setting probe current - JEOL8230

[Dan R]

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

[John Donovan]

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.

[Dan R]

John-
I've increased the delay to 2.2 seconds under 'FaradayWaitInTime=', I have not seen the problem crop up again.
-Dan

[ericwgh]

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

[John Donovan]

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.

[John Donovan]

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).

[John Donovan]

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

[Probe321]

Thanks John for pointing me to the solution.

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

[John Donovan]

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.

[UoL EPMA LAB]

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

[Anette von der Handt]

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.

[John Donovan]

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

[UoL EPMA LAB]

Hi Anette/John, thanks for your responses.
Yes I have tried the "calibrate set beam current"   numerous times - that's what my initial enquiry was about. It will only run at aperture 3, on larger apertures the calibration procedure fails.
Yes, the JEOL interface sets the current fine. I will try your suggestion Anette.
I'm intrigued by the software/firmware thing John - what are you calling "new"  for 8230 software?

Gezondheit

Richard

[John Donovan]

Hi Richard,
You might want to contact Gareth Seward as he's in the UK doing the final training for Jon Fellowes at Manchester (on both their JEOL 8530 and Cameca SX100 instruments).

But the easiest thing to do is just edit your Probewin.ini file to utilize the new JEOL firmware call for setting the beam current by editing the beam current type keyword:

BeamCurrentType=1

You will also need to set the EIKS version keyword in the Probewin.ini file if it is not already set to 5:

JEOLEIKSVersionNumber = 5

Both are in the [hardware] section of the probewin.ini file.

That should do it.

That said one can fuss around with the condenser calibration parameters in the probewin.ini file. Here is an example:

Code: [Select]

JeolCondenserCoarseCalibrationSettingLow=65,71,78,80 ; CC high current ~several hundred nA
JeolCondenserCoarseCalibrationSettingMedium=40,57,65,75 ; CC medium current ~25nA
JeolCondenserCoarseCalibrationSettingHigh=36,43,36,36 ; CC low current ~ 1nA

JeolCondenserCoarseCalibrationBeamLow=609.9,107.71,111.71,37.85 ; low probe current setting, last modified 7/31/2013 11:14:49 AM
JeolCondenserCoarseCalibrationBeamMedium=13.836,10.2,10.354,14.09 ; medium probe current setting, last modified 7/31/2013 11:14:49 AM
JeolCondenserCoarseCalibrationBeamHigh=7.491,1.1001,.10031,.023 ; high probe current setting corresponding to high CL, last modified 7/31/2013 11:14:49 AM

JeolCondenserFineCalibrationSetting=255 ; middle of fine cl range is 255 for 8530
JeolCondenserCoarseCalibrationMode= 1 ; 0 = use internal calibration, 1 = use INI file calibration

JeolCondenserNumberOfApertures=4 ; number of sets of probe current calibration data expected

Basically you need to have the number of apertures that you want to utilize for setting the beam current. Then you need to select the aperture in the PFE software since there is no way for the software to know what aperture the instrument is actually using.  Then you click the Calibrate Set Beam Current button for each aperture.   But using the new JEOL firmware call is much easier.

Gareth should be able to help you in any event.