Study of non-linear effects of a resonant cavity on the longitudinal dynamics of a costing particle beam
1975; Elsevier BV; Volume: 128; Issue: 2 Linguagem: Inglês
10.1016/0029-554x(75)90670-9
ISSN1878-3759
AutoresEberhard Keil, Ernst Messerschmid,
Tópico(s)Gyrotron and Vacuum Electronics Research
ResumoA computational method has been developed to stimulate the longitudinal motion of a relativistic beam charged particles circulating in a strong focusing method has been synchrotron or storage ring. Unlike most analytical approaches the stimulation is not restricted to small pertubations and thus the growth of instabilities can be followed into the non-linear region. The investigations show that, as a result of an instability, the final energy spread of an initially unbunched beam interacting with a resonant cavity is larger than the vale at threshold and tends to a limit which depends on both the initial energy spread and on the spread at threshold. Although the cavity has a high impedanceonly at the revolution frequency of the beam, the particle distributions contain Fourier components at multiples of the revolution frequency. The growth rate and threshold agree well with those obtained from linear theory, if the cavity filling time is small compared to the growth time of the instability, and if the frequency spread within the beam is small compared to the width of the cavity resonance. If the first condition does not hold, the growth time becomes longer; and a frequency spread within the beam larger than the width of the cavity resonance results in a slight reduction of the threshold spread, and the overshoot of the final energy spread over this spread becomes smaller.
Referência(s)