AMMRL: Re: For Varian Cold-Probe Users who have upgraded to an Ion-Pump...

Janusz Koscielniak (koscieln@ncifcrf.gov)
Thu, 24 Jan 2008 15:01:14 -0500 

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Rich touches the problem about which I have complained mightily to multiple
Varian people, after I learned that for all this money they sell just a
standalone ion pump not connected to cryobay computer. 

There are two realistic scenarios I was able to come up with:

1.       The compressor stops and probe warms up. Then outgasssing will
overload the ion pump, but will not damage it permanently - I was able to
pump it out on couple of occasions and it worked fine afterwards,

2.       There is a brake in a vacuum line then the ion pump will likely be
damaged, but  bigger concern is about cryoprobe itself - the compressor
should be stopped immediately on vacuum loss.

I believe that some (or perhaps all) Mark2 systems were shipped with IMG
gauge in which vacuum reading is done by cryobay software and when 'vacuum
monitor' is enabled it would stop the probe on vacuum loss. From this point
on there was 'vacuum channel' in Cryobay console, which was later modified
to accommodate ion pump.

When ordering the ion pump I was sure that Varian will at least provide
software upgrade and perhaps some pointers on how to wire it to NI ADC card
which is reading all other channels. 

I am wondering how many labs share the same concerns about removing this
protection layer which already existed at least with Mark2 systems with IMG
gauge.

The solution Rich is describing is good, but upgrading cryobay software and
wiring ion pump to it would be even better.

 

Janusz Koscielniak

 

Research Engineer

NCI Frederick

Tel: 301-846-5213

e-mail: koscieln@ncifcrf.gov

 


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Rich touches the problem about which I have =
complained mightily
to multiple Varian people, after I learned that for all this money they =
sell
just a standalone ion pump not connected to cryobay computer. =




There are two realistic scenarios I was able to =
come up with:



1.      
The compressor stops and probe warms up. Then
outgasssing will overload the ion pump, but will not damage it =
permanently –
I was able to pump it out on couple of occasions and it worked fine =
afterwards,



2.      
There is a brake in a vacuum line then the ion =
pump
will likely be damaged, but  bigger concern is about cryoprobe =
itself –
the compressor should be stopped immediately on vacuum =
loss.



I believe that some (or perhaps all) Mark2 systems =
were shipped
with IMG gauge in which vacuum reading is done by cryobay software and =
when ‘vacuum
monitor’ is enabled it would stop the probe on vacuum loss. From =
this
point on there was ‘vacuum channel’ in Cryobay console, =
which was
later modified to accommodate ion pump.



When ordering the ion pump I was sure that Varian =
will at
least provide software upgrade and perhaps some pointers on how to wire =
it to NI
ADC card which is reading all other channels. 



I am wondering how many labs share the same =
concerns about
removing this protection layer which already existed at least with Mark2
systems with IMG gauge.



The solution Rich is describing is good, but =
upgrading
cryobay software and wiring ion pump to it would be even =
better.



 



Janusz Koscielniak



 



Research Engineer



NCI Frederick



Tel: 301-846-5213



e-mail: koscieln@ncifcrf.gov



 









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