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

and yellow areas indicate that a similar amount of power is deposited
on both conductors and thus the double-sided scenario dominates.
G
100
90
80
70
60
50
40
30
20
10
0.2 0.4 0.6 0.8 1 1.2 1.4 1.6
Z/Z (Z =50 Ω)
0 0
Figure 5.9: Ratio of power deposited on the inner and outer conductors due
to electron impacts, logarithmic scale log 10(Pinner/Pouter). The
same parameters are used as in Fig. 5.8.
Since the theoretically obtained points agree in general with the PICsimulations,
this confirms the validity of the scaling laws, Eqs. (5.19) and
(5.20). The two different types of modes for single-sided discharge, one
with a phase α ≈ 0 and the other with α ≈ π/4 can also be seen. The
former type of mode is discontinued before reaching the first dashed line
from the right hand side and the latter before the other dashed line in
Fig. 5.7. This is also evident in the PIC-data, especially for values of G
between 30 and 40 in Fig. 5.9 where they are fairly well separated and
only the lower of the paired bands extend into the region between the
dashed lines, as predicted.
In Figs. 5.8 and 5.9 the multipactor threshold can not be identified,
since the oscillatory velocity is kept constant. In Figs. 5.10 and 5.11,
however, the oscillatory velocity has been swept for different G-values
while keeping the ratio Ri/Ro constant and equal to 0.7, i.e. Z = 21.4 Ω
(Z/Z0 = 0.428). Each figure is produced for a different maximum SEY.
When σse,max is low, the ability to compensate for losses is weak and the
zones are well defined and fairly narrow (cf. Fig. 5.10). With increasing
1
0.5
0
−0.5
−1
−1.5
−2
−2.5
85