I think when the valve is opened the instruments checks the Penning gauge
to make sure there is no unusual drop in vacuum. It sounds like it is
getting a bad reading, so maybe this is an electrical problem with the
Penning or maybe it just needs to be cleaned. Alternatively, it is possible
that the plasma is shut off due to an actual spike in plasma reflected
power, which would close the gate valve as well. Unless there is something
obviously wrong with the valve itself, I wouldn't put too much stock in the
On Thu, Aug 9, 2018 at 11:28 AM, Pieter Vermeesch <[log in to unmask]>
> When I start our Agilent 7700x quadrupole ICP-MS, the plasma comes on,
> moves towards the cone and then shuts down producing the following error
> 1230, Error: Plasma was shutoff when opening gate valve
> and occasionally:
> 1135, Error: Malfunction on gate valve open. Valve closed again.
> Things I tried to fix the problem:
> 1. Switch from laser ablation to solution mode. This initially produced
> two new error messages:
> 1233, Error: RF generator has switched 48V power supply off
> 1218, Error: Plasma was shutoff (Plasma RF Monitor)
> 2. Cut back the fibre-optic cable in the source. This removed errors 1233
> and 1218 but brought back errors 1230 and 1135.
> I don't know if this is relevant, but the MassHunter software briefly
> reports an Analyzer Pressure of 8E+6 Pa immediately after the error. Then
> it changes back to the usual 9E-6 Pa. I don't know if this has anything to
> do with the problem. A megapascal of pressure seems rather impossible.
> Pieter Vermeesch
> London Geochronology Centre
> University College London
"If I have seen further, it is by standing on the shoulders of Giants"
"Somewhere I think I have read an alternative quotation "I have stood on
the shoulders of pygmies". It is a clever remark [...] There is, however
the sobering thought that in a land of giants and pygmies there is no point
in standing on the shoulders of a pygmy if one is a pygmy oneself"
"If I have seen further, it is because I was looking in the right direction"
"If I have not seen very far, it is because Giants were blocking my view"
Johan, on an average day
Dr. Johan Schijf
Associate Professor, Aquatic Environmental Geochemistry
UMCES/Chesapeake Biological Laboratory
P.O. Box 38, 146 Williams Street
Solomons, MD 20688-0038
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