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

G
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0.2 0.4 0.6 0.8 1
V /V
ω max
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Figure 5.13: Same as Fig. 5.12 only with σse,max = 1.3.
clearly passes this limit (see Fig. 5.14).
5.2.3 Comparison with experiments
As mentioned in the introduction to this chapter, PIC-simulations can
include aspects of the multipactor, which are difficult to analyse theoretically.
As a more realistic description is possible, quantitative comparison
with experiments becomes feasible.
In the experimental study by Woo [63] coaxial lines made of copper
were used. When taking values for the secondary electron emission properties
for copper from the ESA standard [50], the lower thresholds of the
PIC-simulations are not in very good agreement with the experimental
data. However, the secondary emission properties can vary a great deal
between different samples of the same material and contamination can
reduce the first cross-over point and increase the maximum SEY. Thus
by slightly lowering the first cross-over point in the PIC-simulations,
very good agreement is obtained (see Fig. 5.15). In paper F an alternative
method of obtaining the experimental threshold when using the
secondary emission properties given in the ESA standard [50] is presented,
based on a modification of the used model for the SEY [22].
However, this will not be discussed further in this summary.
In the experiments an increase in the multipactor threshold for de-
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