Re: Limit on coil size

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Zoran Tukovic" <zoran.tukovic1@xxxxxxxxxxx>

Hi GL, hi All

I have some questions about TC calculations.

1.) How we can mathematically calculate impulse power of the coil ?
2.) Is it impulse power the same thing as circulating power ?

Thanx,
Tuky



----- Original Message ----- From: "Tesla list" <tesla@xxxxxxxxxx>
To: <tesla@xxxxxxxxxx>
Sent: Thursday, February 22, 2007 2:42 AM
Subject: Re: Limit on coil size


> Original poster: Greg Leyh <lod@xxxxxxxxxxx>
>
> Hi Dave,
>
> Alberta Chu has copies of Electrum available at 
> http://www.asklabs.com/electrum
>
> The physical size limit I mentioned in the talk applies specifically 
> to coils designed for generating long arcs.  If your goal is to 
> simply generate higher voltages without breakout, the coil should 
> just continue to scale.
>
> This practical limit revolves around two key features of impulse-driven coils:
>
> A)  Impulse coils take advantage of ion lifetimes to maintain the 
> arc channel integrity, until they can recharge and restrike the arc.
>
> B)  Impulse coils multiply the input power dramatically, often by 
> factors of 100's to 1000's, greatly increasing their ability to 
> strike long arc channels over CW machines.  The impulse coil is 
> analogous to a hammer, compared to a press.
>
> When increasing the size of a coil, the problem arises in trying to 
> maintain both conditions A and B, listed above.  If we set a minimum 
> acceptable value for the power gain, then our duty cycle has a 
> maximum limit.  And if the coupling is already fixed at an optimal 
> value, then the envelope represents a fixed number of RF cycles.
>
> Here is where ion lifetimes come into play.  Effective ion lifetimes 
> for coil arc channels seem to range from about 3 to 12 msec.  Many 
> coilers observe that break rates around 80-150Hz (7 to 12msec) seem 
> to yield best arc-length efficiency.  Now as the resonant freq (Fo) 
> of the coil decreases, the envelope length gets longer in time, 
> therefore the break period must also increase to maintain a low duty 
> cycle.  At some Fo the break period must increase to the point 
> (>12msec) where the dead-time between firings allows the ion channel 
> to begin dissipating.
>
> The result is that at some critical size, either feature A or B has 
> to be compromised, which would diminish the arc production 
> efficiency of the machine.  Beyond this point the coil will operate 
> in a quasi-CW, then finally a CW mode of operation.
>
> -GL
>
>
> > Original poster: Dave Leddon <dave@xxxxxxxxxx>
> >
> > I attended a most inspiring talk given by Greg Leyh last night in 
> > San Francisco in which he showed a documentary video detailing the 
> > construction of his Electrum coil (I sure would like to have a copy 
> > of that, Greg) followed by a discussion of his plans to construct a 
> > lightning laboratory in Nevada.  He mentioned that there is a 
> > physical limit to the size of a Tesla coil beyond which it cannot 
> > produce an arc due to the frequency being too low to sustain a 
> > continuous stream of ions.  I believe he said that an ion would 
> > extinguish before the next one could be generated.  Does anyone 
> > have an idea how to determine this minimum frequency?
> >
> > Dave
> > Pleasanton, Ca