Homopolar Generators (N-Machine) by Bruce de Palma

[sm0ky2]

i dont think you or i could make one that was more than 80% efficient.. without precision machined parts.

even the best are less than 90 from what i understand. as most of them use electricity to create the original field, instead of magnets.
There are all kinds of losses in these things. But they are fun to play with.
it has been claimed that if you spin the disk fast enough to saturate the material. and do not collect the charge - that it will dissapate from the edges in a form of low voltage static-electric-plasma. though ive never seen this occur myself.

[AbbaRue]

A few months back I stumbled upon a website that covered the Homopolar Generator in great detail.
The site showed nice detailed drawings of different models, even showed ideas for an AC version.
I was using a friends computer at the time and didn't write down the name of the site.
I have searched and searched on google but can't find the site anymore.
Does anyone here have any idea what site it might have been.
I recall something about a long thin cylinder version being more efficient then the large diameter disk type.
I hope someone can point me to that website again.
Google has over 200,000 links, it could take a while to search through them all.

[sm0ky2]

A few months back I stumbled upon a website that covered the Homopolar Generator in great detail.
The site showed nice detailed drawings of different models, even showed ideas for an AC version.
I was using a friends computer at the time and didn't write down the name of the site.
I have searched and searched on google but can't find the site anymore.
Does anyone here have any idea what site it might have been.
I recall something about a long thin cylinder version being more efficient then the large diameter disk type.
I hope someone can point me to that website again.
Google has over 200,000 links, it could take a while to search through them all.

as far as efficiency goes the best designs use multiple disks stacked on the same rotating shaft. this forms a cylindrical shape i suppose.
depending on how the disks are interconnected/insulated will give you your actual power output, however i dont think these can achieve the high curent-bursts of the larger disks.

usually goes magnet/ disk/ magnet/ disk ect. keping the fields uniform is important. and the fields should be at least as large as the disks if not slightly larger.

also, many people use the shaft as part of their circuit,  this is somewhat limiting. based on the resistance of the shaft material. it may be better to route the inner connections on the disks upwards through the center of rotation.
hollow shafts are great for this - and out of the field before you bend off the verticle. this gives you the full potential of the center side of the disks, rather than the downgraded potential running through a metallic shaft.

[PulsedPower]

[ quote]The site showed nice detailed drawings of different models, even showed ideas for an AC version. [/quote]

AC homopolar generator? maybe you were getting mixed up with a compulsator, the site you might have been looking at is http://www.utexas.edu/research/cem/ which is the university of texas's electromechanics department, they do a lot of work on homopolar generators and compulsators, if you are interested in them go to a university library and look up "Pulsed power proceedings" the best dates were from the mid 70's to the late 80's, compulsators are more popular these days in pulsed power applications.

t has been claimed that if you spin the disk fast enough to saturate the material. and do not collect the charge - that it will dissapate from the edges in a form of low voltage static-electric-plasma. though ive never seen this occur myself.

Spun fast enough with a strong enough field it would produce a corona discharge at the rim, highly impractical but it can happen, look up magnetar (highly magnetic neutron star) for a homopolar generator on a grand scale, these things induce so much voltage in  the gas around them it ionises and they slow down quickly. Check out the field strength, over 1 billion T.

[sm0ky2]

Spun fast enough with a strong enough field it would produce a corona discharge at the rim, highly impractical but it can happen, look up magnetar (highly magnetic neutron star) for a homopolar generator on a grand scale, these things induce so much voltage in  the gas around them it ionises and they slow down quickly. Check out the field strength, over 1 billion T.

the discharge i was talking about is a low-voltage/high-current plasma, its similar to a 'corona' discharge, in fact some may argue that they are the same effect. however in a high-voltage discharge the air itself becomes ionized.

from what i understand about a low-voltage discharge - is that the disk material saturates, and emits electrons into the air.
much lower than the ionization voltage. and this charge is quickly absorbed by the air a short distance outside the perimeter of the disk.  When performed with applied electric current (rather than induced current), this occurs around the same time the metal glows red hot.  the temperature is much lower when the effect is induced - because there is no current "flow", when it occurs.