Hello Jessica,
I no longer have an evaporator, we now use "exchange" systems to get to
very low sample temperatures. So I am only going by memory.
If I remember correctly, you have access to a "heater power" setting for
your evaporator. Perhaps contradictory, if you increase the "heater"
power for your evaporator, you in fact increase the flow of cold
nitrogen gas, which should lead to lower temperatures. Maybe you need
to increase your evaporator heater power.
If you find that you are unable to increase your evaporator heater power
in software, maybe there is a "max power" setting somewhere in the EDTE
configuration.
When we last used the evaporator (5+ years ago on an AV-1 system) we
were able to get to 190K without too much trouble.
Good luck,
Bob.
On 2024-07-11 3:47 p.m., Roberts, Jessica via groups.io wrote:
>
>
> Hi everyone,
>
> I hope this email finds you all happy and healthy! I have been
> troubleshooting cold VT NMR on my 500 MHz (Ascend 500 with Avance III
> HD console) instrument and was hoping to find some insight here. I
> have attempted to run cold VT NMR with two different LN2 evaporators
> and have had similar circumstances occur; I am wondering if there is a
> configuration/firmware based issue here.
>
> Essentially, I am trying to cool down to at least -50 C, though cooler
> would be better. I have appropriately set up the instrumentation,
> connected the LN2 evaporator, etc, but can only cool down to 235.7 K.
> I have been cautious about the condensation formation and have been
> keeping the probe-facing portion of the setup dry throughout this
> whole process to avoid any ice-related issues. After receiving the
> insufficient chilling status on the temperature control suite, I
> navigated to the LN2 evaporator and dewar. After disconnecting from
> the probe, there is still cold N2 gas being pushed through the line. I
> can also confirm I had sufficient LN2 in the dewar at the time of the
> error. I had an issue with insufficient chilling in the past, though I
> cannot currently recall what temperature I was able to get down to
> previously. I am wondering if there is anything software or
> configuration side that might be the cause? I would suspect if the LN2
> evaporator electronics were the issue, I would not be able to cool
> down that far - but perhaps I am missing something!
>
> If anyone has any insight or suggestions, I would be grateful!
>
> Thanks all and happy resonating!
> 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
>
--
Dr. Bob Berno
Manager, NMR Facility
McMaster University, ABB-156
1280 Main St. West
Hamilton, ON L8S 4M1
T: 905-525-9140 x24158 or x24686
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Received on Thu Jul 11 2024 - 13:57:25 MST