Wednesday, July 2, 2008



Well, I am coming to terms with the sinusoidal nature scientific progress. Frustration and slow progress is followed by moments of clarity and amazing results. Both Monday and Tuesday were less than stellar in terms of progress toward our ultimate goal.

The one upside of Monday's experiments was that we were able to have a pellet move along a curved track. There appears to be some critical distance beyond which the magnetic field no longer levitates the superconductor. I didn't measure that distance, but it is in the range of 3-4 mm. So, the track is ready, now we need a vehicle.
Let me back up. The current idea for our vehicle design will be a styrofoam body, with a metal bottom. The superconductors will be affixed to the underside of the metal. Inside the styrofoam body, we will pour the liquid nitrogen which will hopefully lower the temperature of the superconductors below their critical temperature. Below are some pictures of our initial design.

This was constructed from two corners of a styrofoam cooler, then glued together with styrofoam glue from Michaels craft store. It really looks, smells and feels like Elmers, but I'm a sucker for marketing and new packaging. However, this design did functions as a liquid nitrogen reservoir. There was some initial leaking, but a second layer of glue has proved to be an effective seal.

In attempting to engineer this design, these past two days were really slow-going and fraught with trials that did not work. The mass of the vehicle is going to be an issue. The sample superconductors that we have been using cannot levitate more than 2-3 grams. Consequently, my design for the vehicle underwent a series of shavings, clippings and trimmings that cut its mass from 5.0 g to 2.4 g. See below for some pictures of the evolution of the design taking mass into consideration.
The mass of this design still proved to be too much for the sample superconductors that we had.
I may not have mentioned this in all my worries about vehicle construction. On Monday, 7/1 our own samples came out of the furnace in which they were annealed in oxygen. This was to add the final oxygen atom to the unit cell of our crystal structure.
Early Monday, we tested the Meissner effect and our pellets were less than stellar. The pellet would levitate, but not evenly. It would hover at an angle, and increased in temperature much faster than the samples we had been previously working with. There may have been some impurities, or the annealing process may have been incomplete. To try and fix this, we set the pellets for another annealing in oxygen for 36 hours. Hopefully, an additional heating will improve the purity and the pellets' ability to levitate.

No comments: