Hi Michael,

When you had the source out did you happen to see if the plug by the gas inlet on the source flange didn't fall in too far? I've had that pin get loose and fall in usually from an accidental bump which then blocks the gas inlet to the source. It's a long shot but something usually overlooked when we're getting tunnel vision on the source itself.

Good Luck!

David Cady
University of Connecticut

On Wednesday, February 15, 2017 5:44 PM, "Tuite, Michael L (3225)" <[log in to unmask]> wrote:

I recently cleaned the source in our Delta V Plus. I also replaced the slit which was quite eroded. On reinstalling the clean source, the sensitivity for both C and N is about a quarter of what it used to be. I’ve tried three different filaments, including the one that was running happily before the cleaning, all with the same results. I’ve tried manual tuning but I don’t get results any better than the auto-tune does. I’ve disassembled and reassembled again checking each ceramic piece and lead. The extraction plates are oriented correctly. The stability of the diminished signal is very good (standard deviation ~ 0.02).  We’ve cleaned the source previously with no problems.

Does this problem sound familiar to anyone? What might I be overlooking? All suggestions are welcome.


Michael Tuite, PhD
Astrobiogeochemistry Lab
Jet Propulsion Laboratory
California Institute of Technology
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818 354-1247 office
626 353-1958 cell