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

Chapter 6
Detection of multipactor
In the space industry, where multipactor is a well-known problem, great
care is taken to avoid the phenomenon. According to the ESA standard
on multipactor design and test [50] only single carrier parts with a
margin of 8-12 dB (depending on the type of component) in the analysis
stage are exempt from testing. The recommended corresponding margin
for multicarrier parts is 6 dB between the peak power of the multicarrier
signal and the single carrier threshold. By performing unit acceptance
tests, the margins can be reduced to 3-4 dB in the single carrier case
and to 0 dB in the multicarrier case. In order to take advantage of the
smaller margins, accurate and reliable testing is required to verify that
the prescribed margins are actually fulfilled and successful testing relies
on accurate and unambiguous methods of detection.
This chapter starts by briefly reviewing some of the most common
methods of multipactor detection. Then a method of detection is presented,
which can be used in combination with other methods to achieve
accurate and unambiguous test results. Beginning with the single carrier
case, a theory for the underlying mechanism making the method possible
is given together with some supporting data. This is followed by a
discussion outlining how the method can be applied also in the multicarrier
case. Detection of multipactor using RF power modulation, which
is the main topic of this chapter, was analysed in paper A of this thesis.
6.1 Common Methods of Detection
There are several different ways of detecting multipactor and they can be
divided into two fairly distinct categories, viz. global and local methods
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