Resistive wall impedance is the main cause of instabilities in synchrotrons and storage rings. The real part of the dipolar transverse coupling impedance can drive transverse beam instabilities. For SIS18 as well as in the planned SIS100, the resistive part of the transverse Koppel impedance is dominated by the beam tube at low frequencies.
To reduce eddy current effects during the magnetic ramp, the SIS100 beamline will be very thin. Due to mechanical and vacuum reasons, the SIS100 beamline will be built with stabilising struts and cooling tubes. For such complicated structures, the coupling impedance can no longer be determined analytically, but must be calculated with numerical 3D electromagnetic frequency-domain simulations. For calculating the coupling impedance of accelerator elements, the software CST Particle Studio can be used, for example. However, the department also develops its own tools for calculating beam coupling impedances in the frequency domain. We will be happy to provide you with some of these tools; please contact us personally!