Ned Simmons wrote:

(...)

That's a pretty remarkable claim -- that, at least in the range where
a normal lamp operates, the current flowing thru a filament is
completely independent of the voltage applied to it.

Your model shows a net reduction of voltage available to the bulb.
In the experimenter's case, the amount of voltage to the bulb remained
the same but it was distributed differently in the filament eg. a 'hot spot'
area dissipating significantly more power than it had before it was thinned.

I said that the positive temperature coefficient of the filament would tend
to limit the change of the current through the bulb as the power distribution
in the bulb was changed by thinning some portion of the filament.

Your numbers show that the variation in current through your bulb was
about half the variation in voltage across the bulb. A one volt change
across the bulb caused a 2 milliamp change in current. This is the
nonlinear positive temperature coefficient variation I was on about.

Had that PTC effect not been in place, we would expect to see a 5 milliamp
change in current for a 1 volt change. A new current equilibrium was
established that was within 0.35% of the pre-modification current, under
a voltage change of 0.82%.

(...)

Then I'm not sure what you're claiming.

I'm not claiming much of anything.

Their claim, IIRC is that one can make a light bulb universally 'better'
by exposing it's filament to laser light, because the resulting roughened
surface somehow causes it to convert electrical power into visible -
frequency photon emission more efficiently than does the smoother
un-modified filament, without changing the cross sectional area
of the filament anywhere along it's length.

I don't deny that you can shift the average color temperature of the bulb
upwards towards blue without increased bulb power by thinning the filament,
but I do deny that the effect is produced by anything other than
merely thinning the filament.

I also deny that laser beam exposure 'improves' the bulb because it will
significantly decrease the amount of time that the lamp remains functional
as compared to it's lifetime had it not been exposed.

A bulb design that fails significantly more often than average is not a
better design. It is a worse design even if it is more efficient during
it's short stay in the socket.

That the researchers have
convinced their peers at a major research university, the Air Force
Office of Scientific Research, and the referees at Physical Review
Letters, but not you, that blasting material off a filament with a
laser is a significant achievement?

Blasting material off a filament is a parlor trick, not a significant
achievement.

I believe Mr. Guo and Mr. Vorobeyv are mistaken at best.

--Winston

--

We now return you to the economic collapse, already in progress.