[3dem] Issues with FEG

[Ric Aramayo]

 Dear colleagues,

We are installing a CM200 FEG in our facility. However, we are having
issues with flash overs that are happening shortly (~24h) after reaching
the high tension of 200 kV. We have tried a few things to improve the
stability of the system: change the HT cable from the HT tank to the
microscope, cleaning the IGP2 pump or ramping up the HT slowly to 200 kV
with small voltage steps (< 0.2 kV).

Unfortunately, we are still experiencing those problems. The microscope has
been operating now for a couple of months at 160 kV now. Does anyone have a
suggestion of what we could try next?
Many thanks for any suggestion,
Ricardo.

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Ricardo Aramayo
Imperial College London
Du Caine Road, W12 0NN London
United Kingdom
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