Dear Hiua Daraei

I worked with cryostats for Mossbauer spectroscopy and and VSM. What we normally did before transferring the liquid helium was: get a good vacuum, put the N2 to lower the temperature and improve the vacuum - if necessary, remove the N2 and put it again to remove impurities.

See if the cryostat is condensing water on its surface.

Afterwards improves the vacuum and finally, initate the transfer of helium, little by little, until the temperature was lowered well - this way we were going until we managed to keep the liquid helium.

You have to make sure that the liquid Helio covers the coil before turning it on!!!

I hope I could help, good luck

Carlos

I recommend that the Bruker engineer be in charge of this process. A quenched magnet is the worst breakdown that can occur in the NMR and it has to be Bruker who does it. The problem will also be the cost. The same thing happened at my university during a renovation of the lab and we are currently waiting for them to come and repair it. Luck!

I recommend that the Bruker engineer be in charge of this process. A quenched magnet is the worst breakdown that can occur in the NMR and it has to be Bruker who does it. The problem will also be the cost. The same thing happened at my university during a renovation of the lab and we are currently waiting for them to come and repair it. Luck!

Yes the re-energizing is a long process (several days?). During this time there is a lot of boil off - it takes a liitle time for the magic of super-conductivity to work.

I would imagine that not only do you need many amps but it needs to be regulated fairly acurately. As I remember the procedure is to connect a shunt across the magnet windings and feed in the current across that shunt.

As others have said suck it up and get Bruker in.

Re-energising a magnet is a very technical process. Cooling down is just the first step and it consumes a huge amount of helium (and liq N2 initially). Once it is cold, you can't just push some current in and hope that it will work. The engineers must have a special power supply and the magnet will have a specific power-up process where the current is increased at different rates over time.

A heater current is applied to a superconducting switch to enable charging to take place. Once it is at field and stable, you then have to put current into the superconducting shims according to the factory settings and then change these to get a rough shim. At various points in the process, current will be induced into different coils and these will need to be dumped in order to get a working magnet. Once the charging is complete, the superconducting switch is closed by turning off the heater current.

As others have said, don't even think about trying to do this yourself. You don't have the tools or the knowledge to do this highly technical operation and it will simply cost you a lot of money for all the helium that you will waste.