IBIC2015 - List of Authors (Cheng, W.X.)

Paper	Title	Page
MOPB082	NSLS2 Fill Pattern Monitor and Control	246
	W.X. Cheng, B. Bacha, Y. Hu, O. Singh, G.M. Wang BNL, Upton, Long Island, New York, USA
	NSLS2 storage ring has harmonic number of 1320. Possible fill patterns include multi bunch train(s) followed by ion cleaning gap(s), hybrid fill with single bunch in the ion gap. Storage ring filling pattern can be measured using button BPM sum signal together with high speed digitizer or oscilloscope. Button BPM sum signal typically has dynamic range of 10^-2 to 10^-3. Nonlinearity of BPM sum signal dependence on beam position has been characterized. In preparation for high dynamic single bunch current measurement, a filling pattern monitor system using synchrotron radiation is under development. Besides, the storage ring filling pattern can be controlled using the bunch cleaning function integrated in the bunch-by-bunch feedback system. Results of these two filling pattern monitors and bunch cleaning will be presented.
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MOPB083	Longitudinal Bunch Profile Measurement at NSLS2 Storage Ring	251
	W.X. Cheng, B. Bacha, A. Blednykh, Y. Li, O. Singh BNL, Upton, Long Island, New York, USA
	Longitudinal bunch profile has been measured at NSLS2 storage ring using streak camera. From the measured profile, bunch lengthening and synchronous phase information can be derived to study the single bunch collective effect. Single bunch lengthening effect has been measured for bare lattice and for other lattices with different insertion devices. The streak camera can also be setup for other beam physics studies, for example to measure the injection beam dynamics and fast ion effects. Y-z imaging was measured using cylindrical lenses. Single bunch y-z profile was measured at threshold current.
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TUPB086	Observation of Ion-induced Instabilities at NSLS2 Storage Ring	557
	W.X. Cheng, Y. Li, B. Podobedov BNL, Upton, Long Island, New York, USA
	NSLS2 storage ring has been commissioned and is open for user operations. At relatively low beam current (~ 25mA) multi-bunch fills, ion-induced instabilities have been observed. For the present user operations, 150mA of total beam current is filled in ~1000 bunches, fast ion is the dominant instability at the NSLS2 storage ring. Although the ion-induced dipole motions can be suppressed using bunch by bunch (BxB) feedback system and it is expected to decrease in severity as the vacuum conditioning progresses further, a thorough understanding and characterization of this effect is still important, especially in preparation to the future 500mA operations. A number of ion instability related studies, mostly parasitic to other machine activities, have been carried out at various fill patterns and beam currents. Preliminary measurement results are reported in this paper.
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THALA02	Characterization of NSLS2 Storage Ring Beam Orbit Stability	625
	W.X. Cheng, K. Ha, J. Mead, B. Podobedov, O. Singh, Y. Tian, L. Yu BNL, Upton, Long Island, New York, USA
	Similar to other advanced third generation light sources, NSLS2 storage ring has stringent requirements on beam orbit stability. NSLS2 BPMs can be synchronously triggered to record turn by turn or fast acquisition 10kHz data. Spectrum of these data reveals various beam motion frequencies and it has been characterized at various machine conditions. Compared to the ground motion and utility system vibration spectra, beam motion introduced by the vibrations can be identified. An algorithm to locate possible noise sources from the measured spectrum has been developed. Preliminary results of locating orbit sources will be discussed in this paper as well.
	Slides THALA02 [2.776 MB]
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Paper

Title

Page

NSLS2 Fill Pattern Monitor and Control

246

W.X. Cheng, B. Bacha, Y. Hu, O. Singh, G.M. Wang
BNL, Upton, Long Island, New York, USA

NSLS2 storage ring has harmonic number of 1320. Possible fill patterns include multi bunch train(s) followed by ion cleaning gap(s), hybrid fill with single bunch in the ion gap. Storage ring filling pattern can be measured using button BPM sum signal together with high speed digitizer or oscilloscope. Button BPM sum signal typically has dynamic range of 10^-2 to 10^-3. Nonlinearity of BPM sum signal dependence on beam position has been characterized. In preparation for high dynamic single bunch current measurement, a filling pattern monitor system using synchrotron radiation is under development. Besides, the storage ring filling pattern can be controlled using the bunch cleaning function integrated in the bunch-by-bunch feedback system. Results of these two filling pattern monitors and bunch cleaning will be presented.

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reference for this paper to ※ BibTeX, ※ LaTeX, ※ Text, ※ RIS/RefMan, ※ EndNote (xml)

MOPB083

Longitudinal Bunch Profile Measurement at NSLS2 Storage Ring

251

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

Longitudinal bunch profile has been measured at NSLS2 storage ring using streak camera. From the measured profile, bunch lengthening and synchronous phase information can be derived to study the single bunch collective effect. Single bunch lengthening effect has been measured for bare lattice and for other lattices with different insertion devices. The streak camera can also be setup for other beam physics studies, for example to measure the injection beam dynamics and fast ion effects. Y-z imaging was measured using cylindrical lenses. Single bunch y-z profile was measured at threshold current.

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reference for this paper to ※ BibTeX, ※ LaTeX, ※ Text, ※ RIS/RefMan, ※ EndNote (xml)

TUPB086

Observation of Ion-induced Instabilities at NSLS2 Storage Ring

557

W.X. Cheng, Y. Li, B. Podobedov
BNL, Upton, Long Island, New York, USA

NSLS2 storage ring has been commissioned and is open for user operations. At relatively low beam current (~ 25mA) multi-bunch fills, ion-induced instabilities have been observed. For the present user operations, 150mA of total beam current is filled in ~1000 bunches, fast ion is the dominant instability at the NSLS2 storage ring. Although the ion-induced dipole motions can be suppressed using bunch by bunch (BxB) feedback system and it is expected to decrease in severity as the vacuum conditioning progresses further, a thorough understanding and characterization of this effect is still important, especially in preparation to the future 500mA operations. A number of ion instability related studies, mostly parasitic to other machine activities, have been carried out at various fill patterns and beam currents. Preliminary measurement results are reported in this paper.

Export •

reference for this paper to ※ BibTeX, ※ LaTeX, ※ Text, ※ RIS/RefMan, ※ EndNote (xml)

THALA02

Characterization of NSLS2 Storage Ring Beam Orbit Stability

625

W.X. Cheng, K. Ha, J. Mead, B. Podobedov, O. Singh, Y. Tian, L. Yu
BNL, Upton, Long Island, New York, USA

Similar to other advanced third generation light sources, NSLS2 storage ring has stringent requirements on beam orbit stability. NSLS2 BPMs can be synchronously triggered to record turn by turn or fast acquisition 10kHz data. Spectrum of these data reveals various beam motion frequencies and it has been characterized at various machine conditions. Compared to the ground motion and utility system vibration spectra, beam motion introduced by the vibrations can be identified. An algorithm to locate possible noise sources from the measured spectrum has been developed. Preliminary results of locating orbit sources will be discussed in this paper as well.

Slides THALA02 [2.776 MB]

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reference for this paper to ※ BibTeX, ※ LaTeX, ※ Text, ※ RIS/RefMan, ※ EndNote (xml)