Jessica,
The probe heads are actually quite robust. You have to be very careful when
removing them from the bore, though, since they're fairly heavy and unbalanced.
Typically, it's a 2 man job, where one person supports the probe from the
bottom, while the other stabilizes the rest of it as it's gently lowered.
We have two of the later generation TCI Cryoprobes in our facility (600 MHz, 850 MHz).
The TCI-600 has been in constant use since 2008, while the TCI-850 has been in
constant use since 2013. Both of these probes have fantastic specs in terms of
sensitivity, resolution, etc.
The only glitch I've had was that the 13C cold preamp on the 600 died a few
years ago. Since we use don't use this instrument for direct 13C detection,
that's something we can live with, and if I really need to run direct acquisition
13C, I'll put the probe in bypass mode, where it gives about the same sensitivity
as a room temperature TXI probe.
There was also a gradient failure on the 850 that required sending it back
to Switzerland, but otherwise, the probe has held steady the entire time of
constant use.
There really isn't much you have to do in between the annual servicing of your
Cryoprobes, since the engineer who does the service will take care of the
components that show wear and tear (replacing the cold head, roughing pump
refurbishing, replacing the turbopump if necessary).
Once in a while, though, you'll probably have to re-cool down the probe head,
since interruptions in your compressed air supply will mean that your Cryoprobe
will force itself to warm up. If your probe has been operating constantly for
several months, then you'll have to pump out the coldbox in the Cryoplatform,
and the Cryoprobe itself, since there's probably going to be a lot of accumulated
moisture and other contaminants, before you can start cooling down the probe again.
Also, if you're using an outdoor air-cooled helium compressor, you'll probably
want to clean off the compressor coils every 4 months or so if there's a lot
of dust and dirt around your area (e.g. if a lot of building construction is
going on nearby). This can be done with any standard air conditioner compressor
coil cleaner that you can buy at any of the big box stores, or you can use something
like Nu Brite foaming coil cleaner, where a single jug will last you a very long time.
Best regards,
Ronald Shin
University of Alabama at Birmingham
Central Alabama High Field NMR Facility
> From: main_at_ammrl.groups.io <main_at_ammrl.groups.io> On Behalf Of Roberts, Jessica via groups.io
> Sent: Thursday, August 31, 2023 6:16 AM
> To: main_at_ammrl.groups.io
> Subject: Re: [AMMRL] Question about LHe cryoprobe costs/He recovery
Hi everyone,
Thank you all so much for your responses. I am happy to know it is a closed
loop system; I just wanted to make sure what all the added expenses are you
have to deal with in order to benefit from the probe technology itself. A few
things I should have included in the original email:
1. I would likely keep the LHe cryoprobe installed and not do probe switches
in that instrument. Goal is to acquire a second instrument, and hopefully have a
Prodigy probe installed on one that could then be used for switching to other
probes based on user needs, and one instrument to run LHe cryoprobe exclusively.
2. I am hoping to install the LHe onto a Bruker 400 MHz Avance.
How robust are the probes themselves? In addition to the added coldhead/regular
maintenance expenses, how often have you had the probe go down/require additional
Bruker visits/had to send the probe in for repairs?
Thanks again everyone!
Jessica
Dr. Jessica M. Roberts, Ph.D.
Assistant Professor of Instruction
NMR Facility Manager
Department of Chemistry and Biochemistry
Ohio University
245 Chemistry
Athens, OH 45701
740.593.0038
jroberts_at_ohio.edu<mailto:jroberts_at_ohio.edu>
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Received on Thu Aug 31 2023 - 06:29:49 MST