Like many people, going through university followed an intense career building period was a dry spell in terms of making things. Of course things settled down and I finally broke that dry spell to work on what I called “non-conventional propulsion”.
I wanted to stay away from the term “anti-gravity” because I was enough of a science nut to know that such a thing was dubious. But I also suspected that there might be science principles yet to be discovered. I was willing to give it a try anyway, and did for a few years. It was also my introduction to the world of high voltage… DC. Everything came out null though, meaning that any effects could be accounted for by some form of ionization or Coulomb force. At no time did I get anything to actually fly, though there was a lot of spinning things on rotors or weight changes on scales and balances due to ion propulsion.
So when a video appeared in 2001 from a small company called Transdimensional Technologies of a triangle shaped, aluminum foil and wire thing called a lifter that actually propelled itself off the table, I immediately had to make one. I’d had enough background by then to be confident that it was flying using ion propulsion. And in fact, given my background I was able to put an enhancement in my first version that others came up with only later.
For those who’ve never seen a lifter, it’s extremely simple. Think of it as a very leaky capacitor. One electrode is an aluminum foil skirt, in the shape of a triangle. Spaced apart from that around an inch or so away, usually using 1/6″ balsa wood sticks, is a very thin bare wire (think 30AWG) also shaped as a triangle. High voltage is applied between the foil skirt and the wire. The result is that a downward jet of air is created around and through the middle of the triangle and the lifter flies up off the table. But that is just the barest explanation of how it works. We must go deeper!
Continue reading “Expanding Horizons With The Ion Propelled Lifter”
Working with high voltage is like working with high pressure plumbing. You can spring a leak in your plumbing, and of course you fix it. And now that you’ve fixed that leak, you’re able to increase the pressure still more, and sometimes another leak occurs. I’ve had these same experiences but with high voltage wiring. At a high enough voltage, around 30kV or higher, the leak manifests itself as a hissing sound and a corona that appears as a bluish glow of excited ions spraying from the leak. Try to dial up the voltage and the hiss turns into a shriek.
Why do leaks occur in high voltage? I’ve found that the best way to visualize the reason is by visualizing electric fields. Electric fields exist between positive and negative charges and can be pictured as electric field lines (illustrated below on the left.) The denser the electric field lines, the stronger the electric field.
Weak and strong electric fields
Ionization in electric fields
The stronger electric fields are where ionization of the air occurs. As illustrated in the “collision” example on the right above, ionization can happen by a negatively charged electron leaving the electrically conductive surface, which can be a wire or a part of the device, and colliding with a nearby neutral atom turning it into an ion. The collision can result in the electron attaching to the atom, turning the atom into a negatively charged ion, or the collision can knock another electron from the atom, turning the atom into a positively charged ion. In the “stripping off” example illustrated above, the strong electric field can affect things more directly by stripping an electron from the neutral atom, again turning it into a positive ion. And there are other effects as well such as electron avalanches and the photoelectric effect.
In either case, we wanted to keep those electrons in the electrically conductive wires or other surfaces and their loss constitutes a leak in a very real way.
Continue reading “Wrangling High Voltage”
In high voltage applications involving tens of thousands of volts, too often people think about the high voltage needed but don’t consider the current. This is especially so when part of the circuit that the charge travels through is an air gap, and the charge is in the form of ions. That’s a far cry from electrons flowing in copper wire or moving through resistors.
Consider the lifter. The lifter is a fun, lightweight flying machine. It consists of a thin wire and an aluminum foil skirt separated by an air gap. Apply 25kV volts across that air gap and it lifts into the air.
Lifter flying with high voltage power supply
So you’d think that the small handheld Van de Graaff generator pictured below, that’s capable of 80kV, could power the lifter. However, like many high voltage applications, the lifter works by ionizing air, in this case ionizing air surrounding the thin wire resulting in a bluish corona. That sets off a chain of events that produces a downward flowing jet of air, commonly called ion wind, lifting the lifter upward.
Continue reading “High Voltage Please, But don’t Forget the Current”
[Steven Dufresne] of Rimstar.org is at it again with another very functional science experiment. This week he’s showing us how he made a large electrostatic motor, also known as a Corona Motor.
A Corona motor makes use of a cool
phenomenon called the Corona discharge, which is the ionization of a fluid
(in this case, air) surrounding a conductor that is energized. He’s done other high voltage experiments that take advantage of this, like his Ion Wind propelled Star Trek Enterprise!
The motor works by using an even number of electrodes on the motor, each electrically charged; positive, negative, positive, negative, etc.
Because each electrode is the opposite charge, they want to repel each other — but since the cylinder is electrically insulated, the charges have no where to go — instead the cylinder begins to rotate as the charges attract back and forth — when a positive charge on the insulation meets a negatively charged electrode, the charge is removed by ionization (creating the corona effect), and the cycle continues. The direction of rotation is determined by the angle of the electrodes. The motor can get going pretty fast but doesn’t have that much torque or power.
Continue reading “Funky Looking Motor is Powered by Static Electricity”