The Tune window tuning controls B-27
Source Temperature The temperature of the source in °C is normally
set at 100 to 150 °C, which suits most samples.
Using a lower temperature may reduce fragmen-
tation. However, this is likely to allow compounds
with a high boiling point to condense in the
source, which can reduces sensitivity over time.
Note: A readback of 503 indicates that the source
heater is disconnected.
See also: EI/CI inner source maintenance on
page 10-18.
Electron Energy The voltage between the filament and the source.
This parameter is set to a default value of 70.
See also: .Figure titled “Electron impact ioniza-
tion:” on page G-4.
Filament Current The current passing through the filament is
normally between 2 and 4 A in CI.
Emission Current A measurement of the number of electrons
emitted by the filament. The default value is
200 µA.
Tip: There is no trap in the CI source.
See also: Chemical ionization on page G-4.
Limit Rhenium Filament
Current
When selected this parameter limits the current
to a default maximum value of 3.6 A, which
prevents damage to the Rhenium filament if it is
accidently inserted into the source in EI mode.
Note: If for some reason you fit a tungsten fila-
ment on the CI source, ensure that this check box
is cleared.
Caution: To prevent damage to the rhenium fila-
ment, select the check box.
CI Tune tab parameters: (Continued)
Parameter Description
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