# [TCML] Voltage - Flame

Paul Nicholson tcml88 at abelian.org
Sat Jan 28 14:31:37 MST 2012

```James Zimmerschied wrote:

> 2) the theoretical voltage on the top terminal is stated to be
> dependent on the radius of curvature of the top load

Yes,

> - however spherical top loads do not produce the longest sparks.

Yes, too.

There is no contradiction here.

The radius of curvature determines the breakout voltage, but
I suggest the capacitance of the topload is a significant
factor in determining the length of the arcs, once the voltage
reaches breakout level.

Hence, given a sphere and a toroid with same radius of
curvature, they will break out at the same voltage but the
toroid will throw the longer arcs by virtue of its greater
capacitance.  The sphere has the smallest possible C for a
given radius of curvature, so arguably is the worst shape for
throwing long arcs, which is why it is used for HV terminals
in situations where you want to contain the charge on the
electrode.

Conversely the toroid is a good shape for throwing long
arcs because we can increase the capacitance (major diam)
while leaving the breakout voltage fixed (minor diam).
With the two diameters to play with, we have to some extent
independent control of the two factors.

As for flames, I didn't notice any - just robust responses to
a bad idea.   The bad idea is that arc length provides a
measure of terminal voltage.
--
Paul Nicholson
--
```