78
I. E. Ivanov et al.
Table 6.1 Parameters of the Hagena theory
Coefficient of accommodation β
g
n
r arg (m)
α
0.2
2.5
0.23 × 10 17
0.72 × 10 −7
0.1984
0.1
2.0
2.603 × 10 17
0.325 × 10 −7
0.2054
0.1
1.6
5.93 × 10 17
0.251 × 10 −7
0.2143
0.1
1.325
9.096 × 10 17
0.2198 × 10 −7
0.2178
N = b
∗
1000
(6.34)
For argon, Eqs. 6.35 and 6.36 are applicable, where ϕ is nozzle expansion angle,
d ∗ = 750 mkm, p 0 = 20, 000 mbar, T o = 295 K, r avrg =
Nm
4 / 3πρ
, m = 6.63 ×
10
−26 kg, b = 100, a = 1.8.
∗
= 1650P 0 d
0.85
eq T
2.29
0
(6.35)
d eq = 0.736d ∗
tan ϕ
(6.36)
The results of the nozzle under consideration for the Hagena’s theory are the
following: N = 7.3 × 10
5 , r avrg = 0.21 × 10
−7 m, n = 9.2 × 10
17 1/m
3 .
Table 6.1 shows the dependence of the parameters obtained at the nozzle exit on
the accommodation coefficient and the parameter g.
The best approximation was achieved using the parameter values β = 0.1, g =
1.325.
6.4 Results
The numerical study of the processes occurring in the device of generating cluster
beams is carried out. At this stage, the operating modes of the device corresponding to
incomplete pumping of gas from the vacuum chamber are considered. The behavior
of clusters at the shock wave in front of the skimmer and their further development
in the inner region of the skimmer is the subject of interest. The geometry, grid, and
boundary conditions of the computational domain are discussed in Sects. 6.4.1–6.4.3,
respectively. Section 6.4.4 contains the results of the calculations.
I. E. Ivanov et al.
Table 6.1 Parameters of the Hagena theory
Coefficient of accommodation β
g
n
r arg (m)
α
0.2
2.5
0.23 × 10 17
0.72 × 10 −7
0.1984
0.1
2.0
2.603 × 10 17
0.325 × 10 −7
0.2054
0.1
1.6
5.93 × 10 17
0.251 × 10 −7
0.2143
0.1
1.325
9.096 × 10 17
0.2198 × 10 −7
0.2178
N = b
∗
1000
(6.34)
For argon, Eqs. 6.35 and 6.36 are applicable, where ϕ is nozzle expansion angle,
d ∗ = 750 mkm, p 0 = 20, 000 mbar, T o = 295 K, r avrg =
Nm
4 / 3πρ
, m = 6.63 ×
10
−26 kg, b = 100, a = 1.8.
∗
= 1650P 0 d
0.85
eq T
2.29
0
(6.35)
d eq = 0.736d ∗
tan ϕ
(6.36)
The results of the nozzle under consideration for the Hagena’s theory are the
following: N = 7.3 × 10
5 , r avrg = 0.21 × 10
−7 m, n = 9.2 × 10
17 1/m
3 .
Table 6.1 shows the dependence of the parameters obtained at the nozzle exit on
the accommodation coefficient and the parameter g.
The best approximation was achieved using the parameter values β = 0.1, g =
1.325.
6.4 Results
The numerical study of the processes occurring in the device of generating cluster
beams is carried out. At this stage, the operating modes of the device corresponding to
incomplete pumping of gas from the vacuum chamber are considered. The behavior
of clusters at the shock wave in front of the skimmer and their further development
in the inner region of the skimmer is the subject of interest. The geometry, grid, and
boundary conditions of the computational domain are discussed in Sects. 6.4.1–6.4.3,
respectively. Section 6.4.4 contains the results of the calculations.