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Author Topic: Thermion/Photon and the Work function  (Read 13355 times)
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I've been doing some experiment on thermionic emission.

The setup consists of two plates A and B of the same metal.  Batteries in series with micro amp meter.

When heat is apply to one plate say A, high current flowing.  When heat is apply to plate B, low current flowing. No detectable current flow in the absent of electric field.
When voltage is reversed, the opposite happens.
Increasing or decreasing voltage increase or decrease current.
When both plates is heated equally, current is also being observed (with electric field).

This concludes the thermionic effect.  This experiment also post a thinking that the work function can be change by an applied electric field.  In another word, electron is easier to get ejected in an electric field vs none.

In photon bombardment
hf = W + Ke  where W is the work function
If W can be change by apply an electric field, then photon of higher wavelength can knock electron free.  I urge those with lab and high end equipment to do experiment on photoelectric to see if this is the case.  If this is true, then electron can be ejected even by photon of hf lower than the work function provided that the work function being lowered by the electric field. 





   

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Correct me if I am wrong but aren't all of your posted findings part of vacuum tube(valve) theory?


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"As far as the laws of mathematics refer to reality, they are not certain; as far as they are certain, they do not refer to reality." - Einstein

"What we observe is not nature itself, but nature exposed to our method of questioning." - Werner Heisenberg
   
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Hey WaveW, How you been.

Nah, I didn't consider this my finding, it's already there.  I just redo it to see for myself.  The only part I'm not sure about is can the work function be change.  It seems logical that we can rip electron off with just the electric field so I don't see why not.  Vacuum tube theory?  Seems like my obsession right now. lol  
   
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The work function can definitely be changed, with coatings.  Like WW said, this is vaccum tube tech, and they experimented with all this in the past.  You can google all this stuff I'm sure.

On a related note,  someone made a triode amplifier that was not in a vacuum, just over a candle flame.  Home built and very crude design but it worked.  I thought that was interesting.

EM
   
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...
This concludes the thermionic effect.  This experiment also post a thinking that the work function can be change by an applied electric field.  In another word, electron is easier to get ejected in an electric field vs none.

In photon bombardment
hf = W + Ke  where W is the work function
If W can be change by apply an electric field, then photon of higher wavelength can knock electron free.  I urge those with lab and high end equipment to do experiment on photoelectric to see if this is the case.  If this is true, then electron can be ejected even by photon of hf lower than the work function provided that the work function being lowered by the electric field.  

It's true but not free!
First note that the work function is not changed. The work function is only the minimum energy for removing an electron from the surface of a solid.
If the kinetic energy of the electron due to the heat is not enough for the electron to escape the solid, a supplementary electric field can help the electron to escape thanks to the Coulomb force F=q*E which will accelerate the electron and give it the necessary speed that the heat alone was not enough to provide.
If the electron escapes, the field has produced a work dW=F*dl to be integrated over the electron path. In other words the receiving plate tends to charge, depleting the electric field and therefore you need electrical energy to maintain it, that one used to do the mentionned work.

A better way would be a "cold cathod", which can emit electrons without any external field. Nevertheless it's not clear if it could constitute a Maxwell demon. Chinese scientists claimed to have succeeded (http://fr.arxiv.org/abs/physics/0311104), but the current was very weak and imho below the experimental error so I'm not convinced that their experiment was conclusive.

   
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How would one do an energy conservation on this set up?

Let's say we insert a load into this setup.  The energy of the load would be:

E(load) = E(bat) + heat

Notice that if the Electric field provide the energy to nullify the work function, then:

Heat = W + Ke  where W = 0

When W = 0, there is no restriction to temperature or photon frequency.
   
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It's turtles all the way down
Here is the video:

http://www.youtube.com/watch?v=FCCPeEKIVvQ

And the paper is attached.

Indeed, the current is extremely low if one need to use the input resistor of an electrometer to measure it.

Now how can this be improved upon? Is it worth the effort? Much larger plates?
« Last Edit: 2013-02-08, 16:19:37 by ION »


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"Secrecy, secret societies and secret groups have always been repugnant to a free and open society"......John F Kennedy
   
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How would one do an energy conservation on this set up?
...
E(load) = E(bat) + heat
...

Relevant remark! We should gain the part of energy coming from the heat.
Ion answered that the current is extremely low. I think so. Nevertheless the principle remains very interesting. But how to improve the effect?


@Ion

Thanks for the link. I was not aware that the Chineses continued in this way. I'm pleased that they didn't give up.


   

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Chinese scientists claimed to have succeeded (http://fr.arxiv.org/abs/physics/0311104), but the current was very weak and imho below the experimental error so I'm not convinced that their experiment was conclusive.

I believe the use of the static magnetic field to reverse the measured potential is conclusive evidence their claims are correct. Perhaps that strong magnetic field has an effect upon the measuring equipment but I have doubts about that.



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"As far as the laws of mathematics refer to reality, they are not certain; as far as they are certain, they do not refer to reality." - Einstein

"What we observe is not nature itself, but nature exposed to our method of questioning." - Werner Heisenberg
   
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I believe the use of the static magnetic field to reverse the measured potential is conclusive evidence their claims are correct.

It's only a clue of correctness, by far not enough to conclude that there is no possible flaws.

Quote
Perhaps that strong magnetic field has an effect upon the measuring equipment but I have doubts about that.

It could have effect on much more things than the measuring equipment, for instance on contact potentials between dissimilar metals, on a Seebeck effect.
The electron source could be a beta decay from traces of isotope 137 of CS in the electrodes and not from heat, and so the magnetic field would play the same role as if it was thermal electrons.
And there are surely many more other possible biases.

They say in their paper:
"the electron tube continuously extracts heat from a single temperature heat reservoir and all of the extracted heat is converted into electric energy, without producing other effect."
But it's not an exprimental evidence, it's a profession of faith. There is no temperature measurement. Their paper is surely interesting but doesn't yet constitute a proof of a Maxwell's demon, it's a beginning, it needs further investigations: a Maxwell demon must not be affirmed without experimental proof of temperature decreasing.

   
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In theory, two different metal could do it since they have different work function.  One metal would eject more electron than the other when they both submerge in the same temperature. 

http://en.wikipedia.org/wiki/Volta_potential
   
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I like the n-p semiconductor junction for this purpose,  the junction potential is around 0.6 V because of the drift of the holes and electrons across it.   So how can we get at this potential?   How about make thin slices of n-p semiconductors, that are narrow enough to be within the effect zone,  so here's the stack up:  metal, thin n layer, thin p layer, metal.

EM 
   
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I've done some additional experiment on dissimilar metals.

Top figure - when two dissimilar metal junction near each other and being heated, a high potential is observed (possibly thermionic emission).

Mid figure - when two dissimilar metal junction touch each other and being heated, a low potential is observed (possibly Seebeck effect).

Bottom figure - A possible circuit to extract heat at a constant temperature source.

   

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Quote from: GibbsHelmholtz
when two dissimilar metal junction near each other
and being heated, a high potential is observed
 (possibly thermionic emission).

Are they being heated by a flame and are they
within the flame?

Is there a minimum temperature involved?


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I aimed the flame directly at the junction so I would say they are within the flame.

I cannot determine the temperature but I would say does not direct the flame directly to the surface yields little result.

   

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Treat everyone with kindness and respect. Not because they are nice, but because you are. - Unknown
   
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No Dumped, but it gives me some idea on using bias voltage to extract gain.

My intention is to make a thermionic generator like this one:

https://www.youtube.com/watch?v=K5GVrYcjBKs

But instead using the same metal with different temperature, we could use different metal with the same temperature.  I think we can use the Schottky emission to change work function.  It's easier than finding low work function metal. 



 
   
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Have you seen this page Gibbs?

Thanks to remind me this site that I have in my favorites. I worship this kind of experimenters with unstoppable imagination and skill enough to make it real.

   

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Aye, his projects are exceedingly innovative
and creative.  And he shares his work freely.

Gibbs, whatever inspired you to research this
phenomenon?

Here are the two most informative articles I've
found on the topic.

1      

2

When properly constructed it may deliver
considerable output power.


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Treat everyone with kindness and respect. Not because they are nice, but because you are. - Unknown
   
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Just to mention a near principle as the thermionic effect, by replacing electrodes in vacuum and the work function, by electrodes in an electrolyte and the redox potential.

Vasilescu-Karpen, a physicist, published papers at the French academy of sciences during the first half of the 20th century, clearly asserting that his "battery" has no chemical reaction, that it functions with heat and contradicts the second law of thermodynamics. One of his battery is said to still work at the “Dimitrie Leonida” National Technical Museum from Romania (see http://www.greenoptimistic.com/2010/12/25/karpen-pile).

His academic papers and a patent are here (in French. I have translated the patent only, first link).
I had led some experiments on the subject before being banned from ou.com. In spite the current is weak, it is much more than by therminonic effect. In case of interest, we could open a new thread to not interfer with this one.

   
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Thanks Dumped and Exn,

I will spend some time later in the days to read the link.  What inspired me to this is the continual search to extract ambient background energy.  I read the history of Volta and his contact theory.  Seems like they had a big fight in the academic about being chemical or perpetual motion.  It was never settled.  But now we know both is correct in my opinion.  There is a chemical part and a non chemical part.  Solar and thermal is the non chemical part. 

I have to gather more parts for testing.  It'll be hard to make the desire medium between plates so I will stick with small positive result. 
Exn, feel free to post on this thread. 



 
   
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It's turtles all the way down
Thermionic and other similar converters that utilize a heat source is certainly an inviting area for research. There are many interesting papers by NASA available.

We should probably start a new thread "Thermionic Converters" and move this stuff to the class "Heat to Electrical Power Conversion" category.


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"Secrecy, secret societies and secret groups have always been repugnant to a free and open society"......John F Kennedy
   
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I've made a little interesting generator.  It consists of two diodes, a capacitor, conductor, and a piece of material.

When the conductor piece touch and release the material (I used a plastic bag), an AC current flowing.  It can also design to give DC current.  It's interesting on how electricity works. 



   
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You are charging a capacitor from electrostatic charges of the plastic sheet. This is triboelectricity.

   
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Hello Gibbs
Electrostatics was my primary area of research for many years and I have a couple of the machines I built with my kids posted on my bench. I have built many of these machines and this link--http://www.coe.ufrj.br/~acmq/electrostatic.html is the best resource I have found to date.
As well the phenomena you are experimenting with is called "Contact Electrification" and a basic description can be found here --http://en.wikipedia.org/wiki/Contact_electrification. Most of what was considered as fact for the last 100 years has also been overturned just recently --http://www.sciencemag.org/content/333/6040/308.abstract and there has been a great deal of activity in this area of science.

It is not a well know fact but the most efficient electrical generator is not electromagnetic but an electrostatic generator running in high vacuum on magnetic bearings.

In any case the science journals have set the stage for our future energy technologies and almost none of it involves moving magnets past coils of wire. The future is engineered materials which will extract ambient energy from solar, EM and electrostatic variations all at once and if this technology ever hits the required price point I think it's going to go global in a big way.

AC
« Last Edit: 2013-02-18, 18:06:49 by allcanadian »


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"Great minds discuss ideas; average minds discuss events; small minds discuss people." - Eleanor Roosevelt.

Be careful when you blindly follow the Masses... sometimes the "M" is silent.
   
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