Re: Power versus Spark Length
From: Greg Leyh[SMTP:lod-at-pacbell-dot-net]
Sent: Sunday, July 13, 1997 10:46 PM
To: Tesla List
Subject: Re: Power versus Spark Length
John Freau wrote:
> Recent work with disruptive coils, and old work with tube coils, suggest
> that the power required for a given spark length follows (more or less) a
> simple direct square law.
> Two coils were built, each optimized for its input power level. One drew
> 680 watts and gave a 42" spark, the other drew 2100 watts and gave a
> 65" spark. The tube coil results followed a similar trend.
> watts (wallplug) spark length
> 10.6 5 1/4"
> 42.6 10 1/2"
> 170 21"
> 680 42" (actual)
> 2100 65" (actual)
> 8400 134"
> 33.6 kW 268" (22 feet)
> 67.2 kW (30.8 feet)
> 134.4 kW (44 feet)
> 537.6 kW (88 feet)
Your curve appears to fit amazingly well to a number of widely spaced
data points, both empirical and calculated.
Two data points that I compared to this curve:
watts (wallplug) spark length
28.5kW ~22' TC in Austin TX, with improved primary ckt
5.1 MW 270' From design set for a twin 85' coil system
This squared relationship makes sense if the following statements are true:
A) The arc's current density remains constant as the current increases.
B) The arc's total consumed power is proportional to its volume.
C) The arc can be modeled as a long thin cone, where its base diameter
is proportional to the square root of its length.
D) The arc length is proportional to the output voltage.