How do flame christmas lights (the ones that mimic candles) produce their effect?

Hello bakegoodz and thank you for your question.  

The type of Christmas lights you have described are sometimes known as
"Flicker Flame Lights":
http://www.christmas-decorations.ws/decoration/7-c7-flicker-flame-lights.php

A description of how they work is below:

"Flicker flame bulbs have two pieces of metal cut into the shape of a
flame and placed close together in a bulb filled with neon gas. They
produce an irregular orange glow which flickers and looks something
like a candle flame, only slightly pinker. The CA-5 bulb is slightly
smaller and narrower. We placed them in a 65-unit fixture, where they
make a cool (or cheesy) 'haunted castle' effect. The bulbs are
somewhat temperature dependent and about 10% stopped working and
another 10% sometimes work and sometimes do not after 6 months. I
don't mind the effect as a real candle might 'blow out' too, but if
you have a smaller fixture or you need them all to work you may want
to order 20% more than you actually need to compensate for the high
'burn in' failure rate"
http://www.lightinguniverse.com/products/view.aspx?family=2084

"Technique - Neon flicker bulb
This flicker bulb is actually a small gas-discharge tube, filled with
neon gas. The envelope of such bulbs is usually flame-shaped. Looking
closer, you can see inside, where the filament of an incandescent lamp
would be, a pair of flat parallel plates, cut out in the shape of a
flame.
These lamps are available with standard-sized screw bases, and smaller
candelabra bases, but in all cases, the actual light-up part is small
- usually 3 Watts.
When energized by 110VAC, the lamp lights with a characteristic orange
neon glow, with the light dancing on the surface of the plates.
These lamps are likely to be found at home improvement stores, like Home Depot. 
The salient points of this design are: 
This design is intended for use on 110VAC, and is not suitable for battery power. 
The flickering light inside the lamp has a distinct orange color,
characteristic of neon. The color is very un-candle-like."
http://wolfstone.halloweenhost.com/TechBase/flktch_FlickerTechniques.html#NeonFlickerBulb


Thank you for your question, and If you need any clarification of my
answer do not hesitate to ask.

Very best regards

THX1138

Search strategy used:
Flicker Flame neon 
://www.google.com/search?hl=pt&ie=UTF-8&oe=UTF-8&as_qdr=all&q=+Flicker+Flame+neon+&btnG=Pesquisa+Google&lr=

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Request for Answer Clarification by bakegoodz-ga on 04 Dec 2003 11:42 PST

I didn't see anything about how they flicker, regular neon bulbs are solid.

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Clarification of Answer by thx1138-ga on 05 Dec 2003 08:44 PST

Hello again bakegoodz

To actually find an explanation as to what causes the flickering
effect proved to to be very tricky indeed, and took me about three and
a half hours in the end, but at last I have found the answer :)

"The flicker effect is caused by the ionization of neon gas between the
two "flame shaped" electrodes.  The needed potential is based on the
pressure of the gas and the spacing of the electrodes.  Convective
currents cause the climbing effect just as in a Jacob's ladder.

When the neon fires, there is a current flow from one electrode to the
other. Less potential is needed to keep the gas ionized once the lamp fires.
The net effect is that there is not enough potential to ionize all the gas
in the plate area thus creating the flicker effect.

Have you ever noticed how a flickering neon panel lamp generally comes
on solidly when even a small amount of external light is applied?  Think
quantum mechanics!"
http://groups.google.com/groups?hl=en&lr=&ie=UTF-8&oe=UTF-8&threadm=1998082703151700.XAA29323%40ladder03.news.aol.com&rnum=2&prev=/groups%3Fq%3Dfilaments%2Bcandle%2B%2Bflickering%26hl%3Den%26lr%3D%26ie%3DUTF-8%26oe%3DUTF-8%26selm%3D1998082703151700.XAA29323%2540ladder03.news.aol.com%26rnum%3D2

Very best regards

THX1138

The researcher really come through on the clarification. Good job!