betas o' joy, or direct nuclear electricity

[icedragonw1]

Fun, my inner scientist has found himself a new idea to latch onto.

It started when I was watching the Google tech talk on thorium fluoride reactors, and while my inner scientist reversed engineered the whole thing and found out it was a bad KISS (keep it simple stupid) and said “if you used molten lead you could keep the solid metal fuel assembly, make it a fast breeder reactor, and even use the whole ‘frozen plug’ idea that make the liquid thorium reactor meltdown proof” there’s more to that, but that’s not what I want to talk about

My inner scientist loves fringe ideas, and he found one in betavoltics ( I think I spelled that right).

Well here is the thought, if you punch thorium in the face with a neutron it turn into proactium *that’s not spelled right either I think, oh well* and then that proactium gives off beta particles, or more commonly known as electrons.

These are not you pusansy electrons *they go photosynthesis-meow!* these electrons have a couple of MeV (mega electron volts) under their belt and move about the speed of light (or as fast as Einstein says they can) and well move towards the nearest positive source at said near SOL (speed of light). Creating a current.

Well thorium already is a metal, so if you connect a wire to a piece of thorium being irradiated and give it a positive terminal (which to that accumulation of a charge is basically anything) would you get a current?

Thinking about it, the current could be insanely large if you just had large chunk of thorium being irradiated by regular old Uranium-238. the U-233 after said fun betas o’ joy could simply keep the reaction going.

[drmike]

Since you start neutral, you end neutral. You can't have a current if you can't store the charges in different states. The electrons eventually have to come back to the ions that they came from, so you need to separate them and create a battery. The distance an electron can travel in metal is really small, so that's pretty darn hard to do.

Look up "electron stopping distance" for the materials you have in mind. Then figure out how you would set up the materials to create your battery.
I'm not saying it won't work - but I will say it's pretty darn hard.

[icedragonw1]

the now U-233 is positively charged after it gives off a electron in beta decay? I had the assumption that it would be in fact neutral still after giving off betas, but that would make sense from what I found.

back to square one for my inner scientist (though he is already trying to come up with a solution)

[drmike]

Right, it's no longer U-233, it's Np-233. The electron came from a neutron that changed into a proton, and the electron doesn't stay in the nucleus because the strong force doesn't affect it. (Do a web search on "strong nuclear force" and "weak nuclear force" - it'll be fun!)

[icedragonw1]

well that idea got blown out of the water, thanks for the facts! (challenges make for a interesting puzzle especially right now that I sliced my hand and rather bored for a few days while it heals, just a few stitches)

however,
round two:
if you let the electrons hit a metal plate (such as aluminum) it creates a negative charge on the metal plate, and the now Np-233 will be positive and wanting it's electron back like a just broken up relationship (guess they just needed a breather)

if you connect the metal plate and the radioactive metal, wouldn't the electrons flow through the wire and create a current? I know the limitation is that it might just be easier for the electron to jump back the way they came and a insulator wouldn't work. The best solution would be simply to give them space. Making for a bulky, but very long lived and slightly powerful battery.

[icedragonw1]

well that idea got blown out of the water, thanks for the facts! (challenges make for a interesting puzzle especially right now that I sliced my hand and rather bored for a few days while it heals, just a few stitches)

however,
round two:
if you let the electrons hit a metal plate (such as aluminum) it creates a negative charge on the metal plate, and the now Np-233 will be positive and wanting it's electron back like a just broken up relationship (guess they just needed a breather)

if you connect the metal plate and the radioactive metal, wouldn't the electrons flow through the wire and create a current? I know the limitation is that it might just be easier for the electron to jump back the way they came and a insulator wouldn't work. The best solution would be simply to give them space. Making for a bulky, but very long lived and slightly powerful battery.

[drmike]

You are on the right track. The problem is the stopping distance for electrons. You need really thin layers of U-233, insulator and good conductor. There are really good models for how electrons slow down in matter, so we can compute just how thin those layers need to be. Then you have to figure out how to fabricate it so it will be rugged enough for the application you have in mind.

Gillette built a razor blade because he didn't know it was impossible for the technology of the time. There's a lot about materials we still don't know, so you might be able to build this doing something nobody else ever thought of.

[icedragonw1]

wow, that is a new record for my inner scientist

15 minutes and he solved it, of course it wasn't that hard with the ultimate research tool and almighty time sink

teh internet!

so a U-238 doped thorium metal emits electrons and these great number of electrons will go through a Diode

a diode is the simplest semiconductor and it fits the bill perfectly.

for those who have don't know how said diode works, it basicly a one way valve for electrons. No photocell needed.

so as the electrons go through said diode. they want to get back through to their now positive friends. the diode will allow them when it's connected by a wire and creates a current for us to make the electrons do whatever we want them to do. like power our computers to make funny stories online.

Thanks for the help drmike!

[Aero]

You are on the right track. The problem is the stopping distance for electrons. You need really thin layers of U-233, insulator and good conductor. There are really good models for how electrons slow down in matter, so we can compute just how thin those layers need to be. Then you have to figure out how to fabricate it so it will be rugged enough for the application you have in mind.

Gillette built a razor blade because he didn't know it was impossible for the technology of the time. There's a lot about materials we still don't know, so you might be able to build this doing something nobody else ever thought of.

Do you mean that he could make something like a capacitor with U233 sandwiched between aluminum? The Alpha battery analysis showed that the best theoretical energy that could be recovered from the fissions was 50% from a large parallel plate configuration (large plate area), but I didn't see any analysis of a capacitor type of configuration. My simple mind says near 100% for that configuration. They used a charged grid to keep the electron back scatter in check.
Sorry, I don't have the link handy but has its own thread on this forum from maybe August 2008.

[drmike]

Right, a self charging capacitor is another way to describe it.

But heat and radiation damage are factors that have to be dealt with, so it is not a trivial problem.

[KitemanSA]

so a U-238 doped thorium metal emits electrons and these great number of electrons will go through a Diode

Now you got ME totally confused. By what mechanism would U238 doped Thorium produce betas? Either you have a Thorium isotope that will beta decay by itself (in which case, why the U238) or you have one that doesn't so you need nuetrons to convert it to Protactinium which beta decays... (in which case why the U238 since U238 is VERY stable and decays by alpha decay). What am I missing here?

[icedragonw1]

oh, sorry i didn't realize that U238 was not a neutron emitter. so really to simplify the whole idea is use a beta emitter and cover it in a diode and cover that in a metal like copper then cover that in a electrical insulator. connect a wire to the beta emitter and the metal and the electrons will travel (with great speed) through the wire, and create a current.

[drmike]

The idea behind the circuit is ok, but you need to think of the stack of materials as part of the circuit. Set up the surface between insulator and metal to be the diode, and set up the beta emitter to be the electron source on the other side of the insulator (or diode).

It's like trying to understand microwave circuits using isolated components of resistors and capacitors. It won't work. The whole system is the whole circuit. A resistor is really a capacitor and coil and resistance all rolled into one, and the solder that wicks up on the edges of the resistor are part of a cavity that can radiate. Same thing with your beta emitter battery. The energy source, insulator and conductor have to become the circuit you want simply by putting the materials next to each other. Not so easy to do, but it might work!

[MrBill]

I'm a newbee to the forum, so please be gentle.

Battery aside, could this be a way to replace the electrons that leak out of the well? Recirculation not being 100%, it would be easier to have a beta producer replace the lost electrons rather than inject them. It's been 40 years since I worked in this kind of stuff, but I seem to remember that the force is BXV -- the electrons would be effectively trapped by the magnetic field and quickly lose energy from that acceleration. Would they then join their cousins in the cloud, contributing to the anode?

[hanelyp]

The same magnetic field to slowed electron flow from the plasma to the grid would get in the way of electrons boiled off from the grid making it into the plasma.