I re-spooled the YBCO on it’s original spool. Hoping for a stronger magnet and less liquid nitrogen.
We ran 2A DC through the coil at room temperature and David searched for the strongest point of the field.
Which turned out to be the very center, perhaps amplified by the ferrous steel screw:
In this configuration we are seeing ~140 gauss magnetic field while running 5A DC current through the SC magnet submerged in liquid nitrogen (with no persistent switch short circuit):
Much better!
Next we re-fabricated the persistent switch… this time using a much longer splice, better soldering, and a longer heater directly over the splice:
We also included some heat shrink tubing to insulate the heater:
We will test this again today!
Why are you soldering the splice? Doesn’t that add resistance? Shouldn’t it be a mechanical connection?
You are correct, the splice will be somewhat resistive.
There is no way to do a true superconductive splice as the YBCO layer is embedded inside the copper:
So either a solder or mechanical connection will at best be a traditional copper joint.
You best remedy is to make the splice longer and therefor less resistive.
Yeah, solder == non superconducting. If you have non SC material in your circuit it will stop the electrons instantly when you remove the current source.