If nothing else, [Justin Atkin] is persistent. How else do you explain a five-year quest to create sonoluminescence with simple tools?
So what exactly is sonoluminescence? The short answer is as the name suggests: a release of light caused by sound. In [Justin]’s case, he used an ultrasonic transducer to set up a standing wave at the resonant frequency of a flask of water. A drop of water is used to entrain a small air bubble, which is held in a stable position in the flask in much the same way as styrofoam beads are in an acoustic levitator. Turn off the lights and you’ll see that the bubble glows with a ghostly blue light.
What causes the glow? Good question. According to [Justin], we just don’t know for sure what causes it, although the leading theory is that cavitation of the bubble causes the trapped gas to compress and heat violently, turning into a brief bit of plasma. But there are problems with that theory, which is one of the reasons he wanted to show just how easy the process can be – now that he’s shaken out the bugs with five years of effort. It wasn’t easy getting the transducers attached and the driver circuit properly tuned, but with little more than a signal generator, an audio amp, and a spool of magnet wire, you too can make your own “star in a jar.”
We applaud [Justin]’s determination to bring this project to a successful conclusion. It’s not unlike his dogged effort to make a cold plasma torch, or even his desktop radio telescope.
Continue reading “Capture A Star In A Jar With Sonoluminescence”
It’s no secret that a vast amount of American infrastructure is in great need of upgrades, repairs or replacements. The repairs that are desperately needed will come, and they will come in one of two ways. Either proactive repairs can be made when problems are first discovered, or repairs can be made at considerably greater cost after catastrophic failures have occurred. As was the case with the I-35 bridge collapse in Minnesota, we often pay in lives as well. Part of the problem is that infrastructure isn’t very exciting or newsworthy to many people outside of the civil engineering community which leads to complacency and apathy. As a result, it’s likely that you may not have heard about the latest struggle currently playing out in California even though it involves the largest dam in the United States and its potential failure.
Surprisingly enough, the largest dam in the US isn’t the famous Hoover Dam but the Oroville Dam at the base of the Sierra Nevada mountain range in California. At 235 meters, it is almost 15 meters taller than the Hoover Dam. It can store over four cubic kilometers of water but whether or not it will keep storing that water into the future is currently under question. In February of this year during a flood control operation damage was observed on the dam’s spillway where a massive hole had formed which only got larger as the dam was forced to continue releasing water. The hole quickly grew, and the floodwaters eroded much of the lower half of the spillway embankment, forming a canyon. Continue reading “Another California Water Crisis”