Poor Sensitivity With Ei Source; Poor Sensitivity With Ci Source - Waters Xevo TQ-GC Overview And Maintenance Manual

Table 6–2: Unstable or low-intensity ion beam (continued)
Possible causes
Unsuitable lens settings.
Old and inefficient filament.
Dirty ion repeller or ionization chamber.
No reference gas.

6.2.3 Poor sensitivity with EI source

The following table lists the possible causes and corrective actions for this problem.
Table 6–3: Poor sensitivity with EI source
Possible causes
Inefficient or sagging filament.
Dirty ion repeller or ionization chamber.
The EI filament yttrium oxide coating has worn
away.
OR
CI filament (not yttrium oxide coated) fitted.

6.2.4 Poor sensitivity with CI source

The following table lists the possible causes and corrective actions for this problem.
Table 6–4: Poor sensitivity with CI source
Possible causes
Inefficient or sagging filament.
Partially blocked entrance hole.
April 27, 2020, 715005564 Ver. 01 (previously released as Rev. A)
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Corrective actions
Verify the lens settings and readbacks.
Ensure that all settings affect the beam.
High filament current for a given emission.
Replace the filament.
A high repeller voltage (50 V) is needed to
maintain sensitivity.
Clean the repeller and the ionization chamber.
Refill the reference gas ampule.
Corrective actions
Replace or reposition the filament.
A high repeller voltage (50 V) is needed to
maintain sensitivity.
Clean the repeller and the ionization chamber.
The yttrium oxide coating is necessary to
reduce the operating temperature of the
filament, extending the filament lifetime.
If there is no yttrium oxide coating, replace the
filament with another EI filament.
Corrective actions
Replace or reposition the filament.
Clean the inner source.