Author: Haenichen, L.     [Hänichen, L.]
Paper Title Page
MOPS052 Analytical and Numerical Calculations of Beam Pipe Impedances at Low Frequencies with Application to Thin SIS100 Pipe 721
 
  • U. Niedermayer, O. Boine-Frankenheim, L. Hänichen
    TEMF, TU Darmstadt, Darmstadt, Germany
 
  The projected fast ramped synchrotron SIS100 for FAIR uses an elliptical stainless steel beam pipe of 0.3 mm thickness. The lowest coherent betatron sidebands reach down to 100 kHz which demands accurate impedance calculations in the low frequency (LF) regime. For these frequencies, i.e. skin depth greater than wall thickness, structures behind the pipe may contribute to the impedance. Due to the extremely large wake length numerical methods in the time domain are not applicable. The longitudinal and transverse impedance of the thin SIS100 beam pipe including structures behind the pipe are obtained numerically by a method using power loss in the frequency domain. We compare different analytical models for simplified pipe structures to the numerical results. The dc and ultra-relativistic limits are investigated. The interpretation of bench measurements in the LF regime is discussed.