GSI, Darmstadt
TEMF, TU Darmstadt, Darmstadt
To achieve a high current operation close to space charge limit, a precise tune measurement during a full accelerating cycle is required. A tune measurement system was recently commissioned at GSI SIS-18, which allows calculation of tune using digital position data. It consists of three distinct parts; an exciter which provides band limited white noise to excite coherent betatron oscillations in the beam. The fast ADCs digitize the BPM signals at 125MSa/s and the post processing electronics integrate the data bunch by bunch to acquire one position value per bunch. Subsequently base band tune is determined by frequency transformation of the position data. Using this system, the charge effects were studied by correlating the current levels to tune spread/shift in the GSI synchrotron SIS-18. The experiment was conducted at injection energy of 11.6 Mev/nucleon using U73+.
GSI, Darmstadt
As conventional intercepting diagnostics will not withstand high intensity ion beams, the non-destructive Beam Induced Fluorescence (BIF) method for transverse profile monitoring was extensively developed during the last years at the GSI heavy ion facility. An overview of the general performance, technical realization, applications and limitations will be given. Detailed investigations required for the optimization of this method were performed. Fluorescence spectra for various working gases like nitrogen and rare gases were recorded using an imaging spectrograph and wavelength selected beam profiles were obtained. The recorded profile width coincides for all working gases with the exception of He showing a significantly broader beam image. Experiments concerning the background contribution by beam induced neutrons and gammas were performed and the consequences for a possible installation close to a target will be discussed.
GSI, Darmstadt
In this contribution we present the simulations of the experiment made in the SIS18 synchrotron on the effect of the space charge in a bunched beam stored for one second. To the simulations a discussion of the underlying dominant effect (trapping or scattering?) is included. A discussion on the consequences of this beam dynamic regime on the SIS100 is presented, open issues and future (experimental and numerical) studies are outlined.