70
3 CI Troubleshooting
Pressure-Related Symptoms
The following symptoms are all related to high vacuum pressure. Each
symptom is discussed in more detail in the following pages.
The mass flow controller is calibrated for methane, and the high vacuum gauge
controller is calibrated for nitrogen, so these measurements are not accurate
in absolute terms (Table 8). They are intended as a guide to typical observed
readings. They were taken with the following set of conditions:
Source temperature 250 °C
Quad temperature 150 °C
Interface temperature 280 °C
Helium carrier gas flow 1 mL/min
Tab le 8 Pressure measurements
Pressure (Torr)
MFC (%) Methane Ammonia
10 5.5 × 10
–5
5.0 × 10
–5
15 8.0 × 10
–5
7.0 × 10
–5
20 1.0 × 10
–4
8.5 × 10
–5
25 1.2 × 10
–4
1.0 × 10
–4
30 1.5 × 10
–4
1.2 × 10
–4
35 2.0 × 10
–4
1.5 × 10
–4
40 2.5 × 10
–4
2.0 × 10
–4
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