Where's Van De Graff On This Board?

[the_big_m_in_ok]

onthecuttingedge2005

why not use a Carbon mesh belt on a Van De Graaf, the Carbon Mesh has more surface area to carry a greater charge.

Sounds like a good idea to me.  But is it strong enough?  Is it prone to cracking; any kind of delamination?  Will it actually carry enough charge to be worthwhile?

@Clara  +  all others
Here's your Van De Graff discussion.
Why don't we "discuss?"  I don't know a lot about the system but there are patents.  Want to see some?  I always liked high voltage systems in general.

--Lee

[onthecuttingedge2005]

onthecuttingedge2005 Sounds like a good idea to me.  But is it strong enough?  Is it prone to cracking; any kind of delamination?  Will it actually carry enough charge to be worthwhile?

@Clara  +  all others
Here's your Van De Graff discussion.
Why don't we "discuss?"  I don't know a lot about the system but there are patents.  Want to see some?  I always liked high voltage systems in general.

--Lee

Hi Big M.

I have tons of Carbon mesh samples including Kevlar and Kevlar/Carbon fiber mixes, so long as you seal the edges of the Carbon Mesh you might not have any problems about fraying.

100% Carbon mesh is a semi conductor so it will hold a charge, I have used it in some minor Hydrogen Generator experiments.

you could buy a length of Carbon fiber and then fold it into a belt then have somebody sow the edges up real nice for you with some black thread. possibly make it with as many layers as possible.

some Carbon - Toray T300 3k is a sturdy weave, you can get tighter grade weaves than this though.

you may also want to try out some Kevlar/Carbon cross weave fiber mixes, Kevlar is a very sturdy fabric but is non conductive. you would still have to have the edges sown though.

since Carbon Fiber is used in some High Density Capacitors I think it would do very well as a Van De Graaf belt.

the Carbon mesh is flexible like cloth so it wont crack on you. it looks and feels just like jet black fiber glass cloth but its Carbon.

You would want to get thee tightest weave they have, it would be the best.

I think it would put any standard Van De Graaf and or a Pelletron to shame but it would have to be proven first.

I think cranking it up to 50k RPM's would be very exciting. I thought about using a small Fly back transformer to spray Electrons onto the belt at a faster rate but I have never done that before.

I think a Plasma fed Van De Graaf would probably be thee best you could make or get, if they even sell them that is.

Jerry

[the_big_m_in_ok]

onthecuttingedge2005 said:

Hey Jerry,
100% Carbon mesh is a semi conductor so it will hold a charge, ...  since Carbon Fiber is used in some High Density Capacitors I think it would do very well as a Van De Graaf belt. ... the Carbon mesh is flexible like cloth so it wont crack on you. it looks and feels just like jet black fiber glass cloth but its Carbon. ...

Okay, I see your points.
We used woven cloth belts for a commercial-sized lumber saw at a carpentry shop I worked at once.  To keep the belt from drying out and splitting(cotton-based material, you know), we had to smear a special grease on it to moisten it.
Your material wouldn't suffer that fate, would they?

I think it would put any standard Van De Graaf and or a Pelletron to shame but it would have to be proven first.
I think cranking it up to 50k RPM's would be very exciting.

Pretty fast.  Do regular Van De Graff's spin internally that fast?  Is there a limit?

I thought about using a small Fly back transformer to spray Electrons onto the belt at a faster rate but I have never done that before.

Wouldn't that take up so much power, the efficiency would fall?

I think a Plasma fed Van De Graaf would probably be thee best you could make or get, if they even sell them that is.

How is that different or better than a regular Van De Graff?

--Lee

[onthecuttingedge2005]

onthecuttingedge2005 said:Okay, I see your points.
We used woven cloth belts for a commercial-sized lumber saw at a carpentry shop I worked at once.  To keep the belt from drying out and splitting(cotton-based material, you know), we had to smear a special grease on it to moisten it.
Your material wouldn't suffer that fate, would they?

Carbon fiber mesh is pretty tough stuff especially if it is multi-layered and tightly woven. but then again it may wear out if the brushes or combs are not shaped right, I think I would use a Carbon roller wheel as a brush that has a light tensioner spring on it to keep it against the belt, the Carbon contact wheel might not wear the belt out so quickly.

Pretty fast.  Do regular Van De Graff's spin internally that fast?  Is there a limit?

not all spin that fast but some people do because it's all about fast charging delivery, the faster the delivery the greater charge density per second if you have an efficient way of charging the belt fast enough, Pelletrons are really fast because they are chain driven and can handle higher RPM's than standard belts.

Wouldn't that take up so much power, the efficiency would fall?

some people use the fly backs to charge the belt because it eliminates the extra comb or brush in direct contact with the belt and increases the rate of charge density on the belt faster especially if the belt is at very high RPM's.

How is that different or better than a regular Van De Graff?

Highly ionized Plasma is pumped into a circulation system that comes in contact with the top load, it offers higher density charges per second and eliminates the combs or brushes and belts all together. This kind of Plasma Van De Graaf might be a little dangerous to play with, some physics labs have them and some can be quite complex. I think the proper term would be a Plasmatron of a sort rather than an actual Van De Graaf.

it's all about partical density & acceleration per sec per second. it would be kind of cool working in a cling wrap spooling room, hair raising experience!

Jerry

[mscoffman]

A Van De Graf generator is just like a Wimhurst machine except that
a high voltage power supply injects an initial charge onto a belt.
Sometimes the high voltage supply is a Marx generator which is
multistage AC capacitors + diodes called a voltage multiplier.

Both machines then rotate the isolated charge around in the
environment and collect additional free electrons boosting the voltage
higher and higher. My feeling is that electrons should zap each other
away into freespace and if they don't, then a virtual force must be
present that allows them to collect like they do. So my feeling
is that these machines are inherently overunity in operation.

Scientific VDG machines are used to accelerate heavy ions for
studies such as formation of transuranium elements, while the the
magnetic form of accelerators is used to study details of
subatomic particles. 

My feeling is that carbon-fiber belts would not work if they are
overall conductive, since you want the charge points isolated to
build up voltage. Testatika machine used a black (probably
isolated carbon) ground plane disk because of the way charge
energy was removed by metal plates as AC rather then wear
prone brushes removing DC charge.

A Wimhurst Machine is probably better for direct energy generation
purposes because the Van De Graf generator produces extrememely
high voltages that then needs to be efficiently downconverted
to low voltage and high current for energy use.

:S:MarkSCoffman