Hardcastle/Solomon Thermionic Generator

[tinu]

@ Phil H

Before saving the planet and everything, a couple of questions about the basic assumptions you?ve made:
1. Why do you think that work function would be smaller at the edge of a rotating disk?!
2. Why do you also think that by using needles the work will decrease too?!

I suppose you don?t really have any experimental data/proof on the above (otherwise it would have been already posted on your site, right?) so, a theoretical approach will do it for me.

Many thanks,
Tinu

[Philip Hardcastle]

@Tinu

Hi,

Question 1 Answer, well the binding force on a surface electron is work function and it is electrostatic.
A force acting against the work function effective reduces the binding force. Now this as it happens was proved almst a century ago by Tolman (and was prior to that suggested by Maxwell).

The expeiments of Tolman have been scrutinised and repeated and confirmed.

It turns out from tolmans equation that the Voltage produced for 316m/sec at a radius of 1m is 5mv.

At 1000m/s (if we could go that fast) we would get 50mv.

And at 10,000m/sec it would be 5v (but no metal could stand that speed)

But just for a moment let us say we could.

If we started off with a metal of 5.15ev work function we would have reduced it effectively to 0.15 and so at room temp electrons in large numbers would escape to vacuum and in doing so do 0.15ev work.

0.15ev = 2.4E-20 Joules

Now to get a replacement electron up to 10,000m/s we would need 1/2 x 9.109E-31 x 10,000 x 10,000J = 4.55E-23 Joules

This is 1/527th of the work done by the escaping electron. Or in other words 527x over unity.

So if we had super alloy we could just do it directly, but alas we do not and so we need to essentially lever the electrons off with topography.

Q2 A.

Now the issue of work function and topography is a given. A smooth surface has a higher work function than a rough one.

As you know crowding occurs at a sharp point and if you imagine the centrifuge is pushing electrons to the tip yopu can see that the work function is being overcome by the mutual repulsion of the free electrons.

I hope this short answer helps you.

Regards Phil H

[tinu]

@ Phil H,

Hi,
Richard C. Tolman? Please post a link to the equation (and experiment) you mentioned.

Meanwhile, let?s get a step back. Some things seems very badly mixed to me. Therefore, let?s forget about rotation for a second. Assume as you wish, a 5.15eV work function. Assume the temperature you consider appropriate for your purposes. No needles. Perfect smooth surface, free of defects and contaminants. Place a sensitive ammeter in between the armature and (stalled) rotor. What would be the current resultant from thermionic emission as per Richardson? (A numeric value for current density would do it too; it would also prove the many, many orders of magnitude smaller than the one needed in a Faraday motor)
Now place a 5V battery between the armature and (stalled) rotor. What would be the new current?
Finally: What if the external battery voltage goes to 5.15V? How does it affect the current? Make it 9V.
You imply that the work function is completely overcome and thus current tends to increase toward large (infinite) values. That?s wrong. Mentioning a vacuum diode is sufficient to see your fallacy.

Waiting for your reply before moving futher.

Cheers,
Tinu

[Philip Hardcastle]

@ Tinu,

Your idea of a simple 5v battery or 9v battery is just wrong. But it is a point I made in a separate explanation as it happens because it is an easy path to blunder into.

A voltage applied is not the same as the surface potential as it is not a 5v electric field starting at the rim. That is to say the induced voltage is the displacement of the surface electrons relative to the outermost matrix.

In Tolman they used an isolated conductor (such that there were no replacement electrons) and the conductor was wound as a big coil and brought to a stop at the outside of a rotating disk. Previous attempt to just spin a disk had proved troublesome as it involved a brush which induced reading errors so they had an equivalent arrangement to induce a g force (when the coil hit an end stop).

Anyway they equated f = ma to F = Ee where m is the electron mass and e the electron charge.

This led to an equation E = L x m x a / e

The L part is interesting (note when I first had the idea I did not know of tolman and arrived at it purely theoretically) as it cancelled out by the "a", by this I mean a radius of say 1 unit gives the same result as a radius of 1/10th as for a constant tip velocity a increases while L decreases.

Please also note that the Tolman value is for an isolated system and that in a system where electrons can enter the conductor the field / voltage is much higher. This potentially means that if the system were charged the rotational velocity would reduce, however that is something that will in my opinion need a test bed experiment.

So what you have in essence from Tolman is a view of a trillion trillion electrons on springs connecting to the ion matrix and the voltage so described is related to the force in the springs.

A 5v battery connected on the centre of a stationary disk looks nothing like this, and even more so if the outer edge is not in extreme close proximity to the collector.

We all know that a smooth electrode in vacuum requires many many volts per mm of gap.

Lastly I enjoy a discussion but I would prefer if you were not quite so aggressive as to use "your fallacy".

If there is a mistake I welcome the identification of it and have in thousands of conversations with professors asked for just that. You might well find a mistake with your passion but I suggest that you could do it a bit less aggressive, after all I came here by invitation of Tak22.

That is not to say that I do not appreciate and respect your viewpoint, but don't start out by assuming me to be a fool.

Regards

Phil H

[tinu]

@ Phil H,

I have to explain myself: Fallacy in my dictionary (and in my culture) primarily means ?erroneous belief?. If you find it offensive, I deeply apologize. I have my own fallacies (everyone has) and it doesn?t make me fool; it never crossed my mind to such interpretation.

As about surface potential, I see your point as you certainly saw mine. We shall get to it as soon as I read more about Tolman. However, Faraday motor requires considerable current and I still find hard to believe that a feeble thermionic current (micro to mili Amperes, at best) is able to exert more than a totally negligible force on a massive rotor. That?s why I?ve asked for estimates. Hopefully you?ll agree that without having enough current, the device lacks the prime mover and this is a major issue, isn?t it?

Best regards,
Tinu