Electrical conductivity of flames (OT?)

A friend of mine has such a system. It just is not cheap. His system is a natural gas back up generator which not only powers the furnace, but also the lights , appliances, and the whole house air conditioner. The last is kind of worthwhile as he lives in the Houston area.

Dan

resonance flame detection, a thoroughly failsafe method used for years, and it does confirm what we found in the research literature about the rectification occurring at the plasma resonance frequency ( which is quite low according to these people):

We figured that we're 2 levels from the heads of state of Europe; we slightly know Lisa Schlein. I used to work with her husband Peter, physicist at UCLA/CERN... designed some CERN detector stuff for him.

Willy Brown knows everybody, like the Clintons and Obamas. We don't actually know him, but Mo knows his kid, and she once broke into Willy's Jaguar with a coat hanger.

Mo also knows a guy who used to work for Glenn Seaborg.

I've met Peter Alfke, Jim Williams, and Bob Pease, all gone now.

I met Barry Gilbert once - Analog Devices were running him around their more significant customers, and Cambridge Instruments qualified. John Larkin won't have heard of Charles Oately who pretty much invented scanning electron microscopy, and had a bunch of graduate students who made it work progressively better - I met him there and two of the graduate students, Alec Broers and Graham Plows.

EMI Central Research was more fertile ground. I met Bill Percival, who invented the Percival Distributed Amplifier back in 1936, Godfrey Hounsfield who invented the brain scanner and C.A.G. Lemay who invented the reconstruction algorithm which made it practical. I also met the wireman who wired up EMI's first colour television camera - as soon as he'd got the job done, and the camera had been shown to work, the camera was dismantled again, in stages, and photographed at a every stage, to document what he'd done. The guy was a genius wireman, but not great at documentation.

-- "For a successful technology, reality must take precedence over public relations, for nature cannot be fooled." (Richard Feynman)

True. But he answers to Barry.

I believe it is detecting the quasi random nature of the flame by measuring its varying conduction.

Well at the risk of sticking my 'plasmonic' foot in my mouth again. I think they are refering to a resonance at the plasma frequency.

But I could be very wrong. When I try putting in numbers (for the electron density) I get frequencies in the 10^9 to 10^14 range... So if the above link says that the resonance is in the kHz range... that must mean very low electron density... (like 1 per cm^3?) That seems hard to believe. But at low denisty the flame is not even be a plasma.. so perhaps the above equations don't apply. Some collective oscillation of the of the entire flame?

George H.

Flames are turbulent. If there is conductivity, it will be very noisy at low frequencies, low audio range.

low

shows a few examples with quite obvious peaks in the acoustic spectral output at frequencies up to a few kHz, but that probably has more to do with the scale of the experimental set-up than the time-scale of the processes amplifying the pressure fluctuations.