Cirrus SP101013.111 – 10 October 2012
MKS Instruments UK Ltd., Spectra Products
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Setting the UDV - Basics
The UDV’s manual valve is opened to allow a pressure of 10x the required ion-source pressure, the
desired ion-source pressure is then maintained electronically by the UDV controller.
As an ion-source pressure of 5mTorr is required, open the manual valve until the voltmeter indicates
6.7V (approx 0.067 mBar). This is 10x the desired pressure.
Switch on the RGA’s filaments and run a Bar Chart recipe, masses 1 – 50.
Now we need to adjust the amount of current needed to fully close the valve. This process takes some
time and is a critical adjustment. Simply turning the “Limit” adjustment to full current would be the
same as over tightening a manual valve.
Set the switch indicated to the “Limit” position.
Slowly adjust the “Limit” control, while watching the “Valve Current” display, making sure that the
current does not rise into the hatched area.
An easy indication of the full closure of the valve is to keep an eye on the Air peak and the voltmeter.
Once the air peak has decreased to the base-line and the voltmeter reads zero, we can assume the
valve is closed.
Note:
You may find that you have to increase voltage slightly negative of zero for the air peak to
disappear completely, if the value is small (1-5mV) then continue the set-up. If the voltage is 5mV+,
then ensure the manual valve is fully closed and re-zero the Baratron before moving on.
Switch back to “Set Point”
