Silent Van de Graaff?

[YT2095]

I`ve been thinking, since Alpha radiation is helium nuclei, Beta is electron and Gamma are photons, Alpha and Gamma are fairly useless, but Beta seems to have some interesting Potential:-)

 

if I have a conductive dome such as used in a Van de Graff, but rather than transport the electrons up into it via a belt, I had a chunk of Radium or Tritium salt inside it, it Should work, shouldn`t it?

[Rakdos]

only problem I see with this is the beta particles might be moving too fast or there not being enough of them, to get the proper effect.

[[Tycho?]]

I think you would probably need a large amount of radioactive stuff to produce the effects anything like a Van de graff generator, that is getting a charge in a reasonable amount of time. This is just a guess of course, I'm sure you'd be able to calculate the actual number of electrons you'd be getting.

 

Also you have to make sure that you'll be quite safe with regards to radiation. A metal shell will stop beta rays just fine, same with alpha. But if you get something that eventually decays to something producing gamma rays you'll be in trouble.

 

Just from checking wikipedia, I see that radium decays into radon, which is a radioactive gas and is quite toxic.

 

So while yes this would probably work, but it may not be worth the health hazards.

[YT2095]

well I was considering testing this but it seems my electroscope got lost in the move (either that or it`s still in a box somewhere) so I`ll have to make one it would seem.

 

I wonder if this can be stored in a Capacitor of some sort though, if it was a low electron count per second, a cap should accumulate this charge over time quite nicely I sumise?

[[Tycho?]]

well I was considering testing this but it seems my electroscope got lost in the move (either that or it`s still in a box somewhere) so I`ll have to make one it would seem.

 

I wonder if this can be stored in a Capacitor of some sort though, if it was a low electron count per second, a cap should accumulate this charge over time quite nicely I sumise?

 

Would it though? I thought (not like I'm sure at all) that both plates of the cap had to be part of the circuit when being charged. Little more than a guess on my part though.

[Rocket Man]

how about a dedicated cathode ray emmitter, much easier (and less suspicious than masses and masses of radioactive material).

a negatively charged spike at the bottom of a low pressure insulating tube and an anode ring near the middle and the dome at the top. electrons are stripped from the cathode, miss the anode and charge the dome.

[Klaynos]

how about a dedicated cathode ray emmitter, much easier (and less suspicious than masses and masses of radioactive material).

a negatively charged spike at the bottom of a low pressure insulating tube and an anode ring near the middle and the dome at the top. electrons are stripped from the cathode, miss the anode and charge the dome.

 

That's what I would thinking would work.

 

Doubt you could get it to do much very quickly though, maybe feel a bit funny to the touch but doubt you could get the charge to stand peoples hair on end

[Rocket Man]

it all depends on the voltage you run the cathode ray at, inductive kick back from mains ought to do something, keep one side of the coil grounded and you'll pump a fair few electrons.

[John Cuthber]

The idea of using beta emitters directly as a source of electricity does work. The currents involved are tiny but the voltage can be huge.

As for pointing an electron beam at an isolated metal sphere it sort of works but, once the sphere has the same voltage as the accelerator potential of the electron gun the electrons are repelled but the negative charge and the no more current flows onto the sphere.

You would do just as well to connect a wire from the high voltage source to the sphere directly.

[Rocket Man]

As for pointing an electron beam at an isolated metal sphere it sort of works but, once the sphere has the same voltage as the accelerator potential of the electron gun the electrons are repelled but the negative charge and the no more current flows onto the sphere.

You would do just as well to connect a wire from the high voltage source to the sphere directly.

 

that's one of the reasons i suggested inductive kickback, low current, ridiculous voltage. suppose the cathode ray was entirely inside the sphere...

no, wait, that wouldnt work either.

[5614]

I think it would work in theory, but that in reality you would get a tiny current and it would not be anything impressive.

[YT2095]

well the current was never the issue, Van De Graffs have never killed anyone at several 100`s of thousands of volts.

 

I wasn`t thinking of running Xmas tree lights off it

[John Cuthber]

The problem is that, unlike a V de G, it doesn't help you at all. You might as well use a bit of wire connected to the power supply.

With a V de G you spray charge onto a belt and the motor drags that charge towards the top sphere- in doing so it has to overcome the electrostatic repulsion between the charges on the belt and that of the top sphere. This means that work is done on the charges and their potential is raised. The current is the same as that sprayed onto the belt by the HT power suuply, but the output voltage is much higher. With an electron beam this doesn't happen so the output voltage is the same as the input.

[Rocket Man]

hmm, i hear that, triboelectrics makes a minimal constant voltage which is compounded by the belt drive.

so really the simplest alternative is a HV supply and a diode.

 

what if you use a series of coils stacked up around the stem of the van de graaf to pump the electrons up from the cathode ray and into the dome, all oscillating to apply lateral momentum which is attracted to the next coil?

 

another thought, have a single powered coil and stages of coil, diode, coil, diode, one end connected to ground the other connected to the dome. it'd work much the same as a CW but you can utilise flyback to stack up some serious voltages.

[YT2095]

*Bump*

 

another variation on a theme then, you have an open capacitor metal plate, insulator and another metal plate, there`s a wire to each plate hooked up to a meter.

 

now paint one side of the plate with a Beta emitter (that should make the Negative side), and the paint the other plate with an Alpha emitter that should make the Positive plate.

 

using the idea that since Alpha is the Helium nucleus, the neutron has no charge but the Proton does (and they have a positive charge).

 

would this work?

[insane_alien]

no, it wouldn't work. when an alpha particle is emitted it leaves behind a negative ion since the electrons don't suddenly disappear.this side would, overall, be neutral.

 

some goes for the beta side, the emission creates both an electron and a proton. there is no change in charge. overall, it would be neutral too.

[YT2095]

it seems I need to make myself another sensitive Electroscope (no idea what happened to my old one???).

[John Cuthber]

I think insane alien is mistaken. It would work. The alphas would plough into the other plate and charge it + while the electrons left behind would charge the alpha emmiting plate -. The same goes for the betas (the other way round). In fact, you only need one source.

[kanzure]

While this is still on topic, let me link over to this page that details the construction of van de Graaff generators as well as many other subtopics. Also, there's the page on the simple homemade van de Graaf generator-- you may have to acquire a taste for soda since the design is slightly dependent on the packaging cans.