question about plasma headphones

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I want to ask about the corona wind type plasma,like the Plasmasonic headphones or the Nelson pass cloud speaker,I believe the Corona tweeter from Lansche is the same type,its corona discharge that is modulated push pull from both sides by electrostatic force,like a Stax but instead of membrane there is plasma.

its different from Alen Hills Plasmatronic /Magnat sphere tweeter/Ionovac,these are glow discharge that makes sound by getting bigger hotter and then cooler smaller.This is picture of the Plasmasonic headphones
plasmasonic_schematic.gif


My question is,how can this "corona wind" type plasma device work? I learned that the net charge of plasma is neutral,so how can the push pull stators push it with electrostatic force if the plasma is neutral?

When I imagined it in my head,when one stator is negatively charged,and other positively charged,wouldnt the plasma cloud go both ways?! I mean the negative charged particles in plasma cloud go in the direction of positive stator,and positively charged part of plasma goes the other way towards negative stator,my thinking is probably wrong?


Is it possible to make the plasma cloud have net negative charge instead of net neutral?
 
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PRR

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Joined 2003
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> I learned that the net charge of plasma is neutral

An equal number of boys and girls is "net gender-neutral", but in folk dancing the girls move one way and the boys move the other way.

Plasma just sitting around the room will tend to self-equalize back to a plain gas. Here we are putting energy into the gas to keep separating electrons from ions and maintain a 2-part plasma.

I believe in your picture the electrons move out from the emitter and positive ions move toward the emitter.

They show two electric drivers, so the grid signals are presumably out-of-phase. (However the Hill is wired differently.)

Then as left grid goes negative, and right grid goes positive, more electrons will flow left to right, and more ions will flow right to left. "Wind". When the audio signal reverses, the electrons and ions reverse. With reversals we have "sound".

Because the ions are far-far heavier than electrons, I would assume the sound pressure goes as the ions go.

Because it is difficult to maintain a high ionization in open air (or even in a Helium-leak), I would assume this is really say 1% ion motion and 99% air molecules bumped or dragged by the ion flow.

This is/was a real product? WOW! In my studies of ion-rockets 50 years back, the amount of thrust (air motion) was incredibly small even with dangerously high ion generator energy. But I did not think to try it bi-polar at audio frequency.
 
Hi PRR, nice analysis indeed !
I am the engineer behind the "Plasmasonic" Headphone. Indeed electrostatic pressure cannot get higher than around 1mB (milliBar) in normal air conditions (or an arc is achieved and the ionic drift region is replace by a thousand degrees electrically neutral plasma). Such a pressure can only sustain extremely light-weight devices (see for instance Saviour Lifters) but cannot be used to propel any aircraft (at least in air). However 1mB pressure is around 140dB and then well enough for most acoustic applications. Regards, Henri.
 
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Hi PRR, nice analysis indeed !
I am the engineer behind the "Plasmasonic" Headphone. Indeed electrostatic pressure cannot get higher than around 1mB (milliBar) in normal air conditions (or an arc is achieved and the ionic drift region is replace by a thousand degrees electrically neutral plasma). Such a pressure can only sustain extremely light-weight devices (see for instance Saviour Lifters) but cannot be used to propel any aircraft (at least in air). However 1mB pressure is around 140dB and then well enough for most acoustic applications. Regards, Henri.

Very cool idea!

Are these yours?

Plasmasonic
 
Easy to check, no ? (Patent + name + google)

Its an old work done when innovation in audio was still possible. After the Plasmasonic headphone, JC Fourrière from Audioreference/AHL continued to develop the technology and succeeded to make a cold plasma speaker named Toltèque using the same principle (Corona glow and electrostatic wind/pressure). At the same period most developers (Magnat, and many others) were trying to use a hot plasma version of the thermophone (exploiting electrical arcs to produce a thermal dilation of air as well explained above by Goobicii). Such thermal sources were only able to reproduce the high side of the frequency spectrum (Tweeters) whereas our technology could reproduce all frequencies and even a continuous pressure. By the way, if someone is interested, there is still no better solution other than the BUX87 to make a compact 3kV amplifier (the amplifier should by placed near the corona ion source to avoid parasitic capacitance of connecting wires), using electronic vacuum tubes is also possible but is heavy and far more hazardous to use in an headphone application.
 
All the pictures, schematics, measurement data... found on the TMMS website are genuine. Moreover I confirm that three BUX87 transistors used in the output amplifier inside each lateral side of the "Plasmasonic" headphone designed in the eighties cannot be replaced by any smaller modern device. The best present solution would be to use GaN transistors (from GaN Systems) as they are compact and have a very low output capacitance, however their peak voltage is only 650V so that more should be stacked to obtain the 3kV modulation result. Beside as they are FETs with very sensitive gate input, the driving ladder is going to be far more complex than a resistor bridge.
 
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