The eSeminar will show the general approach to simulate multipaction and breakdown analysis with CST Studio Suite®. Since multipaction is an effect dominated by the particle movement of secondary electrons, this is addressed by means of the PIC code of CST PARTICLE STUDIO®. The breakdown analysis is more a plasma effect and will be analyzed with CST MICROWAVE STUDIO® using a non-linear Drude model. Different examples such as filters, diplexer or simple coaxial cable are used to illustrate the functionality. Some special aspects such as saturation of particles, distortion of signals, usage of arbitrary time signals or alternative detection criterion will be addressed as well. Last but not least, the link to SPARK3D from Aurorasat will be shown.