VivekKamble
Ansys Employee

Hello,

Mainly there can be four cases where multipaction can occur.

1. If free electrons are available to start the release of secondary electrons.

2. If the mean free path of the electrons is greater than the spacing between the surfaces opposite to each other (no obstruction should be present in the way).

3. If the average number of electrons released is greater than the electrons yielded secondarily on the surface. This is dependent on the RF field strength between the plates. 

4. If the time taken by the electron to travel from the surface on which it got created to the surface with which it will impacts, is an integer multiple of half the RF period.

Hope that addressed your query!