Multipactor in Low Pressure Gas and in ... - of Richard Udiljak

can be said that there are three main effects that affect the low pressure
multipactor threshold. The friction force tends to increase the threshold
as a higher electric field is needed to reach the necessary impact velocity.
The thermalisation, on the other hand, increases the total impact energy
and thus a lower electric field is needed to achieve the required impact
velocity. For materials with a low first cross-over point, the first effect
dominates for the first order of resonance, while for higher order modes,
the latter plays the main role. In addition to these two effects, the model
also includes contribution from impact ionisation to the total number
of electrons. This addition also tend to lower the multipactor threshold
and the effect becomes very prominent for materials with a high first
cross-over energy as a consequence of the concomitant high ionisation
cross-section.
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