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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