U10p) are installed in the storage ring; more are under construction. Single bunch instabilities were measured and ring impedance calculated. Both transverse and longitudinal coupled bunch instabilities were observed and corresponding feedback system constructed. The transverse feedback system is now routinely operated. A fast global orbit feedback system is in the development stage. Lifetime is about 5 hours at 200 mA; plans to increase lifetime are proposed. At present, the machine can be operated at nominal design energy 1.3 GeV with full energy injection and ramped up to 1.5 GeV at 200 mA.
Date: October 1, 1996
Creator: Liu, Y.C.; Chen, J.R.; Chang, C.H.; Hsu, K.T. & Kuo, C.C
Partner: UNT Libraries Government Documents Department

Performance of the transverse coupled-bunch feedback system in the SRRC

Description: A transverse feedback system has been implemented and commissioned in the SRRC storage ring to suppress transverse coupled-bunch oscillations of the electron beam. The system includes transverse oscillation detectors, notch filter, baseband quadrature processing circuitry, power amplifiers, and kickers. To control a large number of transverse coupled-bunch modes, the system is broad-band, bunch-by- bunch in nature. Because the system is capable of bunch-by-bunch correction, it can also be useful for suppressing instabilities introduced by ions. The sextupole strength was then reduced to improve dynamic aperture and hence lifetime of the storage ring.
Date: October 1, 1996
Creator: Hsu, K.T.; Kuo, C.C.; Kuo, C.H.; Lin, K.K.; Ueng, T.S. & Weng, W.T.
Partner: UNT Libraries Government Documents Department

VERTICAL BEAM SIZE CONTROL IN TLS AND TPS.

Description: Vertical beam size control is an important issue in the light source operations. The horizontal-vertical betatron coupling and vertical dispersion were measured and corrected to small values in the TLS 1.5 GeV storage ring. Estimated beam sizes are compared with the measured values. By employing an effective transverse damping system, the vertical beam blow-up due to transverse coherent instabilities, such as the fast-ion beam instability, was suppressed. As a result, the light source is very stable. In NSRRC we are designing an ultra low emittance 3-GeV storage ring and its designed vertical beam size could be as small as a few microns. The ground and mechanic vibration effects, and coherent instabilities could spoil the expected photon brightness due to blow-up of the vertical beam size if not well taken care of. The contributions of these effects to vertical beam size increase will be evaluated and the counter measures to minimize them will be proposed and reported in this paper.
Date: June 26, 2006
Creator: KUO, C.C.; CHEN, J.R.; CHOU, P.J.; CHANG, H.P.; HSU, K.T.; LUO, G.H. et al.
Partner: UNT Libraries Government Documents Department

SPEAR3 Commissioning

Description: The successful commissioning of the new SPEAR3 light source at the Stanford Synchrotron Radiation Laboratory (SSRL) will be reviewed. Orbit control, beam-based alignment, and an orbit interlock were commissioned. Orbit motion was characterized as a function of frequency. The linear optics was corrected for ID focusing and coupling errors. The nonlinear optics were investigated with dynamic aperture measurements as a function of energy and tune.
Date: May 9, 2005
Creator: Harkay, K.; Sajaev, V.; Boland, M. J.; Tan, Y. E.; Krinsky, S.; Podobedov, B. et al.
Partner: UNT Libraries Government Documents Department