The video above is one of the final products from research done on electrostatic winds. While exploring all aspects of electrostatic winds, the major focus for that semester was finding new methods and techniques to visualize the winds created. The brilliant green you see is the result of liquid nitrogen and a laser to see a cross section of what is happening. During our work at SUNY Oswego we developed several different techniques for visualizing and studying this impressive phenomenon. The following steps give an overview of ways you can recreate the winds generated with a strong power supply. The same concept can be applied in many unique ways, you are encouraged to develop your own spin on this work.
Step 1: What in the Science Is Going On
Electrostatic wind goes by many names. Ionic wind, electric wind, or my usually favorite corona wind. The main driving force behind this concept is a high voltage source and an air gap between that source and ground. Another term for voltage is potential difference. When potential difference between the high voltage and the ground are strong enough the air around the set up will ionize. A thin wire or needle helps concentrate the ions. I try not to worry if we are gaining or losing electrons because with electricity it is all convention between positive and negatives. I like to think of it as the electrons want so badly to get to ground that they actual travel through the air. The diagram shows just the opposite but does it really matter? That is it in a nut shell. High voltage ionized the air, the air moves towards the ground collector and a wind is created.
Step 2: Different Ways to Set Up
Overall I find this to be pretty simple in practice. You will need a way to SAFELY produce a high voltage. Every set up is different but we started seeing this effect around 15,000 Volts. Most of the set ups we use were able to reach as high as 25,000 Volts where the wind generated was stronger. Anything above that voltage we would actually get a spark of electricity across our gap and no wind is generated. we used an old Spellman DC power supply which allowed us to adjust the voltage.
The second image shows the most basic set up. The pins at the top are connected to our high voltage around 20kV. The aluminum foil is used as our collector and is connected to ground. We actually just tied a wire to the sing in the lab we worked in. The wind would travel from the pins towards the ground plate and then continue on downward. The third image shows a similar set up but we used a thin wire instead of pins. both are fine the main idea is make sure they are pointy pins or really thin wire for best results. The last image shows a diagram of the set up used in the video at the top. it is essentially the same but we curled it around to a cylinder shape. I designed it so we can adjust the number of pins and the distance of the air gap. so besides just visualizing the winds we were also looking to optimize the amount of wind and look for trends.
Step 3: How to "See" Wind
Do to the high voltage we were not able to get very close to the set up. It was a constant struggle not put my hand in there to feel the wind which seemingly came out of thin air....a little punny? we were able to read the current from our power supply and try to use that as a representation of the wind speed. It was less than satisfying so we developed this liquid nitrogen method to see our results. The apparatus was flipped upside down and place on a flask. liquid nitrogen is in the flask and when we add water, lots of that smokey effect was produced. there is a wide angle laser attached to the ceiling. this produces a plane instead of a point. Now we have a cross section of laser light illuminating the vapors coming our of the flask. Add a very dark room and a nice camera and you can see the wind move.
Step 4: Other Uses
Now that you are thoroughly amazed, your mind should travel to what else can i do with ionic winds. One use that we see currently is electrostatic fans. Those blade-less fans are one example but there are more serious uses. Super computers can generate a lot of heat. This type of wind can be used to more air and keep the computer cool with out any moving parts. This can similarly be used to make different types of pumps and filters. There is potential for drones and other types of flight but there are some major limitations. The video shows our hexalifter that uses the same properties to float in the air. That set up is made of balsa wood and weighs around 15 grams. 20kV to lift 15 grams is not a great ratio to get a human off the ground. besides generating enough voltage you need to be connected to a ground. This makes flight difficult and is the reason the hexlifter is attached to the table. The next video shows a clever setup that causes the middle the spin. Same concept, the pins are connected to high voltage and the outside foil is connected to ground. Please apply your own spin... to the examples shown.