Author Topic: setting probe current - JEOL8230  (Read 5191 times)

Dan Ruscitto

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setting probe current - JEOL8230
« on: October 17, 2013, 04:58:07 am »
Hi all,
   I've run into an occasional problem. It appears that the timing of PfE reading the beam current on our JEOL 8530F is a little too slow. Occasionally, a data point is assigned the absorbed current value by mistake (which then screws up the quant). Any ideas on how to fix this? Has anyone else run into this problem? Out of 20 points, it occurred 2 times last night.
-Dan
« Last Edit: October 17, 2013, 11:35:34 pm by John Donovan »

John Donovan

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Re: Occasional incorrect beam current reading
« Reply #1 on: October 17, 2013, 09:12:44 am »
Hi Dan,
It's a very strange thing, but every new model JEOL instrument has a slower beam current meter. The old JEOL 8900 reads the beam current reliably with just a few hundred millisec delay after the cup is inserted. The 8200 needs about half a second delay, but the new 8230/8530 instruments seem to need a full 2 seconds of delay after the cup is inserted for a reliable and stable reading of beam current.

Please check your probewin.ini file for these keywords in the [faraday] section:

[faraday]
FaradayWaitInTime=2.0      ; delay after insertion
FaradayWaitOutTime=1.0      ; delay after removal

If your "FaradayWaitInTime" value is already at 2 seconds, try increasing it further.
« Last Edit: October 17, 2013, 11:34:55 pm by John Donovan »
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Dan Ruscitto

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Re: Occasional incorrect beam current reading
« Reply #2 on: October 18, 2013, 01:09:51 pm »
John-
I've increased the delay to 2.2 seconds under 'FaradayWaitInTime=', I have not seen the problem crop up again.
-Dan

ericwgh

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Re: Occasional incorrect beam current reading
« Reply #3 on: November 01, 2013, 02:54:45 pm »
Dan,
I have seen this only once or twice on our 8500 using PFE, so our FaradayWaitTime is probably set just fine. But there was a phase when it occurred occasionally during element mapping with the JEOL software. In a sequence of about 10 maps, it would state an incorrect current for 2-5 maps, and then report the correct current for the others. The maps were good, and based on the raw counts, the actually used current hadn't changed.... haven't seen that issue in the past year.

Eric

Edit by John: Because this is a JEOL specific issue, there is more information here on the JEOL board:

http://probesoftware.com/smf/index.php?topic=26.0
« Last Edit: February 17, 2014, 10:24:40 pm by John Donovan »

Owen Neill

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Re: Occasional incorrect beam current reading
« Reply #4 on: March 28, 2014, 01:19:48 pm »
I had an issue re: reading the beam current last night that seemed germane to this thread. I noticed this due to abnormally high Beam-Drift corrected count-rates (cps/1 na) on certain samples. While all the samples were digitized to run at 50nA, some came back as having been run at 15-17. Turning off the Beam Drift correction shows that the count rates (cps) when it reads 50 nA are the same as when it asks for 50 and reads 17. So we're getting incorrect current readings. Taking out those random points, the beam was remarkably stable (<0.5% variation over 12 hours), and the JEOL engineer was just here touching up column alignments, so it's not real current variation.

My initial thought was that I should just increase the Faraday delay, as per your/Dan's/Eric's suggestions in this thread. However, it had never happened before during my time here, or in the year previous, whereas last night it happened 12 times out of 60. Seems odd that it would happen so often after not happening for so long. I was wondering if any other users had seen anything similar.

John Donovan

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Re: Occasional incorrect beam current reading
« Reply #5 on: March 28, 2014, 01:32:11 pm »
Taking out those random points, the beam was remarkably stable (<0.5% variation over 12 hours), and the JEOL engineer was just here touching up column alignments, so it's not real current variation.

Critical point for *all* JEOL operators: whenever the column alignment is modified in any way, you should always re-run the beam current calibration using the Calibrate Set Beam Current button in the Analytical Conditions dialog as seen here:



Because the beam current calibration on JEOL instruments is set by adjusting the coarse and fine condenser lenses from software.
« Last Edit: March 28, 2014, 01:34:41 pm by John Donovan »
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Owen Neill

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Re: Occasional incorrect beam current reading
« Reply #6 on: March 28, 2014, 01:53:01 pm »
Ran the calibration right after they left, but I'll re-run it again just in case. Again, setting the current isn't the problem (PFE actually gets closer to the requested value than the Unix software), it's the mis-read post-acquisition that seems to be the issue. Seems like increasing the Faraday delay may be the way to go, it just seemed odd that it happened so frequently last night after not happening at all for (as far as anyone here knows) ever.
« Last Edit: March 28, 2014, 01:56:43 pm by Owen Neill »

John Donovan

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Re: Occasional incorrect beam current reading
« Reply #7 on: March 28, 2014, 01:59:44 pm »
Ran the calibration right after they left, but I'll re-run it again just in case. Again, setting the current isn't the problem (PFE actually gets closer to the requested value than the Unix software), it's the mis-read post-acquisition that seems to be the issue. Seems like increasing the Faraday delay may be the way to go, it just seemed odd that it happened so frequently last night after not happening at all for (as far as anyone here knows) ever.

OK, that is interesting. Probably the column alignment changed something, so yes, please try increasing the FaradayWaitInTime in the Probewin.ini file as described above and let us know how long an interval you needed to get reliable beam current readings.

Maybe use the Faraday app for this testing (remember to restart the app after each edit of the Probewin.ini file).
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Owen Neill

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Re: Occasional incorrect beam current reading
« Reply #8 on: April 06, 2014, 05:37:18 pm »

OK, that is interesting. Probably the column alignment changed something, so yes, please try increasing the FaradayWaitInTime in the Probewin.ini file as described above and let us know how long an interval you needed to get reliable beam current readings.

Maybe use the Faraday app for this testing (remember to restart the app after each edit of the Probewin.ini file).

Increased both FaradayWaitInTime and FaradayWaitOutTime to 2 seconds from 1 second, so far so good. Will keep an eye on it.

Edit by John: if it looks good at 2 sec, try decreasing it to 1.5 or so.  Hey 0.5 sec off each analysis- might be worth it as long as the beam current read is reliable!

Forgot to mention, tried 1.5 along the way, same problem (seemed to actually get worse, which was weird). Haven't seen it at 2 yet.

What's really giving me the ulcer is, when we had the column apart, what exactly did we do to the Faraday cup/associated connections to make it read more slowly? Not gonna take it apart again to find out, but still...
« Last Edit: April 08, 2014, 02:28:23 pm by Owen Neill »

John Donovan

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Re: Occasional incorrect beam current reading
« Reply #9 on: April 15, 2014, 05:01:52 pm »
What's really giving me the ulcer is, when we had the column apart, what exactly did we do to the Faraday cup/associated connections to make it read more slowly? Not gonna take it apart again to find out, but still...

I wouldn't worry, JEOL keeps making the picoammeter slower with every new model instrument as described here:

http://probesoftware.com/smf/index.php?topic=80.msg290#msg290
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Probe321

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Re: Occasional incorrect beam current reading
« Reply #10 on: February 28, 2018, 02:02:18 pm »
Thanks John for pointing me to the solution.

Had to set the FaradayWaitInTime= to 2.3 seconds on an 8530F=plus.
« Last Edit: February 28, 2018, 02:25:12 pm by John Donovan »

John Donovan

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Re: Occasional incorrect beam current reading
« Reply #11 on: February 28, 2018, 02:24:38 pm »
Thanks John for pointing me to the solution.

Had to set the FaradayWaitInTime= to 2.3 seconds on an 8530F=plus.

Some 8230/8530 users have had to set the Faraday delay to 2.5 seconds or more.  It seems to depend on the specific instrument.
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UoL EPMA LAB

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setting probe current - JEOL8230
« Reply #12 on: July 26, 2018, 08:05:21 am »
Hi

I'm trying to use a high beam current (500nA). I can not get PFE to set the beam current any higher than about 300 on aperture 3, when I try I get the attached message. The cal set beam runs fine on this aperture.
If I move to a larger aperture, the cal set beam will not run at all - The beam current drops from its initial nA setting through the floor to a few pA and the resultant "curve" is a flat line in the pA range.

I know the stock response to this is that my column is dirty or misaligned, but its not, i've just had a service. I have  increased my faraday wait in time from 3.5s to 5.0s but it's had no effect.
What else can I try?

Richard
Aperture 3
Leeds
« Last Edit: July 26, 2018, 08:16:56 am by UoL EPMA LAB »

Anette von der Handt

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Re: setting probe current - JEOL8230
« Reply #13 on: July 26, 2018, 08:22:31 am »
Hi,

did you try the "calibrate beam current" in the Analytical conditions window? This is especially important after a PM.

Can you set the current in the JEOL software? If so, my next try would be to add (or correct) by hand the respective CL settings in the probewin.ini where the beam current calibration is and see if that helps.
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John Donovan

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Re: setting probe current - JEOL8230
« Reply #14 on: July 26, 2018, 08:56:36 am »
Hi Richard,
As Anette said, after the column has been aligned one needs to re-calibrate the JEOL condenser settings for each aperture as described here:

http://probesoftware.com/smf/index.php?topic=80.msg1007#msg1007

and also here:

http://probesoftware.com/smf/index.php?topic=113.0

This is true for all JEOL instruments. 

By the way, the new JEOL 8230/8530 software now has a firmware call to set the beam current. To utilize this new beam current method simply change the BeamCurrentType parameter in your Probewin.ini file in the [hardware] section, from 0 to 1 like this:

BeamCurrentType=1      ; for JEOL instruments only: 0 = use software iteration, 1 = use firmware iteration (JEOL 8230/8530 only)

Then you won't need to calibrate the JEOL condenser settings in PFE any more because the responsibility falls to the JEOL calibrations.
john
« Last Edit: July 26, 2018, 09:13:32 am by John Donovan »
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