HB2012 - List of Authors (Chorniy, O.)

Paper

Title

Page

A Method to Measure the Incoherent Synchrotron Frequencies in Bunches

46

O. Chorniy, H. Reeg
GSI, Darmstadt, Germany

The method of measuring the incoherent synchrotron frequencies in a stationary bunch is presented. It can be shown that by measuring the local current at a fixed coordinate in RF bucket the corresponding incoherent synchrotron frequency can be obtained. Test calculations were done using simulation data where longitudinal space charge effects were included. The incoherent frequencies obtained with method are in a good agreement with theory. In real experiment, the incoherent frequencies were determined from bunch profiles recorded in the SIS18 with low intensity beam at injection energy. Bunch profiles were measured with a new Fast Current Transformer which has a relatively broad frequency range. The profiles were recorded using 8 bit resolution oscilloscope. The frequency spectra of local current fluctuation at different longitudinal positions were obtained numerically. The strongest lines in these spectra were at positions of theoretically expected incoherent frequencies. In this paper the method is described in details, the comparison of incoherent frequencies obtained from the simulation and measurement data with theoretical solutions is shown.

MOP205

Intense Heavy-Ion Bunches in Dual-harmonic RF Systems

51

M. Mehler, O. Chorniy
GSI, Darmstadt, Germany
O. Boine-Frankenheim
TEMF, TU Darmstadt, Darmstadt, Germany
O.K. Kester
IAP, Frankfurt am Main, Germany

For the synchrotron's SIS-18 and SIS-100 (FAIR) a dual-harmonic RF system with the harmonic numbers h1=2, h2=4 and h1=10, h2=20 respectively is planned. Such systems flatten the bunch form and increase the bunching factor Bf therefore reducing the transverse space charge force. For high currents cavity beam loading and potential-well distortion will deform the flattened bunch shape and lead to phase shifts. Optimized settings for the difference between the two RF phases and for the synchronous phase of the main RF harmonic are an option to reduce these effects. In this contribution we will analyse further aspects of the matched bunch distribution, possible instabilities of the obtained distribution will be discussed and results of machine experiments in SIS-18 will be presented.

TUO1C05

Measurements and Interpretation of the Betatron Tune Spectra of High Intensity Bunched Beam at SIS-18

310

R. Singh, O. Chorniy, P. Forck, R. Haseitl, W. Kaufmann, P. Kowina, K. Lang
GSI, Darmstadt, Germany
O. Boine-Frankenheim, R. Singh, T. Weiland
TEMF, TU Darmstadt, Darmstadt, Germany

The paper presents the status of the transverse tune measurements in the synchrotron SIS18 at GSI. Presently, there are two systems for tune measurements in operation in the SIS18, namely TOPOS (Tune, Orbit and POsition measurement System) and BBQ (Base Band tune measurement system). The first one is a digital system where the BPM signal is digitized and the bunch position is calculated numerically. The second system is an analog system, where the transverse bunch motion is detected using peak detector. Band limited noise and chirp excitations were used to excite the betatron oscillations. Measurements of the betatron tune spectra were done at injection energy at medium and high intensities. In the frequency spectra a number of peaks around the position of betatron tune were seen. The peaks can be attributed to different bunch head-tail modes which were observed in time domain. These modes were dependent on the beam intensity. In this paper we compare the tune spectra measured at high beam intensity with the theoretical model for the space charge affected head-tail modes.

Slides TUO1C05 [1.315 MB]

Paper	Title	Page
MOP204	A Method to Measure the Incoherent Synchrotron Frequencies in Bunches	46
	O. Chorniy, H. Reeg GSI, Darmstadt, Germany
	The method of measuring the incoherent synchrotron frequencies in a stationary bunch is presented. It can be shown that by measuring the local current at a fixed coordinate in RF bucket the corresponding incoherent synchrotron frequency can be obtained. Test calculations were done using simulation data where longitudinal space charge effects were included. The incoherent frequencies obtained with method are in a good agreement with theory. In real experiment, the incoherent frequencies were determined from bunch profiles recorded in the SIS18 with low intensity beam at injection energy. Bunch profiles were measured with a new Fast Current Transformer which has a relatively broad frequency range. The profiles were recorded using 8 bit resolution oscilloscope. The frequency spectra of local current fluctuation at different longitudinal positions were obtained numerically. The strongest lines in these spectra were at positions of theoretically expected incoherent frequencies. In this paper the method is described in details, the comparison of incoherent frequencies obtained from the simulation and measurement data with theoretical solutions is shown.

MOP205	Intense Heavy-Ion Bunches in Dual-harmonic RF Systems	51
	M. Mehler, O. Chorniy GSI, Darmstadt, Germany O. Boine-Frankenheim TEMF, TU Darmstadt, Darmstadt, Germany O.K. Kester IAP, Frankfurt am Main, Germany
	For the synchrotron's SIS-18 and SIS-100 (FAIR) a dual-harmonic RF system with the harmonic numbers h1=2, h2=4 and h1=10, h2=20 respectively is planned. Such systems flatten the bunch form and increase the bunching factor Bf therefore reducing the transverse space charge force. For high currents cavity beam loading and potential-well distortion will deform the flattened bunch shape and lead to phase shifts. Optimized settings for the difference between the two RF phases and for the synchronous phase of the main RF harmonic are an option to reduce these effects. In this contribution we will analyse further aspects of the matched bunch distribution, possible instabilities of the obtained distribution will be discussed and results of machine experiments in SIS-18 will be presented.

TUO1C05	Measurements and Interpretation of the Betatron Tune Spectra of High Intensity Bunched Beam at SIS-18	310
	R. Singh, O. Chorniy, P. Forck, R. Haseitl, W. Kaufmann, P. Kowina, K. Lang GSI, Darmstadt, Germany O. Boine-Frankenheim, R. Singh, T. Weiland TEMF, TU Darmstadt, Darmstadt, Germany
	The paper presents the status of the transverse tune measurements in the synchrotron SIS18 at GSI. Presently, there are two systems for tune measurements in operation in the SIS18, namely TOPOS (Tune, Orbit and POsition measurement System) and BBQ (Base Band tune measurement system). The first one is a digital system where the BPM signal is digitized and the bunch position is calculated numerically. The second system is an analog system, where the transverse bunch motion is detected using peak detector. Band limited noise and chirp excitations were used to excite the betatron oscillations. Measurements of the betatron tune spectra were done at injection energy at medium and high intensities. In the frequency spectra a number of peaks around the position of betatron tune were seen. The peaks can be attributed to different bunch head-tail modes which were observed in time domain. These modes were dependent on the beam intensity. In this paper we compare the tune spectra measured at high beam intensity with the theoretical model for the space charge affected head-tail modes.
	Slides TUO1C05 [1.315 MB]