Application examples
● Residual gas analysis in UHV
● Desorption measurements
Function
The two electrons which are emitted by the ring cathode are accelerated toward the grid and mainly
pass through the grid. The ions formed inside the grid are drawn to the mass filter by the grounded en-
trance orifice. The cathode is connected in the middle; each half of it can thus be operated separately.
Degas
With the degas function, the outgassing rate of the grid ion source and the desorption of surface ions is
reduced.
● Pressure: ≤ 10
-7
hPa
● Emission: ≤ 20 mA (at 550 V)
● Time: 10–15 minutes
Degassing recommendations for the grid ion source
1. Perform degassing for 10 – 15 minutes.
2. Wait for the final pressure.
3. Check the spectrum.
4. Repeat the operation if needed.
100 V
0
V
1
V
2
V
4
1
2
3
4
Fig. 4:
Electrode arrangement and potential curve of the grid ion source
1 Grille
3
Entrance orifice
2 Cathode
4
Rod system
Emission
2 mA
6)
V1
Ion Reference
120 V
V2
Cathode
100 eV
7)
V4
Field Axis
10 V
6)
At p > 5 × 10
-6
hPa, reduce to 0.2 mA.
7)
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
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