Re: Natural streamer :)

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "davep by way of Terry Fritz <twftesla-at-qwest-dot-net>" <davep-at-quik-dot-com>


>>>>     When I run my "big" [18" sparks, but only 35 microamps short-circuit
>>>>current] VDG everything within several feet stars to show visible
>>>>discharge.  If they sharp points are close there isn't much voltage
>>>>rise.  If I approach it with my hand I'm liable to get zapped, but if I
>>>>hold a pin in my hand [pointed toward the terminal, of course] and
>>>>approach nothing much happens.  Same phenomenon.


>>>Wait a sec!!  Your VDG can give 35uA but can only give an 18" spark??

>>        Spark length, esp. for a DC DC machine, as van de Graaf,
>>        is mostly voltage related.  Voltage of neither
>>        machine being stated...


>I'd modify that to say "voltage gradient related", since the breakdown
> voltage of the upper terminal is set by the radius of curvature.

	Hmmmmm.  I guess....

> Of course, in my case, it's limited by breakdown from base to terminal.

	Concur.

> If you have an easy way to measure the terminal voltage of a

> large VDG I'd be interested to know it.

	'easy' is a relative term...
	I have a couple of pro HV Research Engineering books
	with whole chapters theron.  Whether 'easy' applies
	to any of those techniques is up for discussion....

	An old article on van de Graaf construction included
	building a longgggggggggggggg string of hi meg
	resistors, driving a uA meter, with the other side
	grounded.  By use of MANY resistors, the breakdown
	voltage was distributed...  Use of a uA meter kept the
	van de Graaf in its normal operating mode.

	May be something wrong with that, but I can't think
	what....

	best
	dwp

...the net of a million lies...
	Vernor Vinge
There are Many Web Sites which Say Many Things.
	-me