RUPAC2012 - List of Keywords (betatron)

Paper	Title	Other Keywords	Page
TUPPB031	Measurement of Beam Parameters in the VEPP-5 Damping Ring Using Betatron Oscillations Decoherence	damping, electron, positron, synchrotron	385
	A.V. Petrenko, K.V. Astrelina BINP SB RAS, Novosibirsk, Russia
	Funding: RFBR, grant N 09-02-00594-а The measurement of beam parameters during the commissioning of VEPP-5 Damping Ring is presented. Coherent betatron oscillations of the 380-MeV electron beam were induced by a fast kick. Electrostatic beam position monitors were used to obtain the turn-by-turn transverse beam position data. The form and behaviour of the envelope of oscillations are determined by the beam parameters, chromaticity and nonlinear detuning. Beam emittance and energy spread values have been obtained from the analysis of the beam envelope, nonlinear detuning and chromaticity measurements. The results are in a good agreement with theoretical predictions which were made for calibrated model of the Damping Ring. Independent analysis of betatron spectra envelope have been performed for energy spread measurements as well.

TUPPB037	Second-Order Correction in the Isochronous Mode of the Collector Ring (CR) at FAIR	emittance, ion, sextupole, optics	400
	S.A. Litvinov, C. Dimopoulou, A. Dolinskii, O.E. Gorda, F. Nolden, M. Steck, H. Weick GSI, Darmstadt, Germany
	A challenge for nuclear physics is to measure masses of exotic nuclei up to the limits of nuclear existence which are characterized by low production cross-sections and short half-lives. The large acceptance Collector Ring (CR) at FAIR tuned in the isochronous ion-optical mode offers unique possibilities for such measurements. However, the mass-measurement resolution is inversely proportional to the transverse emittance. In order to reach a resolving power of 10⁵ the transverse beam emittance would have to be limited up to 10 mm mrad in both planes, which drastically reduces the transmission of the exotic nuclei. We demonstrate here that the negative influence of the transverse emittance on the mass resolution can be significantly reduced by a proper second-order correction.

WEPPD007	Vertical Size of an Electron Beam at Siberia-2	quadrupole, coupling, sextupole, closed-orbit	578
	A.G. Valentinov, V. Korchuganov, Y.V. Krylov, Y.L. Yupinov NRC, Moscow, Russia
	Brightness of the synchrotron radiation light sources is defined by electron beam sizes at radiation point. Horizontal size depends mainly from designed magnetic structure. Vertical size is defined by two processes: first, betatron coupling between vertical and horizontal motions and second, presence of vertical dispersion function at bending magnets. Vertical dispersion creates non-zero vertical emittance even without coupling. The report is dedicated to methods of vertical beam size decreasing at Siberia-2 storage ring. There are two families of skew-quadrupoles on the ring, one lens of every family in each of 6 cells of the magnetic structure. After analyzing of betatron coupling coefficient equation we stayed only two lenses in each family. As a result family currents for coupling compensation became much lower. In order to decrease vertical dispersion a special algorithm was developed and tested. Vertical dispersion on BPM azimuths was corrected by vertical displacements of sextupoles for chromaticity compensation. Maximal value of the dispersion became four times lower. It leaded to prominent vertical beam size decreasing.

WEPPD008	Energy Ramping at Siberia-2	quadrupole, injection, power-supply, resonance	581
	A.G. Valentinov, V. Korchuganov, Y.V. Krylov, Y.L. Yupinov NRC, Moscow, Russia
	Siberia-2 storage ring has great difference between injection energy 0.45 GeV and working energy 2.5 GeV. Beam lifetime at injection energy is equal to approximately 1 hour. In order to minimize beam losses of the stored beam it is necessary to accelerate energy ramping process. It is not very simple because power supplies of bending magnets, quadrupole lenses and sextupoles have different response time and behavior after changes in regulated current level. Magnetic elements are manufactured from non-laminated iron. It leads to slower field/gradient increasing at high current values. Complicated algorithm with 9 intermediate regimes (collections of power supplies' settings) was developed to produce fast and efficient energy ramping. First, correction of closed orbit, betatron tunes and chromaticity is accomplished in each regime in static conditions. Special file is used to provide acceleration or deceleration of power supplies in dynamic conditions. This scheme allows to compensate betatron tune shifts during energy ramping. Power supplies are not stopped on intermediate regimes; speed of current changing is continuous function of time. This algorithm allowed decreasing ramping time down to 2 minutes 40 seconds. Beam losses are not exceeding 2 – 3%; betatron tune shifts as a rule are lower than 0.01. The algorithm can easily be modified to stop in any intermediate regime.

WEPPD029	Fast Tune Measurement System	booster, kicker, pick-up, synchrotron	611
	E.A. Bekhtenev, V.P. Cherepanov, G.V. Karpov, A.S. Styuf BINP SB RAS, Novosibirsk, Russia
	Tune measurement system developed in Budker Institute of Nuclear Physics provides fast and accurate measurements of fractional part of betatron tunes in electron-positron storage rings and accelerators. The tune measurements rate can achieve 1 kHz. It is especially important for electron-positron accelerators to have tunes measurement data for each phase of accelerating cycle. The developed system is planed to be installed at the NSLS-II Booster Synchrotron. The system can perform up to 330 measurements during 300 ms time interval of Booster energy ramping. The kicking technique is used as measurement method. The kicks are carried out by a radio frequency (RF) pulses. Each RF pulse contains two frequencies and thus can simultaneously excite the horizontal and vertical betatron oscillations. All signal processing including FFT is performed inside FPGA. The tune measurement accuracy is better than 0.0005. The developed system was put into operation at the February 2011 in VEPP-3 electron-positron storage ring at BINP.

WEPPD046	Digital Delay-Line Periodic FIR Filter Layout of Transverse Feedback in the U70	feedback, pick-up, damping, kicker	647
	O.P. Lebedev, N.A. Ignashin, S.V. Ivanov, S.E. Sytov IHEP, Moscow Region, Russia
	A novel architecture of the wide-band transverse feedback system was successfully beam-tested in the U70 proton synchrotron of IHEP-Protvino. It employs a finite-time impulse response (FIR) non-recursive filter layout based on 3 (or 4, optionally) variable (10%) multi-turn digital delay lines. Apart of using these natural-to-DSP components, the configuration involved has, at least, two operational advantages: (1) A single beam pickup layout plus acceptability of an arbitrary betatron phase advance between pickup and kicker. (2) A straightforward rejection of hampering DC and higher rotation frequency harmonic signals from beam position readouts. The latter occurs due to a periodic notch nature inherent in the amplitude-frequency in-out open-loop feedback transfer function. The paper reports on technical solutions implemented, problem-oriented R&D studies, and beam observations.

Paper

Title

Other Keywords

Page

TUPPB031

Measurement of Beam Parameters in the VEPP-5 Damping Ring Using Betatron Oscillations Decoherence

damping, electron, positron, synchrotron

385

A.V. Petrenko, K.V. Astrelina
BINP SB RAS, Novosibirsk, Russia

Funding: RFBR, grant N 09-02-00594-а
The measurement of beam parameters during the commissioning of VEPP-5 Damping Ring is presented. Coherent betatron oscillations of the 380-MeV electron beam were induced by a fast kick. Electrostatic beam position monitors were used to obtain the turn-by-turn transverse beam position data. The form and behaviour of the envelope of oscillations are determined by the beam parameters, chromaticity and nonlinear detuning. Beam emittance and energy spread values have been obtained from the analysis of the beam envelope, nonlinear detuning and chromaticity measurements. The results are in a good agreement with theoretical predictions which were made for calibrated model of the Damping Ring. Independent analysis of betatron spectra envelope have been performed for energy spread measurements as well.

TUPPB037

Second-Order Correction in the Isochronous Mode of the Collector Ring (CR) at FAIR

emittance, ion, sextupole, optics

400

S.A. Litvinov, C. Dimopoulou, A. Dolinskii, O.E. Gorda, F. Nolden, M. Steck, H. Weick
GSI, Darmstadt, Germany

A challenge for nuclear physics is to measure masses of exotic nuclei up to the limits of nuclear existence which are characterized by low production cross-sections and short half-lives. The large acceptance Collector Ring (CR) at FAIR tuned in the isochronous ion-optical mode offers unique possibilities for such measurements. However, the mass-measurement resolution is inversely proportional to the transverse emittance. In order to reach a resolving power of 10⁵ the transverse beam emittance would have to be limited up to 10 mm mrad in both planes, which drastically reduces the transmission of the exotic nuclei. We demonstrate here that the negative influence of the transverse emittance on the mass resolution can be significantly reduced by a proper second-order correction.

WEPPD007

Vertical Size of an Electron Beam at Siberia-2

quadrupole, coupling, sextupole, closed-orbit

578

A.G. Valentinov, V. Korchuganov, Y.V. Krylov, Y.L. Yupinov
NRC, Moscow, Russia

Brightness of the synchrotron radiation light sources is defined by electron beam sizes at radiation point. Horizontal size depends mainly from designed magnetic structure. Vertical size is defined by two processes: first, betatron coupling between vertical and horizontal motions and second, presence of vertical dispersion function at bending magnets. Vertical dispersion creates non-zero vertical emittance even without coupling. The report is dedicated to methods of vertical beam size decreasing at Siberia-2 storage ring. There are two families of skew-quadrupoles on the ring, one lens of every family in each of 6 cells of the magnetic structure. After analyzing of betatron coupling coefficient equation we stayed only two lenses in each family. As a result family currents for coupling compensation became much lower. In order to decrease vertical dispersion a special algorithm was developed and tested. Vertical dispersion on BPM azimuths was corrected by vertical displacements of sextupoles for chromaticity compensation. Maximal value of the dispersion became four times lower. It leaded to prominent vertical beam size decreasing.

WEPPD008

Energy Ramping at Siberia-2

quadrupole, injection, power-supply, resonance

581

A.G. Valentinov, V. Korchuganov, Y.V. Krylov, Y.L. Yupinov
NRC, Moscow, Russia

Siberia-2 storage ring has great difference between injection energy 0.45 GeV and working energy 2.5 GeV. Beam lifetime at injection energy is equal to approximately 1 hour. In order to minimize beam losses of the stored beam it is necessary to accelerate energy ramping process. It is not very simple because power supplies of bending magnets, quadrupole lenses and sextupoles have different response time and behavior after changes in regulated current level. Magnetic elements are manufactured from non-laminated iron. It leads to slower field/gradient increasing at high current values. Complicated algorithm with 9 intermediate regimes (collections of power supplies' settings) was developed to produce fast and efficient energy ramping. First, correction of closed orbit, betatron tunes and chromaticity is accomplished in each regime in static conditions. Special file is used to provide acceleration or deceleration of power supplies in dynamic conditions. This scheme allows to compensate betatron tune shifts during energy ramping. Power supplies are not stopped on intermediate regimes; speed of current changing is continuous function of time. This algorithm allowed decreasing ramping time down to 2 minutes 40 seconds. Beam losses are not exceeding 2 – 3%; betatron tune shifts as a rule are lower than 0.01. The algorithm can easily be modified to stop in any intermediate regime.

WEPPD029

Fast Tune Measurement System

booster, kicker, pick-up, synchrotron

611

E.A. Bekhtenev, V.P. Cherepanov, G.V. Karpov, A.S. Styuf
BINP SB RAS, Novosibirsk, Russia

Tune measurement system developed in Budker Institute of Nuclear Physics provides fast and accurate measurements of fractional part of betatron tunes in electron-positron storage rings and accelerators. The tune measurements rate can achieve 1 kHz. It is especially important for electron-positron accelerators to have tunes measurement data for each phase of accelerating cycle. The developed system is planed to be installed at the NSLS-II Booster Synchrotron. The system can perform up to 330 measurements during 300 ms time interval of Booster energy ramping. The kicking technique is used as measurement method. The kicks are carried out by a radio frequency (RF) pulses. Each RF pulse contains two frequencies and thus can simultaneously excite the horizontal and vertical betatron oscillations. All signal processing including FFT is performed inside FPGA. The tune measurement accuracy is better than 0.0005. The developed system was put into operation at the February 2011 in VEPP-3 electron-positron storage ring at BINP.

WEPPD046

Digital Delay-Line Periodic FIR Filter Layout of Transverse Feedback in the U70

feedback, pick-up, damping, kicker

647

O.P. Lebedev, N.A. Ignashin, S.V. Ivanov, S.E. Sytov
IHEP, Moscow Region, Russia

A novel architecture of the wide-band transverse feedback system was successfully beam-tested in the U70 proton synchrotron of IHEP-Protvino. It employs a finite-time impulse response (FIR) non-recursive filter layout based on 3 (or 4, optionally) variable (10%) multi-turn digital delay lines. Apart of using these natural-to-DSP components, the configuration involved has, at least, two operational advantages: (1) A single beam pickup layout plus acceptability of an arbitrary betatron phase advance between pickup and kicker. (2) A straightforward rejection of hampering DC and higher rotation frequency harmonic signals from beam position readouts. The latter occurs due to a periodic notch nature inherent in the amplitude-frequency in-out open-loop feedback transfer function. The paper reports on technical solutions implemented, problem-oriented R&D studies, and beam observations.