> Atlas barrel toroid successfully powered up on first attempt.
>
> How hard can it be to power up a toroid???

Actually powering up a liquid helium cooled magnet of any shape is quite an 
exercise. You don't "just" cool it down and turn the power on.

There is quite a process to go through, colloquially known as "training" the 
magnet. Sure you cool the magnet down, and then run some current through it. 
But you have to turn the current up slowly, and then at some point the 
magnet field inside the winding gets to such a strength that a turn of the 
winding will decide that it would much rather move "over there" from where 
it is sitting. This creates a local heat spot which boils the helium which 
creates more heat due to gas pressure which boils more helium ... well you 
get the idea, you have a sudden blow of helium gas out a safety vent.

Then you start the process over again, refilling with helium liquid, and 
ramping up the current until the next incident. Eventually you get to a 
point where all the miniscule movable bits have moved into their lowest 
energy/most stable magnetic positions, and you can run the magnet at full 
designed current.

It sounds to me as though the "powering up of the toroid" referred to above 
is the process of going through this training. 

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