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A Horse Trough a Quonset Hut and Data Acquisition

It gets hot in Las Cruces, and sometimes there's nothing to do for it but take a dip.  That's how I found myself sitting in our horse trough with Junior this weekend cogitating about the new data acquisition system.  I had a glass of McAllen, and Junior had her boat, (at 17 months, she's much too young for McAllen), and a good time was had by all.  The horse trough is left over from when we lived in a Quonset hut.  The building didn't come with a bathtub, but a short trip to the local feed store a few blocks away and we were set.  It was kind of cush, the trough sat near the back door about five paces from the train tracks, so you could sit there and watch the trains go by, (see the video below). That was before our landlord decided the space would make a better art gallery. I digress though!  Back to the data acquisition system and its requirements.  I've come across two articles about the effect of alternating current magnetic fields on supe...

Superconductor Trapped Field and its AC Attenuation: Weekend Reading

I'll be doing some reading this weekend trying to get some more information behind the experimental results I've seen this week.  The rough observations this week were: 1.  Levitation force seems to go down for the same peak magnetic field as frequency increases. 2.  The levitation force can be increased at a given frequency by increasing the peak magnetic field. I haven't found much research that measures the levitation force between an AC electromagnet and a superconductor.  I have found some interesting papers on the attenuation of magnetic flux trapped within a superconductor when an AC magnetic field is applied to the superconductor.  Two of the more interesting papers I've found are Ueda, H., Itoh, M., & Ishiyama, a. (2003). Trapped field characteristic of HTS bulk in AC external magnetic field. IEEE Transactions on Appiled Superconductivity, 13(2), 2283-2286. doi:10.1109/TASC.2003.813075 and Ogawa, J., Iwamoto, M., Yamagishi, K., Tsukamot...

Levitation Frequency Characterization: Train of Lab Work Notes

Great news!  The bridged output mode on the Peavey amplifier I'm using here works!  That means I can apply roughly twice as much power to the levitation force providing electromagnet.  The bridge mode appeared not to be working two days ago.  A little reading of the manual provided the reason.  When in bridge mode, the speaker outputs don't like to be applied to any kind of ground.  I was trying to measure the output of the amplifier using a grounded oscilloscope.  Apparently this is what was causing the amplifier to shut itself off in bridged mode.  After removing the oscilloscope from the speaker outputs today, everything is working great.  Instead of hooking the scope directly to the electromagnet inputs, I attached it to  the pick-up coil.  As I mentioned a few days ago, this a better measure of the power available for levitation anyway. I don't have time to write up everything in a classy fashion at this point, but I would ...

Measuring Magnetic Field vs. Frequency Using a Transformer

Alternating current power can be reflected by a reactive load, (like an electromagnet). Ham radio operators are familiar with this concept and measure the amount of reflected power as the standing wave ratio, (SWR). As the frequency driving a ham radio antenna is changed away from the antenna's resonant frequency, the SWR increases, less power is driven into the antenna and more power is reflected back into the radio's amplifier. On Friday, I observed that the levitation height of the superconductor decreased when the frequency of the current driving the levitating electromagnet was increased. This is the expected result based on the experience of the other teams that tried to replicate Podkletnov's experiment. However, the same behavior would have resulted if power from the amplifier was being reflected without entering the electromagnet.  The amount of reflected power is usually measured with a directional wattmeter, or with an SWR meter.  I don't have either of...

Oscilloscope Peak Via Slope

The first oscillating magnetic field superconductor levitation tests yesterday went great. With the Peavey power amplifier driving the electromagnet, the superconductor levitated at frequencies up to 164 Hz. An interesting measurement problem arose that required the use of a math trick to compensate for the limitations of the oscilloscope. Our oscilloscope has a maximum vertical range of 5 volts per division. There are 8 vertical divisions on the screen, so as long as the oscillating voltage from the amplifier is less than or equal to 40 volts peak to peak, we can read its peak value by counting divisions on the oscilloscope screen. To attain the necessary levitation force however, the oscillating voltage applied to the electromagnet had to be greater than 40 V peak. Instead of readable trace like the one shown above, the oscilliscope looked like: There aren't enough divisions on the scope screen to read the voltage. This is where the math trick comes in. We know t...

History, Ham Radio, and Touch

My dad and both of my grandfathers are masons. Consequently, as a kid, I could always find a copy of Albert Pike's, "Morals and Dogma", or a lodge monitor, full of geometric diagrams, on the bookshelf. My dad and I would talk about geometry problems like Euclid's 47th problem, the Pythagorean Theorem. Dad told a story that Euclid had proposed this problem to his student Pythagoras by sketching it in the sand while walking along the beach. Then, by drawing out a right triangle and making squares of the sides, Dd would show that the squares in the Pythagorean formula had geometric as well as mathematical meaning. The areas of squares made from the short legs of the triangle will add up to the area of the square made from the long leg of the triangle. Geometry presented as a story instead of a dry rigorous science is what held my interest as a kid and is what has piqued my recent interest in the new series "Touch" and " Daybreak " with their ...

Radiating Superconductors, Arduinos, and Data Acquisition

While doing research for the NMSU Superconductor Gravity Experiment, I came across an article published by J.E. Hirsch of UCSD . He writes that his 'hole theory of superconductivity', (more on this in a later post), predicts that x-ray photons should be emitted by a superconductor similar in size to our sample when it changes from the superconducting to the non-superconducting state. The superconducting sample I'm using cycles between states each time a set of levitation force data is taken, so I decided to go ahead and try to detect the radiation predicted by Dr. Hirsch as a side project. A Geiger counter is being used as the radiation detector because it was readily available. Data acquisition with the Geiger detector turned out to be a little more work than I expected. My first thought was that I could simply record the beeps coming from the Geiger counter and then use Audacity to analyze the resulting audio file. There were a few issues that cropped up with thi...