Electrical conductivity of flames (OT?)

Got it Thanks!

George H.

I know about the conductivity of the flame, but have no idea bout this rectify property... My first guess there must be something biased... could it be

• Different metals ?

• Flame direction ? ... what else ?

So, I wonder if there's conductivity if you have two identical metal rods, symmetrically touching the two sides of the flame ...

A Theory of Resonance Rectification. The Response of a Spherical Plasma Probe to Alternating Potentials

Larkin is a narcissistic asshole... what did you expect? ...Jim Thompson

When's the last time either of you said anything technical, or logical?

I've always wondered why someone didn't come up with a natural gas powered furnace blower. Big snow storm, AC power goes out, your gas line is still intact, but you _still_ freeze :-( ...Jim Thompson

Yikes, I can see the $5000 water heater coming! Nooooo!

Depending on electrical conductivity sounds dangerous, but requiring the rectifying effect of the flame sounds much better. A bunch of conductive crud would be unlikely to replicate that phenomenon. Many flame sensors depend on sensing some component of the hydrocarbon flame, usually one of the hydrogen emission lines. But, such a sensor would need wall power, and therefore require power to get hot water. Geez, everything keeps getting more complicated. No doubt they will require computers in the next batch of water heaters "to keep us safe".

Jon

Jon

this guy built a flame triode:

Imprecisely. Hand waving.

And what about ion conduction? George's post, based on the patent, states that more current flows when the pointy part is positive.

Get a blowtorch and some pointy things and measure stuff. You can't do plasma physics by guessing.

ws

Yeah in the two symmetrical rod case there shouldn't be rectification. There's a thermal gradient as well as flame direction. And the article linked to by Fred B. implies that plasmas rectify naturally... There was an equation for the rectified current (with no explanation I could find.)

(google rectification in plasmas... or some such.)

George H.

- Hide quoted text -

robe to Alternating Potentials

Yeah I found the same thing... The other article seemed to imply that sticking a metal probe into a plasma, caused it to be biased a bit negative, and AC currents enhanced the effect... It would have been nice if he'd put a bit of the physics explanation in the abstract.

George H.

My only position is that you are making up stuff that you don't really know anything about.

detection, it seems counterintuitive, but some flame

ve

I've got some mercury wetted bi-metallic switches that control the heat in the shop and house. When the computer controlled unit in the house failed, in an emergency moment I wired in the bimetallic switch.. and never replaced the computer unit.

George H.

ionized plasma phenomenon.

None of the electron generation mechanisms I mention are purely thermionic. The thermally assisted field emission you get in an arc discharge isn't thermionic, and while you might see this with electrodes immersed in a flame, the current levels involved are way too low for a regular arc, and the flame would have to be getting the surface very close to it's melting point.

neutrality by developing a spatial potential, and this potential has to be overcome before the plasma >conducts.

Sure. You get steep potential gradients at the cathode surface in a glow discharge - the voltage gradient has to be steep enough to accelerate the ions enough between collisions in the gas phase to let them accumulate enough energy to knock off at least one electron when they hit the electrode surface. the eraly work explored this with mechanical probes.

rectifier.

That doesn't follow.

with establishing the geometry

and their resulting plasmas have been studied extensively since the early 1900s but I don't find anything on the

solve the multitude of equations representing all the physics.

And the measurement techniques got a lot more powerful - computers weren't the only technology to benefit from better electronics, initially mainly based on the superior properties of the planar transistor, which went on to become the integrated circuit. Back in

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That's my assumption. The positively charge ion distribution does fix the voltage gradient along the conductive channel at a level high enough to maintain a high enough electron drift speed to carry the current, so there must be a positive ion current as well, but it seems to be small enough to be negligible as a current carrying mechanism.