Degas
Degassing the crossbeam ion source is only recommended in exceptional cases.
● Pressure: ≤ 10
-8
hPa
● Emission: ≤ 10 mA (at 550 V)
● Time: ≤ 5 minutes
100 V
-100 V
0
V
1
V
5
V
3
V
4
V
2
1 2 3
4
5
6
7
8
Fig. 3:
Electrode arrangement and potential curve of the crossbeam ion source
1 Wehnelt
5
Base plate
2 Cathode
6
Focus
3 Ionization area
7
Entrance orifice
4 Extraction
8
Rod system
Emission
1 mA
4)
V1
Ion Reference
90 V
V2
Cathode
70 eV
5)
V3
Focus
20 V
V4
Field Axis
15 V
V5
Extraction
250 V
V6
Inner Deflection
300 V
Protection Current
W
YO
x
-Ir
4.2 A
3.5 A
Tbl. 4:
Typical values of the crossbeam ion source
3.2.3 Grid ion source
The grid ion source has a very open design, has an extremely low outgassing rate and can be de-
gassed easily. It emits only a few surface ions. It is always equipped with two tungsten filaments.
4)
With magnet 0.7 mA / At p > 5 × 10
-6
hPa, reduce to 0.1 mA.
5)
Before reducing V2 to < 50 eV, reduce the "Emission" to 0.1 mA and V9 to < 20 V to prevent overloading of
the cathode.
Product description
19/52
