Kendra,

I have blow filaments rapidly because the EA was leaking O2 into the He
line, this was going into the MS and oxidizing the filaments.  This might
be a problem, but only after the Cu column is exhausted.  You  could take
out the Cu column and see.

   When you get the system up and running again you might try scanning mass
32 and make sure that it is low at a low voltage, but this will only occur
when the Cu is finished.  My own experience was that the system ran
overnight, then the next morning I had a high mass 32 and then when I
checked the Cu column it was exhausted.  Only a few times like this are
enough to finish the filament.

Hope this helps,

Paul.



At 12:18 PM 10/25/00 -0700, you wrote:
>Hello...
>
>        We've just blown two filaments in two days on our Finnigan
>Delta Plus XL.  The first filament went sometime after running
>approximately 100 zooplankton samples on the EA peripheral (of
>relatively small, consistent size).  There is some evidence that we
>may have had some power fluctuations around this time, and that is
>what I originally thought was the most probable cause.  The first
>filament was just over a year old.
>        We replaced that filament with the only one we had on
>hand...one that was in good condition but had been in the instrument
>previously (for approx. 6 months).  In the end we had to solder the
>Ag leads to increase their strength, but it was successfully
>installed.  After reaching good vacuum, the source was turned on, and
>we performed a BSCAN.  The results were satisfying, and everything
>seemed to be in order.  Sometime during the night, however, the
>filament blew again.   There is no evidence that something funky was
>happening with the power.   So we're at a loss.
>        Has anyone experienced this sort of problem?  Are there any
>diagnostic suggestions?  Any info would be greatly appreciated.
>
>Cheers,
>Kendra Turk
>_________________________
>   Kendra Turk
>   NASA/Ames Research Center
>   Mail Stop 239-4
>   Moffett Field, CA  94035
>    650-604-1430 (voice mail)
>    650-604-6110 (lab)
>   [log in to unmask]




Paul D. Brooks,
Dept. ESPM-ES,
147 Higard Hall MC 3110,
UC Berkeley, Ca. 94720-3110.

phone (510)643-1748,
FAX (510)643-5098.