IPAC2011 - List of Authors (Franchetti, G.)

Paper	Title	Page
MOPS001	Electron-cloud Pinch Dynamics in Presence of Lattice Magnet Fields	586
	G. Franchetti GSI, Darmstadt, Germany F. Zimmermann CERN, Geneva, Switzerland
	The pinch of the electron cloud due to a passing proton bunch was extensively studied in a field free region and in a dipolar magnetic field. For the latter study, a strong field approximation helped to formulate the equations of motion and to understand the complex electron pinch dynamics, which exhibited some similarities with the field-free situation. Here we extend the analysis to the case of electron pinch in quadrupoles and in sextupoles. We discuss the limits of validity for the strong field approximation and we evaluate the relative magnitude of the peak tune shift along the bunch expected for the different fields.

MOPS002	Mitigation of Space Charge and Nonlinear Resonance Induced Beam Loss in SIS100	589
	G. Franchetti GSI, Darmstadt, Germany
	The control of beam loss in SIS100 is essential for avoiding vacuum instability and guarantee the delivery of the foreseen beam intensity. On the other hand simulations show that the simultaneous presence of space charge and lattice resonances creates during 1 second cycle a progressive beam loss exceeding the limit of 5%. Until now the mechanism of periodic resonance crossing were suspected to be, in conjunction with pure dynamic aperture effects, at the base of the beam loss. In this proceeding we present the state of the art in the beam loss prediction and we prove that the periodic resonance crossing is the deteriorating mechanism, and show that the compensation of a relevant resonance intercepting the space charge tune spread sensibly mitigate the beam loss. A short discussion on beam loss during acceleration is addressed as well.

WEPC057	Estimation of the Dynamic Aperture by Transverse Beam Excitation with Noise Close to a Resonance	2145
	S. Sorge, G. Franchetti GSI, Darmstadt, Germany
	The present heavy ion synchrotron SIS-18 will be upgraded to be used as a booster for further synchrotrons being part of the FAIR project underway at GSI. Recently, a method was developed to measure the physical aperture of SIS-18 using transverse RF noise. This method is based on the transverse expansion of the beam with noise beyond the limiting aperture generating beam loss. The aperture was determined from the comparison of the resulting time evolution of the beam current in the machine with that obtained from a numerical simulation. In this study we attempt to apply this method to determine the dynamic aperture of SIS-18.

WEPC091	Studies with a Particle Tracking Code for the SIS100 Resonant Extraction System	2220
	M.M. Kirk, G. Franchetti, H. Klingbeil, P. Moritz, N. Pyka, H. Ramakers, P.J. Spiller, H. Welker GSI, Darmstadt, Germany
	Several issues concerning the envisaged SIS100 resonant extraction at GSI can be resolved with a simulation-lead approach for which a particle tracking code was developed. Applications to date have included: design and testing of data supply algorithms for the accelerator control system; requirements analysis for the power converter ripple in the quadrupoles forming the doublet focusing; and verification of the RF Knock-Out exciter's performance.

Paper

Title

Page

Electron-cloud Pinch Dynamics in Presence of Lattice Magnet Fields

586

G. Franchetti
GSI, Darmstadt, Germany
F. Zimmermann
CERN, Geneva, Switzerland

The pinch of the electron cloud due to a passing proton bunch was extensively studied in a field free region and in a dipolar magnetic field. For the latter study, a strong field approximation helped to formulate the equations of motion and to understand the complex electron pinch dynamics, which exhibited some similarities with the field-free situation. Here we extend the analysis to the case of electron pinch in quadrupoles and in sextupoles. We discuss the limits of validity for the strong field approximation and we evaluate the relative magnitude of the peak tune shift along the bunch expected for the different fields.

MOPS002

Mitigation of Space Charge and Nonlinear Resonance Induced Beam Loss in SIS100

589

G. Franchetti
GSI, Darmstadt, Germany

The control of beam loss in SIS100 is essential for avoiding vacuum instability and guarantee the delivery of the foreseen beam intensity. On the other hand simulations show that the simultaneous presence of space charge and lattice resonances creates during 1 second cycle a progressive beam loss exceeding the limit of 5%. Until now the mechanism of periodic resonance crossing were suspected to be, in conjunction with pure dynamic aperture effects, at the base of the beam loss. In this proceeding we present the state of the art in the beam loss prediction and we prove that the periodic resonance crossing is the deteriorating mechanism, and show that the compensation of a relevant resonance intercepting the space charge tune spread sensibly mitigate the beam loss. A short discussion on beam loss during acceleration is addressed as well.

WEPC057

Estimation of the Dynamic Aperture by Transverse Beam Excitation with Noise Close to a Resonance

2145

S. Sorge, G. Franchetti
GSI, Darmstadt, Germany

The present heavy ion synchrotron SIS-18 will be upgraded to be used as a booster for further synchrotrons being part of the FAIR project underway at GSI. Recently, a method was developed to measure the physical aperture of SIS-18 using transverse RF noise. This method is based on the transverse expansion of the beam with noise beyond the limiting aperture generating beam loss. The aperture was determined from the comparison of the resulting time evolution of the beam current in the machine with that obtained from a numerical simulation. In this study we attempt to apply this method to determine the dynamic aperture of SIS-18.

WEPC091

Studies with a Particle Tracking Code for the SIS100 Resonant Extraction System

2220

M.M. Kirk, G. Franchetti, H. Klingbeil, P. Moritz, N. Pyka, H. Ramakers, P.J. Spiller, H. Welker
GSI, Darmstadt, Germany

Several issues concerning the envisaged SIS100 resonant extraction at GSI can be resolved with a simulation-lead approach for which a particle tracking code was developed. Applications to date have included: design and testing of data supply algorithms for the accelerator control system; requirements analysis for the power converter ripple in the quadrupoles forming the doublet focusing; and verification of the RF Knock-Out exciter's performance.