Superconducting Magnet Test

16 10 2010

All photos and videos.

Yesterday I tried the the superconducting magnet‘s persistent switch again.

I failed to make a persistent superconductor, but all the circuits and LabView worked properly. More WIN than FAIL.

 

Superconducting magnet submerged in liquid nitrogen.

 

Conceptually this is the circuit we are testing. The heater functions as a variable resistor. The IGBT functions as the switch. Both are computer controlled.

This is the procedure:

I built a LabView VI to trigger the SC coil a variable number of millisecond after the heater:

We can measure the magnetic field produced with the DC magnetometer:

When I ran the experiment with 5A through the SC coil,  I only saw a tiny magnetic field:

6 Gausse from the SC magnet

Furthermore, use of the heater seemed to make no difference at all.

As a control I ran the magnet in this configuration to see what magnetic field strength we should expect:

The produced a much stronger field:

15 Gauss When connected directly.

So the full current is not going through the main coil, but through the heater. I suspect either the heater resistor is not working (I can hear and see it boil the liquid nitrogen) OR the splice in the coil has more resistance than the coil heater:

The last time I ran this experiment the YBCO corroded from condensation:

This time I ran 2A of current through the coil for several hours to warm and evaporate any moisture.





Superconducting Magnet

15 10 2010

All photos.

I’m almost ready to test the superconducting magnet again. The coil heater and the SC coil are wired up to Labview. The DC magnetometer is showing on a graph in Labview:

I’m still struggling with timed sequences in Labview. I want the SC coil to shutdown x milliseconds after the heater is turned off. I can’t use the wait vi because it stops the whole program.





LabView

8 04 2010

A friend in academia is loaning me his copy of Labview 2009 for Mac / Win. Great news. I got it installed on the mac. I could not install it on the PC, as the PC lacks a DVD drive (CD only). I’m scrounging up an external drive.

We got the last of the parts for the coil power supply today too:

From left to right: Wire would resistors, isolation transformers, and mechanical relays.

Also got some grounding upgrades from mcmaster:








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