39 300781172_002_C0 - 01/2019 - © Leybold
Cautions in operation
4. Calculate the ratio of (2) to (3), that is "(2)/(3)", to give the amplification factor of
SEM and check the condition of deterioration.
For example:
Measurement value of SEM = 9.71e-5A, measurement value of FC = 6.12e-11A
9.71 x 10
-6
A / 6.12 x 10
-11
A = 1.59 x 10
5
The multiplication factor of SEM is 159000 times.
9.4 Baking
If the analyzer tube is left under atmospheric pressure for an extended time and
contaminated, carry out baking (heating) to remove contamination and reduce the
out-gassing of the Residual Gas Analyzer (background).
The LEYSPEC view models can be heated up to 120 °C with the sensor unit
connected, up to 250 °C without the sensor unit connected.
The LEYSPEC ultra models can be heated up to 250 °C with the sensor unit
connected, up to 300 °C without the sensor unit connected.
9.4.1 Baking procedure (with removal of sensor unit)
1. Make sure that there are no leaks and check that the pressure is 1 x 10
-4
Pa or
less before baking.
2. Turn off the sensor unit’s power and remove the sensor unit.
3. LEYSPEC ultra p the analyzer tube with aluminium foil to improve heat
conduction.
4. Wind the baking heater around the analyzer tube.
5. Wind aluminium foil around the baking heater.
6. The temperature and time of baking depend on conditions. As a guide, bake at
around 150 °C for 12 hours. Always control the temperature using a thermocouple
or similar so that the analyzer tube will not be damaged by excessive temperature
rises.
CAUTION:
Conduct baking at a pressure of 1 x 10-4 Pa or less. If it is conducted in a higher
pressure region, the sensor head will be contaminated.
CAUTION:
Risk of damage to the sensor unit. Do not connect or disconnect the cable with
the power turned on.
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