By using the linear kinetic theory and the particle-in-cell code SCOP-RZ/PATRIC the longitudinal instability observed in the ESR has been investigated for different values of the longitudinal impedance of the machine. The numerical investigations show that initially the instability grows exponentially as predicted by the linear theory. When the perturbation reaches large values, significant high-order harmonics are produced: steepening of the density profile as well as saturation of the instability growth appear first, and turbulence later on. Analytical and numerical studies with a small RF voltage applied at the detuned cavity gap have also been carried out in order to meet the conditions in which actual measurements were made at the ESR. (C) 1998 Elsevier Science B.V. All rights reserved.
Comparison between theory and simulations for longitudinal instabilities of coasting beams
MIANO, GIOVANNI;
1998-01-01
Abstract
By using the linear kinetic theory and the particle-in-cell code SCOP-RZ/PATRIC the longitudinal instability observed in the ESR has been investigated for different values of the longitudinal impedance of the machine. The numerical investigations show that initially the instability grows exponentially as predicted by the linear theory. When the perturbation reaches large values, significant high-order harmonics are produced: steepening of the density profile as well as saturation of the instability growth appear first, and turbulence later on. Analytical and numerical studies with a small RF voltage applied at the detuned cavity gap have also been carried out in order to meet the conditions in which actual measurements were made at the ESR. (C) 1998 Elsevier Science B.V. All rights reserved.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
