Probably each isotoper faced with such problem. Some advices from my
1.First check the area where last time you did something - visually check all
wires, electrodes, screws. Probably you have some unwanted contact. Test all
ion source pins on connector side with tester for unwanted contacts .
2. In critical situations after the ion source had been installed and pumped
down I checked all pins again with insulator tester for 500 volts. It helps to
find even some leaks on insulator surfaces.
3. Each new installed filament I train in order: turn off emission - turn on
ion source - during 2 or 3 hours step by step increase emission with
4. Power supply of filament can be checked with some radio lamp - find
schematic of the lamp and connect mass spec filament wires with the lamp
filament pins. If you can regulate brightness of the lamp filament - your
electronics is ok.
>===== Original Message From Stable Isotope Geochemistry
<[log in to unmask]> =====
>We are having some trouble with our dual inlet delta plus, and thought
>might have some suggestions as to what the problem may be. Here's what has
>happened. The instrument had been running fine with no problems for several
>months (it has been running deuterium on water via a Finnigan H/device), then
the source filament went out. So we took out the source, replaced the
filament and put it back in. Pumped down the source overnight, then turned on
the HV in the morning. Emission came on and filament blew out within minutes.
So now same thing...replaced the filament, pumped down overnight, and flipped
on the HV. We had emission (light was on) but we had zero intensity when we
would open gas to the source. We have tried it with H and CO2 gas and neither
gave us any voltage. We also tried it from both the reference and sample
sides and were confident that gas was getting to the source. It's almost as
if no ions were being created. When we came in the next morning we found that
the new filament had also blown out. We lost two filaments in as many days.
Both were Finnigan filaments (which we've always used) bought at the same
time. Any ideas as to what the problem could be? Is it possible !
> that there is a bad batch of filaments? Or possibly some problem with an
electrical board? Any help would be greatly appreciated as we are at a
complete loss. Thanks so much!
>University of Washington
>Stable Isotope Lab
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Sergey OLEYNIK, PhD
Ecology and Evolution
Dept. Biological Sciences
University of Illinois, Chicago
845 W. Taylor st.
UIC, 3342 SES
Chicago, IL 60607
Phone: office 312-9964584
lab 312-3550600 (voice)
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