SRS Labs QMS 100 Series, Руководство пользователя

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Display Modes 2-15
SRS QMS Gas Analyzer
Scanning With The Filament Off
The software can run experiments with the filament off. This is useful only to researchers who
perform experiments that generate their own source of ions.
The program will warn you if you start a scan without the filament turned on. This is done to
prevent casual use and accidents. However advanced users who are going to use this mode
frequently can disable the warning in the ionizer settings for a particular Rga Head, or just check
the box "never ask me again" in the warning dialog.
Note: Using this mode presents some risk to the RGA hardware
With the filament off, the RGA has no method to detect total pressure. If the CEM is on, the
RGA will not be able to detect a high pressure condition and will not automatically turn off the
CEM. Without this protection, it is possible for the pressure to reach a level where a sustained
electrical discharge will occur from the CEM to the surrounding wall.
Warning: The CEM will be destroyed by such a discharge.
The most likely situation during which this can occur is when shutting down a vacuum system.
As the chamber is slowly vented, the pressure will reach the discharge region. Do not leave the
RGA with the CEM on when a system is being shut down. Better yet, do not leave the RGA on
at all when the vacuum chamber is being shut down.
This can also occur when power failures trip out the turbo pump of the vacuum system. As the
pump coasts to a stop, the pressure rises to the discharge region. If you are going to use the RGA
unattended with the CEM on, consider using an interlock to shut off power to the RGA if the
turbo pump is not running. Many pump controllers have an outlet that is only powered when the
pump is running. Plugging the RGA into this outlet would protect against this failure mode.
Note, with the filament off, the RGA will appear dead to a user who is expecting to run a normal
experiment. The only indication that the filament is off, will be a lack of signal.
Because of these concerns, the "Filament On" mode is always initiated by default. Only a small
number of users need this ability to operate without the filament on, and they must be fully
aware that it is being enabled.
Display Modes
Note: For detailed information and command description of the RGA program please refer
to the RGA On-Line Help files provided on the program CD. The RGA help system
includes detailed description of all the features, procedures and commands available in the
program.