Most people have a rough idea about what plasma is, usually thanks to the plasma TV craze that hit many years ago and has since been replaced by LCDs, but few will know that plasma is actually one of the 4 fundamental states of matter right along side solid, liquid and gas. The transition between a gas and a plasma is done through a process called ionization/deionization which converts the gas into an electrically conductive cloud which can be done by either inducing a large voltage difference or by subjecting the gas to extremely high tempreatures. The following video shows the latter and is a rather cool demonstration of the transition process.
The short run time for sustaining the plasma cloud is simple, given enough time that superheated cloud of carbon atoms would start to melt the pyrex container which would free the plasma to wreck all sorts of havok on the microwave itself. I’m not sure how long it’d last though as it looks like the atomised carbon atoms need to be cluster together for it to work, hence the spool up time require to set up the initial plasma reaction. Indeed if my experiments with bananas are anything to go by (it’s relatively safe but still, I’m not going to recommend you do it) you’d instead get little flashes rather than the sustained cloud.
What really interested me was the hum that was generated as it was pretty regular and I couldn’t really figure out what would be causing it. As it turns out there’s actually a couple things that could be responsible and, interestingly enough, the frequency could change depending on the input frequency of the power source going to the microwave. That link also suggests another, similar experiment with cut in half grapes that’s supposedly a lot safer (although this site argues otherwise) and the results look very similar to my results with bananas. It seems there’s all manner of things you can use to create plasma in the microwave, something I didn’t expect.
This is one of those experiments that I reckon would be really great for class demonstrations (this is probably also the reason why I shouldn’t be allow to teach science in schools but come on, fire and explosions are awesome!).
One of my university lecturer’s had a reputation for talking for hours on end about his previous projects (Dr John Rayner if you’re interested). This wasn’t atypical of many of our lecturers since the majority of them had spent many decades in industry or research before becoming lecturer’s, but Dr Rayner was a curious exception to those who were just being a little nostalgic. He was a physicist turned engineer, which is strange because even though we share some common ground most of us would never think of “crossing the border” as it were. As such we routinely had him sub in when either of our physics or engineering teachers were absent and it was guaranteed that his class would somehow revolve around one of his previous projects. The twist was, even though we’d always think we were just wasting our time listening to him by the end we all understood the material we needed to be taught, even though he rarely delved into the theory required. One of the most interesting lessons we got from him was on the expectations of customers and how that will influence your designs.
He was working on a community housing project in one of the northern states and one of the concerns was water usage. They’d optimized basically everything apart from the toilets so it was left to him and his team to optimize the amount of water that they used. They had then designed a system that used around a tenth of the water of a conventional toilet, a considerable saving. However after passing initial testing (using an IEEE approved analogue for human waste, basically sausage skin filled with sawdust) they then sent them along for their real world exposure. Curiously whilst no one reported any problems actually using the toilet they weren’t well received. As it turns out the perception of so little water being used made most people feel uneasy about the toilets, thinking they hadn’t properly flushed or that they weren’t clean. Thus the design was reworked, although he was coy on the actual results.
This whole lesson came steaming back when I saw this article yesterday:
Researchers have demonstrated a prototype device that can rid hands, feet, or even underarms of bacteria, including the hospital superbug MRSA.
The device works by creating something called a plasma, which produces a cocktail of chemicals in air that kill bacteria but are harmless to skin.
The team says that an exposure to the plasma of only about 12 seconds reduces the incidence of bacteria, viruses, and fungi on hands by a factor of a million – a number that stands in sharp contrast to the several minutes hospital staff can take to wash using traditional soap and water.
The first thing that sprung to many people’s minds is how this could be used to eliminate the need for washing your hands. It’s an interesting idea since the use of this technology could be quite a bit more hygienic whilst saving water and towel waste. However whilst novel and indeed an elegant alternative it will take many years for such things to replace the norm, just because people won’t feel comfortable walking out of the toilet without washing their hands.
It’s a challenge that every engineer will face when they’re designing and building a new system. There are a lot of social and technical norms out there and going against them won’t do anything to help the adoption of your product. I think this is the problem that Google Wave has faced recently since it has melded so many different technologies (and therefore expectations of how it will function) that we’re no quite sure how to go about using it. The fact that it has no real physical analogue doesn’t help the matter either, and that’s why my Wave account sits unused for the better part of a month.
So it becomes the engineer’s challenge to understand the everyman and work with him, since they will become the ones using our creations. I used to look upon this as unnecessary rework but over time I grew to appreciate the familiarity that came with certain lines of products (thank you Microsoft ;)) making learning and utilizing them to their fullest so much easier. A good understanding of your users can be as valuable as a good understanding of the solution, and I’m forever thankful for the eccentric Dr Raynor for teaching me that.