[labnetwork] troubleshooting an e-beam source

[Stephen Howe]

In my opinion, you need to study the problem more methodically using
the data you have to find the cause of the problem.For starters I would
plot graphs of how all the parameters you are measuring change during
the incident, which should allow you to see what is causing the
problem.I would guess it looks like a high voltage breakdown.That can
be often due to bad insulation or a vacuum problem . A part of a high
voltage circuit that often fails is the driver part for the signals
which end up sitting at high voltage.As the control signals go from the
part of the circuits at low voltage to the part of the circuits at high
voltage, they have to pass through some kind of  transformer, which can
suffer from problems of large back emfs , which can blow the drivers.
Yours sincerely,
SDI Fabsurplus GroupStephen HoweCompany Owneremail: 
info at fabsurplus.comMobile (USA) : +1 830-388-1071Mobile (Italy) : +39
335-710-7756WWW.FABSURPLUS.COMYour Marketplace for Used Semiconductor
Equipment

On Thu, 2021-07-08 at 10:07 -0700, Nathanael Sieb wrote:
>     Hi all,
> 
>     We are trying to trouble-shoot a PVD e-beam source and can't seem
>       to figure out the problem.  Early in the year we sent the
> assembly
>       out for repair and refurbishment. (we burned a hole in the
>       internal bellows tubing, long story)  When we got it back we
>       connected it back to the system and started it up.  However, we
>       haven't been able to get a stable emission current.  The HV
> stays
>       on but the filament current, and hence emission current,
>       occasionally cuts out.  It comes back a second later, over-
> shoots
>       the target current, and then restabilizes.  It happens at low
>       emission currents and some higher ones.  The timing is random. 
>       Sometimes it happens frequently, sometimes you can run 15 min
>       without a problem.  There are no errors from the power supply.
> 
>     
> 
>     We took a video of the issue and it happens at around the 1min
>       mark here. 
>       The advice from vendors was to look for a loose connection.  We
>       have checked all the external connections and tried to look at
> the
>       internal ones too.  Last week we removed the filament and
>       reinstalled it.  We didn't see any problems and we still have
> the
>       same issue.
> 
>     We're running out of ideas other than sending it back to the
>       vendor to examine the entire assembly again.  Has anyone else
>       encountered this type of problem?  Any suggestions?
> 
>     Thanks,
> 
>       Nathanael
> 
>     
> 
>     
>       
>       
>       
>           Nathanael Sieb  
> 
>           Director of
>               Operations and Administration  |  4D LABS 
>             
> 
>             Simon Fraser University 
> 
>             8888 University Dr., Burnaby, B.C. V5A 1S6
>             
> 
>             T: 778.782.8084 | F: 778.782.3765 | www.4dlabs.ca
>             
> 
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