MOVING SOON TO: http://amasci.com/tesla/heli1.html FIX YOUR LINKS! VACUUM-LESS PLASMA SPHERE SECRET (fm Ed Harris, usa-tesla discussion) *************************************************************** * After hearing about a rumor that "Eye of the Storm" plasma * * spheres use high pressure helium, Ed Harris experimented * * with tesla coils and nobel gases. The rumor is true! * * A box or balloon full of pure helium or argon will give * * immensely long snakelike discharges! * *************************************************************** People in the past have used Tesla coils for powering plasma globes since they need high voltage high frequency currents to work. Tesla himself experimented with them in the form of the carbon "button" bulbs. If you can build a discharge chamber, it allows you to get many times the arc length of a standard air discharge coil. In some high pressure plasma experiments, people have, in the past, sometimes added helium gas to raise the working pressure of a plasma discharge -even up to and beyond 15psi. I have tested this idea recently with a homemade plasma sphere run from a small 15kHz flyback supply. I can obtain 15psi discharges in helium with some small partial pressure of air(or other gas) with rather small input from the flyback (est~5Kv). So yes! You can run a plasma sphere at atmospheric pressure with helium + small dopant gas. -Ed Now if I can only find some reasonably non-toxic gas which produces nice colors! -Ed Harris EDHARRIS@MPS.OHIO-STATE.EDU Well- some guy remarked previously about using a plastic bag or the like as a atmospheric pressure plasma sphere. So I accepted the challenge :) I was able to make a plasma sphere using a rubber balloon which was very well purged of air (air partial pressure approximately 1/1000 atmospheric pressure) and filled with helium. Powered by a 10kV flyback circuit, the arcs inside the balloon could be seen to extend from the central electrode all the way out to the rubber (about 5 inches). Hope some others try this It's rather neat! -Ed Harris EDHARRIS@MPS.OHIO-STATE.EDU Date: Sat, 12 Aug 1995 11:51:29 -0700 (PDT) From: William Beaty To: list physics teaching Subject: Rubber ballon plasma sphere At one atmosphere!!! How about sealing a rubber glove to a largish balloon, stick a hand inside, and let plasma play on your fingers? Got a good camera? Should be good for an Omni magazine cover! And how about an entire room with an He atmosphere? Such things must exist somewhere. If a *glassless* plasma globe unit was taken into one, wouldn't the plasma filaments extend right out into the air? And what would happen to colors and filament structure when small bags of various 1-atm gases were released in such a room? Or if a handheld unit was moved through various gas layers in a glovebox chamber? Or hold your breath, go inside, touch a larger tesla coil terminal, and see if humans can serve as plasma globe electrodes. If the leads to a neon-sign transformer were connected across a large volume of He, would a "beam" of red plasma leap between them? If so, what would happen if you poked at the plasma beam with a glass rod, or tried to cut it with a glass sheet? Could a plasma-ball supply and a UV laser be used to create a *real* Star-Wars movie lightsaber effect inside a large He-filled chamber? Mind boggling. The physics demonstrators sure are going to have fun with this one! - Bill Beaty, billbeskimo.com MORE STUFF Ed Harris discovered that pure Argon works even better than Helium, giving bright white snakelike discharges like those seen in various Plasma Globes. I experimented with this and found that Nitrogen (air) wrecks the effect, so if you try an Argon Balloon Plasma Globe, you need to flush all the air out. Do this by squeezing out the balloon, filling it part way with Argon, allowing the argon to all leak out, then filling the balloon all the way. If a metal rod or coathanger wire is pushed up into the balloon and the balloon neck is sealed with cable ties, you've got yourself a quick and dirty glassless plasma globe! It only lasts a few hours though, before air diffuses through the rubber and wrecks the effect again. I messed with the argon gas in a large plexiglas cube. Argon is a bit heavier than air. If you fill a box slowly with argon from the bottom, and provide an exit hole at the top, the box will fill up slowly, and you can obtain long, snakelike discharges near the bottom of the box as the slightly-heavy argon drives the air upwards. The same tesla coil terminal that gives inch-long discharges in air will give foot-long discharges in Argon. Pretty cool to move the tesla coil terminal wire to different places in the box and watch the discharge grow from dim, purple corona to blazing snakes many inches long. If you build a plexiglas box, be aware that the fumes from plexiglas solvent or from silicone caulk will pollute your argon. Let your box dry for a couple of days before working with the argon. Oh, the industrial grade argon obtainable in welding tanks for about 70$ recharge cost works just great. An Argon+CO2 mix didn't work.