NAPAC2016 - List of Authors (Li, Y.)

Paper	Title	Page
TUPOA71	Beam Stability During Top Off Operation at NSLS-II Storage Ring	425
	W.X. Cheng, B. Bacha, Y. Li, O. Singh, Y. Tian BNL, Upton, Long Island, New York, USA
	NSLS-II storage ring started top off operation since Oct 2015. User operation current has been gradually increased to 250mA. Observations of beam stabilities during top-off operations will be presented. Total beam current was typically maintained within ±0.5% and bunch to bunch current variation was less than 20%. Injection transition during top-off was measured bunch by bunch digitizer, and BPM to analyze the orbit motion at various bandwidths (turn by turn, 10kHz and 10Hz rate). Coupled bunch unstable motions were monitored. As the vacuum pressure improves, fast-ion instability is not as severe compared to early stage of commissioning/operation, but still observed as the dominant instability. Resistive wall instability is noticed as more in-vacuum-undulator (IVU) gaps closed. xBPM measured photon stability and electron beam stability at top off injection have been evaluated. Short term and long term orbit stabilities will be reported.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-TUPOA71
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TUPOB54	Using Square Matrix to Realize Phase Space Manipulation and Dynamic Aperture Optimization	609
	Y. Li, L. Yu BNL, Upton, Long Island, New York, USA
	We introduce a new method of using square matrix to realize phase space manipulation and dynamic aperture optimization in storage rings. Both the tracking simulation and the experimental observation in the NSLS-II ring lattice are presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-TUPOB54
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WEPOB65	Experiments of Lossless Crossing - Resonance With Tune Modulation by Synchrotron Oscillations	1036
	G.M. Wang, B. Holub, Y. Li, J. Rose, T.V. Shaftan, V.V. Smaluk BNL, Upton, Long Island, New York, USA
	It had become a standard practice to constrain particle's tune footprint while designing the storage ring lattice so that the tunes fit between harmful resonances that limit ring dynamic aperture (DA). However, in recent ultra-bright light source design, the nonlinearities of storage ring lattices are much enhanced as compared with the 3rd generation light source one. It is becoming more and more difficult to keep the off-momentum tune footprint confined and even more, the solution cannot be found to confine off-energy tune footprint in certain cases. The questions have been asked whether crossing of a resonance stopband from off-momentum particle will necessarily lead to particle loss. In NSLS-II, we modified the lattice working point to mimic machine tune footprint crossing half integer with beam synchrotron oscillation excitation and demonstrated that beam can cross a resonance without loss with control of stopband width and high order chromaticity.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-WEPOB65
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Paper

Title

Page

Beam Stability During Top Off Operation at NSLS-II Storage Ring

425

W.X. Cheng, B. Bacha, Y. Li, O. Singh, Y. Tian
BNL, Upton, Long Island, New York, USA

NSLS-II storage ring started top off operation since Oct 2015. User operation current has been gradually increased to 250mA. Observations of beam stabilities during top-off operations will be presented. Total beam current was typically maintained within ±0.5% and bunch to bunch current variation was less than 20%. Injection transition during top-off was measured bunch by bunch digitizer, and BPM to analyze the orbit motion at various bandwidths (turn by turn, 10kHz and 10Hz rate). Coupled bunch unstable motions were monitored. As the vacuum pressure improves, fast-ion instability is not as severe compared to early stage of commissioning/operation, but still observed as the dominant instability. Resistive wall instability is noticed as more in-vacuum-undulator (IVU) gaps closed. xBPM measured photon stability and electron beam stability at top off injection have been evaluated. Short term and long term orbit stabilities will be reported.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-TUPOA71

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPOB54

Using Square Matrix to Realize Phase Space Manipulation and Dynamic Aperture Optimization

609

Y. Li, L. Yu
BNL, Upton, Long Island, New York, USA

We introduce a new method of using square matrix to realize phase space manipulation and dynamic aperture optimization in storage rings. Both the tracking simulation and the experimental observation in the NSLS-II ring lattice are presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-TUPOB54

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPOB65

Experiments of Lossless Crossing - Resonance With Tune Modulation by Synchrotron Oscillations

1036

G.M. Wang, B. Holub, Y. Li, J. Rose, T.V. Shaftan, V.V. Smaluk
BNL, Upton, Long Island, New York, USA

It had become a standard practice to constrain particle's tune footprint while designing the storage ring lattice so that the tunes fit between harmful resonances that limit ring dynamic aperture (DA). However, in recent ultra-bright light source design, the nonlinearities of storage ring lattices are much enhanced as compared with the 3rd generation light source one. It is becoming more and more difficult to keep the off-momentum tune footprint confined and even more, the solution cannot be found to confine off-energy tune footprint in certain cases. The questions have been asked whether crossing of a resonance stopband from off-momentum particle will necessarily lead to particle loss. In NSLS-II, we modified the lattice working point to mimic machine tune footprint crossing half integer with beam synchrotron oscillation excitation and demonstrated that beam can cross a resonance without loss with control of stopband width and high order chromaticity.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-WEPOB65

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)