Hi,
we are operating a number of D+XL's since long and seem to have been
lucky with the HV tripping business. So, I can offer only a suspicion as
to where to look for. I have 3 suggestions:
1. If the ion source has been operated for some time (with high
sensitivity, i.e. high ion currents a week may be plenty) there is a
risk that enough material has been sputtered from the entrance slit area
that the insulation across the big quartz ring has deteriorated enough
to cause some sparking. Cleaning then is necessary (with HCl to get rid
of Ta, with HCl+HNO3 in the case of a Au slit)
2. All HV supplies have a maximum load setting in order to save peoples
lives. In order to accomplish this task, the trip circuits also have to
be fast. However, if they are too fast, they may become vulnerable
against minor sparks as mentioned under (1). In the D+XL one can at
least set the trip level on the PCB (R33, 'overload adjust'), it might
be set too sensitive. Clockwise is less sensitive (I think). The
standard setting is arount '1 pm'. A word of caution: Do NOT operate on
the source supply with the HV on !!
3. The ion source is protected against high pressures using the Penning
gauge. If the Penning starts to deliver erroneous pressures, the trip
might be initiated. However, this should trip the whole ion source, not
just the HV.
I am not so familiar with the new electronics in the D+XP, but the
design principles should be similar.
Willi
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Willi A. Brand, Stable Isotope Laboratory [log in to unmask]
Max-Planck-Institute for Biogeochemistry
Beutenberg Campus
Hans-Knoell-Str. 10, 07745 Jena, Germany Tel: +49-3641-576400
P.O.Box 100164, 07701 Jena, Germany Fax: +49-3641-577400
http://www.bgc-jena.mpg.de/
http://www.bgc-jena.mpg.de/service/iso_gas_lab/
GASIR 2005 in Jena:
http://www.bgc-jena.mpg.de/service/iso_gas_lab/gasir2005/index.shtml
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