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Tesi etd-09052006-141047

Thesis type
Tesi di laurea specialistica
Falbo, Luciano
email address
Longitudinal beam dynamics in SRFF regime
Corso di studi
Relatore Biscari, Caterina
Relatore Prof. Cervelli, Franco
Parole chiave
  • beam
  • dynamics
  • SRFF
Data inizio appello
Riassunto analitico
Obtaining short bunch is a very important issue for modern accelerators, especially for colliders and coherent <br>synchrotron radiation (CSR) sources; however the coherent instabilities pose strong limitations on the bunch length and <br>on the current stored in the bunch at a given length.<br> In all the present storage rings <br>the bunch has the same length along the ring; <br>the principle of the Strong RF Focusing (SRFF) consits in realizing a lattice in which bunch length is not constant and we have the so<br>called bunch length modulation. An experiment at DA$\Phi$NE, the Frascati $\Phi-$factory, has been proposed, in order to<br>test, for the first time, this idea. <br>The subject of this work is the study of the longitudinal single bunch dynamics in the regime of Strong RF focusing. <br>In fact,<br>until now, the principle of bunch length modulation <br>has been studied only from the optical point of view, i.e. without considering the effects of the impedances that pose limitations <br>to the maximum <br>current storable. <br><br>The thesis is organized as follows. <br> In the first chapter I present <br>the physical interest of DA$\Phi$NE collider; in particular, since in a collider the maximum luminosity is<br> related to bunch length, I show the physical advantages to increase the DA$\Phi$NE luminosity.<br>In the second chapter the present status of DA$\Phi$NE lattice is presented.<br>In the next two chapters the problem of the coherent instabilities is analysed in the DA$\Phi$NE case, by considering <br> the interaction of the beam with the vacuum chamber and the effects of the CSR on beam <br>dynamics.<br>In the following chapter the principle of SRFF is reported, in particular it is decsribed the possibility<br>to test it at DA$\Phi$NE realizing different lattices able <br> to analyse the different aspects and properties of this new regime<br>In the sixth chapter I describe the C code SPIDER (Simulation Program for Impedances Distributed along Electron Rings) <br>I wrote in order to study the relation between bunch length and current stored in a regime of bunch length <br>modulation. The code, in fact, allows to consider the effect of the impedance of a specific structure of the machine<br>on longitudinal bunch distribution in the structure itself. Therefore, even if the code is able to simulate the behaviour of bunch<br>length of existent machines (it was successfully applied to the present status of DA$\Phi$NE), it is the only code able to<br>study the effect of longitudinal bunch stability in a regime of bunch length modulation. <br>Finally, in the last chapter, there are the results of the simulations made by the application of the code SPIDER to the three<br>lattices presented in the fifth chapter.<br><br><br>