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Hello All,

Thank you much for all your suggestions.

Just to update: I pulled the source again, and decided to put the "new"
Thermo filament back in. I also loosened the one rod where I could pull the
ionization box pin out a bit more (and re tighten) so that there is a
better connection. I think that resulted in the now Box = 0.68 and Trap =
0.82 mA with decent signal. Hope it remains so after a good baking.

cheers,
-Herb

On Sat, Dec 20, 2014 at 5:23 PM, gerard olack <[log in to unmask]>
wrote:

>  hI Herb--
>
> Interesting.....
>
> Hagit's suggestion is really good.  If there's a hot spot on the filament,
> the electrons could be shot off to the side, so to speak, directly into the
> "box" and never make it to the trap.
>
> I'm not exactly sure what happens if the trap and box short.  I'm guessing
> you won't pick it up when you check, but the trap can twist, and if there's
> only a tiny gap between them--you might get shorting at high voltage and
> with some gas pressure in the source.
>
> The same can be said for the hood on the filament, and Chris is probably
> on to something in this case.  Also, if the magnet is not completely
> secure, it might sag and the holder get a little too close to the filament
> housing for comfort.  Over tightening might lead to the same problem--not
> sagging, but magnet holder getting too close to the filament housing.  Make
> sure the spacers are not flaring.
>
> I've also had issues with the filament holder not sitting flat against the
> box.  If you're using washers there, make sure they're only on the alumna,
> and not catching on the lip of cutout in the box.  That can prevent the
> filament holder from sitting flat against the box.
>
> good luck!
>
> take care,
>
> gerry
>
>
>
> On 12/20/2014 3:14 PM, Herbert Tobias wrote:
>
> Hi All,
>
>  Still having high box current problem on MAT 253.
>
>  As per Gerard's suggestion, I checked the trap lead connection. When
> removed source, it was good and connected.
> As per Hagit, I already tried reattaching filament.
> Today I replaced the filament with a new one (actually SIS repaired) and
> now Box = 1.24, Trap = 0.26 mA. Just arced and now Box =1.38, Trap = 0.12
> mA.
>
>  Yesterday with previous filament (a new Thermo one), when I heat up
> source to ~60C, the Box = 0.65, Trap = 0.85 with OK signal (40% less than
> ideal).
> But then went back to Box = 1.5 mA, Trap = 0 mA after source got hotter
> (80C). And stayed as such when cooled. Was arcing often.
>
>  Any other suggestions?
>
>  thanks,
> -Herb
>
>
> On Fri, Dec 19, 2014 at 11:34 AM, hagit affek <[log in to unmask]>
> wrote:
>
>> Hi Herb
>> This happened to us once before. the trapped hovered close to zero
>> instead of our usual ~0.5 and box was close to 1.5. signal intensity was
>> normal but the delta values were very noisy and probably the beam was not
>> stable. the solution was to open the source again, detach the filament and
>> then reattach it.
>> hagit
>>
>> ----
>> Hagit P. Affek
>> Associate professor
>> Dept. of Geology & Geophysics
>> Yale University
>> 210 Whitney Ave.
>> PO Box 208109
>> New Haven, CT 06520-8109
>> phone: 203-432-3761
>>
>>
>> On 12/19/14, 11:11 AM, Herbert Tobias wrote:
>>
>>> Hi All,
>>>
>>> This week I cleaned the source of our MAT 253 and installed a new Thermo
>>> filament. Apart from resolving a bunch of annoying issues over the days,
>>> and re-cleaning yesterday, the Trap current on the system is currently
>>> reading Zero (0), while the Box current reads the emission I set in the
>>> focus settings (i.e. 1.5 mA or 1.0 mA etc). All through the week and just
>>> this morning the Box and Trap current was reading approximately equal (i.e.
>>> 0.75 mA and 0.75 mA). Right now for the past couple hours it is lopsided as
>>> noted above (Box= 1.5 mA and Trap = 0 mA). But the instrument does provide
>>> strong signal for CO2 (m/z 44 = ~4500 mV at 1.5 bar on Ref 1 of a Conflo
>>> III). I measure no shorts to the Trap. I decided to start baking the system
>>> for awhile and see what happens. Any thoughts?
>>>
>>> (Title of e-mail sounds like a psychological thriller, eh?)
>>>
>>> thanks and regards
>>> -Herb
>>>
>>> --
>>> Dr. Herbert Tobias
>>> Sr. Research Associate
>>> Division of Nutritional Sciences
>>> 244 Garden Ave
>>> Cornell University
>>> Ithaca NY 14853
>>> 1-607-255-9009
>>>
>>
>
>
>  --
>  Dr. Herbert Tobias
> Sr. Research Associate
> Division of Nutritional Sciences
> 244 Garden Ave
> Cornell University
> Ithaca NY 14853
> 1-607-255-9009
>
>
>


-- 
Dr. Herbert Tobias
Sr. Research Associate
Division of Nutritional Sciences
244 Garden Ave
Cornell University
Ithaca NY 14853
1-607-255-9009