Transverse Schottky spectra and beam transfer functions of coasting ion beams with space charge.
Technische Universität, Darmstadt
[Ph.D. Thesis], (2010)
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|Item Type:||Ph.D. Thesis|
|Title:||Transverse Schottky spectra and beam transfer functions of coasting ion beams with space charge|
A study of the transverse dynamics of coasting ion beams with moderate space charge is presented in this work. From the dispersion relation with linear space charge, an analytic model describing the impact of space charge on transverse beam transfer functions (BTFs) and the stability limits of a beam is derived. The dielectric function obtained in this way is employed to describe the transverse Schottky spectra with linear space charge as well. The difference between the action of space charge and impedances is highlighted. The setup and the results of an experiment performed in the heavy ion synchrotron SIS-18 at GSI to detect space-charge effects at different beam intensities are explicated. The measured transverse Schottky spectra and BTFs are compared with the linear space-charge model. The stability diagrams constructed from the BTFs are presented. The space-charge parameters evaluated from the Schottky and BTF measurements are compared with estimations based on measured beam parameters. The impact of collective effects on the Schottky and BTF diagnostics is also investigated through numerical simulations. For this purpose the self-field of beams with linear and non-linear transverse density-distributions is computed on a two-dimensional grid. The noise of the random particle distribution causes fluctuations of the dipole moment of the beam which produce the Schottky spectrum. BTFs are simulated by exciting the beam with transverse kicks. The simulation results are used to verify the space-charge model.
|Place of Publication:||Darmstadt|
|Uncontrolled Keywords:||space charge, Schottky noise, transverse beam transfer functions, collective effects, coasting ion beams, PhD thesis|
|Classification DDC:||500 Naturwissenschaften und Mathematik > 530 Physik
600 Technik, Medizin, angewandte Wissenschaften > 620 Ingenieurwissenschaften
|Divisions:||18 Fachbereich Elektrotechnik und Informationstechnik|
|Date Deposited:||27 Apr 2010 10:04|
|Last Modified:||07 Dec 2012 11:57|
|Referees:||Weiland, Prof. Dr.- Thomas and Boine-Frankenheim, Prof. Dr. Oliver and Pietralla, Prof. Dr. Norbert Andreas|
|Refereed:||2 February 2010|