| Paper | Title | Page |
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| MOPD079 | A Novel Synchrotron Radiation Interferometer for the Australian Synchrotron | 879 |
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A new arrangement for the synchrotron radiation interferometer was proposed - as far as is known, it is unique in the world. The Young's-type interferometer is composed of two independent and optically identical paths, each with a single slit on a motorised translating stage. These two single slit patterns are interfered to produce a double slit diffraction pattern. This arrangement permits rapid scanning of the profile of fringe visibility as a function of slit separation. The interferometer was used on two beamlines at the Australian Synchrotron, the optical diagnostic and infrared beamlines. The interferometer was used to measure the coherence of the photon beam created by the electron beam source, for normal and low emittance couplings. A large change in fringe visibility was observed, proving the experimental arrangement. The interferometer was validated in the measurement of the width of a hard-edged single slit, akin to Thompson and Wolf's diffractometer. Optical simulations and measurements inform proposed modifications to the optical diagnostic beamline, so as to implement the interferometer as a regular diagnostic tool. |
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| TUPD026 | Impedance Effects in the Australian Synchrotron Storage Ring | 1979 |
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The Australian Synchrotron storage ring must maintain a stable electron beam for user operations. The impedance characteristics of the storage ring can give rise to instabilities that adversely affect the beam quality and need to be well understood. Collective effects driven by the resistive wall impedance are particularly relevant at the Australian synchrotron and their strengths are enhanced by small gap insertion devices, such as IVUs. This study will explore the impedance issues identified in the Australian Synchrotron storage ring and current mitigation techniques. |
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| WEPEA003 | Time Resolved Tune Measurements and Stability Analysis of the Australian Synchrotron Booster | 2472 |
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The Australian Synchrotron booster synchrotron accelerates electrons from 100 MeV to 3 GeV in 600 ms. The fractional tune components that were measured are presented in two graphical formats showing the time-resolved measurement of the horizontal and vertical tunes. This experiment demonstrated that the current in the booster was extremely sensitive to the ratio of BF to BD combined-function magnets. Large variations of the fractional tunes were found to follow the differences in the gradients of the BD and BF combined-function magnet ramping curves and with this knowledge, alterations were made to the ramping table increasing the efficiency of the booster by on average 40%. Rapid fluctuation of the tunes meant that it could not be distinguished during the first 80ms of the ramp. Multiple side bands to the revolution harmonic were visible during a minimal sweep time of 2.5ms, during this first 80ms. |
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| WEPEB027 | Preliminary Operational Experiences of a Bunch-by-bunch Transverse Feedback System at the Australian Synchrotron | 2743 |
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The Australian Synchrotron storage ring has a resistive wall instability in the vertical plane. Presently this instability is being controlled by increasing the vertical chromaticity. However new in-vacuum insertion devices that significantly increase the ring impedance may demand chromatic corrections beyond the capabilities of the sextupole magnets. A transverse bunch-by-bunch feedback system has been commissioned to combat the vertical instability* and provide beam diagnostics**. A high frequency narrow band mode that could not be damped was initial encountered with IVUs at minimum gap preventing the system from being implemented during user beam. Tuning of the bunch fill pattern, the digital filters and mapping out the system response lead to a configuration for user mode operations. * Spencer, M.J. et. al. EPAC'08, Genoa, Italy |