Hi Million,

First thing to check would be for continuity across the filament, just
in case you've got a DOA filament (it happens).

As you have mentioned yourself already, this could just be a slight
misalignment of the source leading to an eclipsed alignment of the gas
inlet like so (), or worse. Runnung a magnet background scan first is
definitely a good idea. Unless there is something seriously wrong with
the source (no emission) or the analyzer, you should see peaks for N2
background at around 8,500 steps, give or take.

If you see the N2 peaks suggesting there is nothing wrong with either
source or analyzer per se, switch the source off, open the door and
disconnect all the supply cables. 

If you are careful you can get away with not turning the pumps off but
this is up to you. Loosen the bolts ever so slightly until you can
wiggle the source flange left to right and back. Twist it to the left
(gently does it) and mark the stop position with a felt pen (across
housing and flange at the 9 o'clock position where the alignment marker
is). Now twist it to righ until it will go no further and mark this
position too. Twist to the left again until you are halfway between the
either extreme. This should now have the gas inlet holes aligned like
so: O.



Dr W Meier-Augenstein, CChem, FRSC 

Extension: 2624 
E-mail: [log in to unmask] 
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-----Original Message-----
From: Stable Isotope Geochemistry [mailto:[log in to unmask]] On
Behalf Of Million Hailemichael
Sent: 11 July 2010 21:07
To: [log in to unmask]
Subject: [ISOGEOCHEM] no ion beams after source cleaning

I removed and cleaned the ion source for our delta V advantage. I
changed a new filament and I put back the source and everything looks
fine on isodat screen. Values are...

HV= 3.01KV
Box= 0.72 mA
Trap= 0.77 mA
vacuum= 1.4e-006
Magnet (steps)= 11572 

When I select reference gas (CO2) on the conflo screen to do a jump
calibration no CO2 gas is flowing into the system. I checked for a leak
and NO leak, we have a half tank CO2 gas. It seems ions are not reaching
the cups or ions are not generated. I checked the CO2 tank is open,
conflo is open and SGE valve is open.

I am planning to remove the source again and see if the small opening in
the side of the ion source chamber is somehow blocked or miss aligned
(even though I checked every thing before I put it back) . Or when I
pushed the source into the mass spectrometer possibly a wire may have
been disconnected?. 

Any advice or suggestions before I remove the ion source again to check
for any loose connection.


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