How do regular 120 volt (night light) NEON bulbs burn out?? The neon
gas is sealed in a glassbulb, and an electrical charge runs though the
gas.   After several years, usually 8 to 10, the neon bulbs start to
flicker and fail.   Why do the neon bulbs fail?

Neon bulbs consist of electrodes encased in a glass bulb with a
phosphorescent gas. When you apply a high voltage to the electrodes,
the neon gas ionizes, and electrons flow through the gas. These
electrons excite the neon atoms and cause them to emit light that we
can see. Neon emits red light when energized in this way. Although
commonly referred to as "neon" lights, these bulbs may contain other
gases instead, and so they are also called electric discharge lamps,
or vapor lamps. Other gases emit other colors. For a list see:
http://library.thinkquest.org/27356/t_neon.htm?tqskip1=1&tqtime=0722

Both the electrodes and the excited plasma that creates light
deteriorate over time.
http://science.howstuffworks.com/question293.htm

Search Strategy: neon light bulb +deteriorate

Nellie Bly
Google Answers Researcher

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Request for Answer Clarification by sueska-ga on 23 Jul 2003 18:16 PDT

Yes, as hedgie-ga indicated I was seeking more of an answer to the
following - What exactly takes place in the bulb that causes the
deterioration?

Neon gas leakage around seals sound possible. 

What would cause the deterioration of the electrode? Heat?? Doesn't
quite sound right since neon bulbs run cool.

Also how would the excited plasma deteriorate?  Is it possible that
the neon gas looses electrons to the point of not emitting the photons
of light? If so does the neon gas change to another substance by
loosing those electrons?

Thanks all

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Clarification of Answer by nellie_bly-ga on 23 Jul 2003 19:02 PDT

Sueska--

I'm sorry but I feel your set of questions is a bit beyond the range
of a $2 query.
I encourage you to check Google Answers' Pricing Guidelines:
http://answers.google.com/answers/pricing.html          
         
"$2 - $5  
  ·  Can be answered with a single link or a single piece of
information. Sometimes, if a researcher is personally interested in
the question's subject, they may provide a longer answer.
  ·  Not appropriate for multipart questions."  

Also, please note that I believe hedgie's information refers to
fluorescent rather than neon bulbs.

The reasons why plasma might deteriorate would depend on a multitude
of factors and would vary with the specific type of gas.  As pinkfreud
points out, a likely cause of bulb failure is also a damaged seal.

Electrodes also deteriorate for a variety of reasons including
fluctuation in voltage, moisture and comtaminants in the gas.
See http://www.noblelight.net/pdf/10_LampLifetime.pdf  for a
discussion of this.

Nellie Bly

Thank you nellie_bly-ga (hedgie-ga and pinkfreud-ga) for your answers.
Yes, I will definitely followup on the links and do additional
research. I am giving a presentation on the Google Search Engine,
Services, and Features soon. "Google Answers" will receive high
reviews!
Yes, I realize I tested this question to the limit, please note that a
tip has been added. :) Your answers give validation to the fact that
the three of you are Researchers with high ratings.

Also, a tiny break in the seal can cause the bulb to lose its neon and
become nonfunctional:

"Neon has no filament, like a regular bulb. Neon glows because
electric current activates the neon gas. Neon bulbs have no
'lifespan.' The main reason neon bulbs stop working is because the
neon gas will leak out if a seal is damaged."

http://www.pcmods.com/faq.asp

Why all of the above is true, the main cause of the 
deterioration was not highlited. These lights do have
filament, which heats up, not to produce light like in
incadescent bulb but to help emission of electrons.
 
You can see the filament here:
http://science.howstuffworks.com/fluorescent-lamp2.htm

Sueska 

Re:
What would cause the deterioration of the electrode? Heat?? Doesn't
quite sound right since neon bulbs run cool

   Sometimes the truth is stranger then fiction: The electrodes
   are heated and coated to facilitate the emission of electrons.

  The coating evaporates (by sublimation)
   and filament  eventually burns out.


  Of course, they may be other processes. Leaks, as Pinkfreud
  suggested, are possible, particularly if you break the glass :-)

  The plasma does not deteriorate. It is created fresh each time
   you turn the lamp on. Plasma is unstable at the room temperature,
which
   is temperature of the gas and of the glass -  That is what you feel
   when you touch the tube.

  Plasma is maintained by the electrons,
   bumping into the neon atoms, 
   atoms  get excited and emit light ...

So - the process is:

  older or cooler electrode or less electric field --> less electrons
  Less electrons - less plasma -> less light

  As  nellie_bly-ga correctly pointed out, if you want to argue 
  and get more evidence, you may have to repost at higher price,
  or you can read about the tubes yourself:


The History of Vaccum Tubes or Electron Tubes
 ... In 1904, John Ambrose Fleming invented the first practical
 electron tube called the
 'Fleming Valve'.
 In 1906, Lee DeForest invented the audion later called the ... 

Radio Hall of Fame - Dr. Lee DeForest, Pioneer
 ... of wireless communication. In 1906, deForest invented the
three-element
 electron tube, calling it the audion. Unlike the "diode ... 
www.radiohof.org/pioneer/leedeforest.html

 In the triode (electron tube) you can actually see the glowing
cathode
 as the glass is clear (uncoated).

 It was an interesting chapter in history of physics, stretching
from Edison, deForest, Roengen (cathode rays).. nglish physicist Sir
Edward Crooks and so on

SEARCH TERMS
 deForest, triode, Crooks
inventors.about.com/library/ inventors/blvacuumtubes.htm

Detailed description of the aging  process is contained in the 
following article:
http://www.ecmweb.com/ar/electric_rf_lighting_tunes/

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