**2.4 Other effects**

#### *2.4.1 Multipaction and corona discharge*

*Multipaction* is, basically, an event that can be reason of breakdown because of high power RF signal in a vacuum or near vacuum medium. It can reduce RF output power of device, cause noise in RF signal and even *corona discharge* because of ionization in presence of electromagnetic wave. Therefore, it can result a catastrophic failure of an antenna, RF component and even another payload module. There are two main factors for multipaction: high RF power and vacuum medium. Thus, related RF components including antennas should be either analyzed or tested for these phenomena. There is an analysis tool designed by ESA/ESTEC named as "ECSS Multipactor Tool". By using this tool one can calculate threshold and safety margin levels for pre-defined structures according to the operating frequency, impedance, RF power level, material finishing and minimum distance between metal tips or edges.
