Tuesday, July 22, 2008

Track Design


As we near the end of the RET, we have been finalizing certain aspects of the project. We had initially intended to make a track that was an oval, which the vehicle could circumnavigate. However, that was a bit impractical because the magnets are quite expensive, and funding an entire oval would cost about $1200. As it is, Ram was quite generous and we have nearly $500 worth of magnets as our track. Not being able to construct a complete track, we fashioned the magnets into the shape of California.

We kept the track with four-wide magnets, with alternating poles (N-S-N-S). At the place where San Francisco would be, we removed two of the "coastal" magnets. Since the pellets will move stably over three-wide magnets, the vehicles can navigate through the "bay" with ease. Below is a bit of the evolution of the California track. We have painted the base (magnetic stainless steel) to help show it as California. The blocks of magnets on the side are the Channel Islands, complete with polarity arrangements to allow pellets to head out to the islands and "just hang out." I think that could be a nice educational tool, because it will be easier to see how stable the pellets are, and the smaller magnetic base might be easier to explain than the entire track.

Monday, July 21, 2008

Batch Two is great!

Over the course of the past 2-3 weeks, we have been making a second batch of superconductor pellets. It is somewhat following the "more is better" philosophy that we have adopted in developing this levitating vehicle. Having more pellets allows us to make more vehicles, with possibly more pellets in each vehicle, improving their levitating power.

We made a few changes to the synthesis procedure, but one appears to be most significant. For the first preparation we used a long-cylindrical boat crucible made of alumina. The pellets leaned against the sides of the boat. We were pleased with the levitating results that we observed, but the diffraction data was a little messy. We theorized that the aberrant peaks were likely due to alumina contaminating the pellets. To avoid this, we used a more upright alumina crucible, and stacked the pellets so that they would not touch the sides.

This second batch levitates amazingly higher than our previous preparation, and the diffraction data is much cleaner, matching the reference scans with much more precision. Below are two pictures, before and after. The pictures were not taken at exactly the same angle and distance, but I think the difference in levitating ability is clear.

Another picture of the levitation with the new batch of YBCO: