next up previous
Next: Sweeping of the HOM Up: General Features Previous: Bunch Form Factor

Shifting of the HOM Frequencies to the Closest Dangerous Resonant Frequency

A monopole HOM impedance can contribute the maximum growth rate to a symmetric longitudinal mode when the HOM frequency happen to fall on a revolution harmonic upper synchrotron sideband. Similarly, a dipole HOM impedance can contribute the maximum growth rate to a symmetric transverse mode when the HOM frequency happen to fall on a revolution harmonic lower betatron sideband. An optional data column may be included in the HOM definition file (see section 4) to force selected HOM frequencies onto dangerous resonances. Because of the relatively low probability for HOM frequencies to hold exactly these resonant values, this option is mostly useful in checking the calculated growth rates against those obtained in hand calulations.



Randy Flood 2006-11-06