| Paper | Title | Page |
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| MOPAB151 | Techniques for Transparent Lattice Measurement and Correction | 483 |
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Funding: Work supported by DOE contract No: DE-SC0012704 NSLS-II storage ring started top off operation since Oct 2015. It has been noticed during the user operation that machine lattice was affected by insertion devices (ID). The storage ring coupling, emittance and lifetime vary when ID gap changes. Lattice characterization was typically carried out with dedicated machine study time with low storage current. Due to collective effect, the lattice at high operation current is different. To characterize the machine lattice during normal user operation with little disturbance, a small portion of beam (~1%) filled in the ion gap can be excited by the bunch by bunch feedback system near betatron frequency. Recent development on BPM electronics enables the gate function to detect partial beam motion in the ring. With the gated BPM turn by turn data from excited bunches, storage ring lattice can be measured and corrected with the well-developed tools. We present in the paper preliminary test results with these tools to characterize the lattice and how it improves the machine performance during user operation. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPAB151 | |
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| MOPAB152 | Precise Synchronous Phase Measurements | 487 |
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Funding: DOE contract No: DE-SC0012704 Precise measurements of storage ring synchronous phase helps to understand the machine impedance and improve the high current performance. We present different methods tested at NSLS-II, including the streak camera measurement, relative phase measurement from a high sampling frequency oscilloscope by comparing the beam signal and reference signal. Both streak camera and scope method have high precision to measure the synchronous phase (<1ps). Other methods to measure the synchronous phase include the I-Q detection from BPM electronics, FPM scope have been tested as well. We have used these systems to study the synchronous phase shift at different beam current, RF voltages and ID gaps. Recent results will be presented and discussed in the paper. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPAB152 | |
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| MOPIK125 | Multi-frequency AC LOCO: A Fast and Precise Technique for Lattice Correction | 831 |
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We developed a novel technique to improve the precision and shorten the measurement time of the LOCO (Linear Optics from Closed Orbits) method at NSLS-II [1]. This technique named AC LOCO is based on a sine-wave (AC) beam excitation via fast correctors typically installed at synchrotron light sources for the fast orbit feedback. The beam oscillations are measured by beam position monitors. The narrow band used for the beam excitation and measurement not only allows us to suppress effectively the beam position noise and also makes simultaneously exciting multiple correctors at different frequencies (multi-frequency mode) possible. We demonstrated at NSLS-II that the new technique provides better lattice corrections and achieves two minutes measurement time in the thirty-frequency mode.
[1] X. Yang et al., 'Fast and precise technique for magnet lattice correction via sine-wave excitation of fast correctors', Phys. Rev. Accel. Beams, vol. 20, p. 054001, 2017. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPIK125 | |
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