Copasetic Flow

I didn't make it into the lab today what with the holiday and all, but I did have time to read one of my favorite journals, American Mathematical Monthly from the  +Mathematical Association of America  .  The journal features a very interesting article[1] by Marshall Hampton[3] about cosine identities.  The article got me back to musing about solving for potentials with spherical symmetries and Legendre polynomials again[5].  I don't have time to work through this now, so I'm just recording my meandering thoughts here for future self, and anyone else that would like to take a look. Hampton writes down the generalization of the law of cosines for polyhedra rather than just the plane, (pun intended), old triangle.  Here it is $$0 = \sum_j\vec{n}_i\cdot\vec{n}_j\Delta_j = \Delta\left(i\right) - \sum_j c_{ij}\Delta_j$$ Where, $$c_{ij}$$ is the cosine between two faces of the polyhedra i and j, and $$\vec{n}_i$$ is a vector field normal to th...

Took apart the apparatus at the bottom of the proposed Dewar stick.  This is stick that will eventually support all the required apparatus in liquid helium.  Pictures follow.  Per normal, if this is your first day on the site, scroll to the bottom for the experimental background. The inside of the Dewar measure out at 1 and 1/8 inches.  That works out to about 1.25 cm.  Then, plugging that into an expression for the size of cylinder we can get to fit Working with square cylinders Inscribe a square inside a circle circle radius 0.5625 1.42875 cm square side 0.795495129 1.010279 cm Square radius 1.010278814 The above distances are to the wall of the Dewar.  If we back off of this a little bit and give ourselves  an 1/8 of an inch clearance at all the corners, we get ...

In all likelihood, we’ll go with a resistive measurement, (to detect the superconducting state or lack thereof), using a small lead wire.  The following setup is from an Alfred Leitner video.   We’ll use something even simpler, probably just a lead wire with a four point probe attached.  By the way, if you're new to the game, scroll to the bottom for background information. We could sputter a line of lead onto a glass slide, but I don’t see the benefit yet. Working on finding out what it is. Check this out later in the day per shaping samples: https://plus.google.com/116395125136223897621/posts/9c7dFfZ7ijT I’m performing the check on the resistance of the primary coil as its cooled by liquid nitrogen.  The idea is that yesterday’s increase in output ignal with the superconductor ooled may have noly been do to the primary pulling more current as its resistance ramped down.  Here are a few pictures of the assembly being taken apart for the present...

If you're new to the experiment, scroll to the bottom for background that will catch you up with what's going on. Liquid Nitrogen Fill The liquid nitrogen Dewar has been filled.  It’s initial and final weights were 146 and 170 pounds, respectively.  I’m guessing I must have read the initial weight incorrectly, but we may be paying too much for ’45 liters’ of nitrogen which might be closer to 13. liters/pound 0.5606 start 146 finish 170 net 24 Total Liters 13.4544 I’m doing the same measurement as yesterday with the sample immersed in liquid nitrogen.  There seems to be no change.  I have however invented a reasonably good vibration detector for the vacuum pump across the room, see video here . I’m going to try a new configuration of the two coils next.  Pancake coils will be constructed with one placed on each of the opposi...

If you're new to the experiment and need background, scroll down. I’m trying out the concept for the qualitative quench detector with a YBCO sample.   The prototype coils were wrapped directly on the YBCO sample.   The coils are constructed with manget wire.  The insulation on the ends of each coil was scraped off using a razor blade.  The brown material is just dense poster-board stock that provides a mounting frame for the coils. Without cooling the sample, (so that it remained in its normal state), an oscillating current was driven through the primary coil and read through the secondary.  The results were the same as might be expected with air core coils since the superconducting sample is not diamagnetic or ferromagnetic.  Tomorrow the same experiment will be run again with the sample in its superconducting state.  I expect to see a different x-y plot due to the superconducting samples expulsion of magnetic fields in i...