Author: Cheng, W.X.
Paper Title Page
MOPAB151 Techniques for Transparent Lattice Measurement and Correction 483
 
  • W.X. Cheng, K. Ha, Y. Li
    BNL, Upton, Long Island, New York, USA
 
  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.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPAB151  
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MOPAB152 Precise Synchronous Phase Measurements 487
 
  • W.X. Cheng, B. Bacha, K. Ha, O. Singh
    BNL, Upton, Long Island, New York, USA
 
  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.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPAB152  
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THPVA095 Storage Ring Injection Kickers Alignment Optimization in NSLS-II 4683
 
  • G.M. Wang, W.X. Cheng, J. Choi, T.V. Shaftan, X. Yang
    BNL, Upton, Long Island, New York, USA
 
  The National Synchrotron Light Source II (NSLS-II) is a state of the art 3 GeV third generation light source at Brookhaven National Laboratory. The SR is designed to work in top-off injection mode. The injection straight includes a septum and four fast kicker magnets with independent amplitude and timing control. Ideally, fast kickers formed a local bump, which is transparent to stored beam during top off injection. Due to mismatch of kicker voltage, timing or waveform, there is residual betatron oscillation and impact normal operation. This paper will present the injection kicker waveform measurement with beam, local and global alignment optimization to in improve top off injection transition.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPVA095  
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