Progress Update

12 08 2009

Todd T. From Swagelok stopped by the shop and we quickly built a parts list for the deuterium system and the RGA. Turns out we are using a VCR style Swageloks, and they require a single use steel gasket much like the copper gasket in a conflat.

Also made a first pass at building the persistent switch. Here you see 50cm of insulated nicrome wire wrapped around 5cm of YBCO:

IMG_3915

Cover in Kapton tape:

IMG_3916

Connect a multi meter across the YBCO, and wire up the nicrome wire to a variable power supply:IMG_3920

And into the cold:

IMG_3921

Unfortunately I was not able to get any reliable readings from the ohm meter. Before I turned the heater on, the meter registered between -0.5 ohms to  0.4 ohms. Any change in resistance from turning on the heater was lost in the meters margin of error. However the heater does turn on and work. You can hear the LN2 boiling off when you set the heater current to about 1.5 amps. So not exactly sure how to meter and test the persistent switch… for all we know this one works. And really this makes perfect sense: the resistance of the multimeter probes should be greater than the strip of superconductor even in it’s resistive state.

Coming out of the LN2:

IMG_3922

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5 responses

13 08 2009
theorbtwo

Can you set up your switch as half of a resistor-divider to get a larger signal swing? (I suppose you’ve got a bit of a problem when one leg of a divider is zero, but you can always stick a 1ohm resistor in series with the switch, and try to find the difference between 1 and 1.1.)
(Please, feel free to tell me that’s a crazy idea.)

16 08 2009
17 08 2009
theorbtwo

That wasn’t what I was thinking of, but looks a lot saner!

19 08 2009
Superconducting Magnet Test « Prometheus Fusion Perfection

[…] we turned on the heater up to 1 amp, based on previous experimentation. From there we incrementally raised the amperage, waiting about 1 minute between steps. The good […]

5 12 2009
someone

how are you planing to make a superconducting connection from the switch to the coil ? or is the connection resistance low enough to be ignored ?
sorry for my bad English (not my native language)

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