Exploring the Uses of Helium, Krypton, Argon & Neon in Incandescent Bulbs

In summary: Krypton is harder to come by and it costs more to extract, so it makes sense that the cost would be higher.
  • #1
Facial
30
1
I have a question about helium :

If it is the most inert substance, why isn't it used more than krypton or argon for high-temperature incandescent bulbs?

I don't see neon in light bulbs too often either.
 
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  • #2
Helium can diffuse through a thin glass wall, so it would escape from a light bulb (not very useful).
 
  • #3
What would the color be with helium?
 
  • #4
Would it matter? The OP was about incandescent, not fluorescent bulbs.
 
  • #5
Helium is also much harder to ionize.
 
  • #7
It might have something to do with heat capacity. High temperature instruments like ICPs use argon as the cooling gas because it can hold more heat than helium can (and take the heat away).
Might also have something to do with cost. Does helium cost more than argon or krypton?
 
  • #8
rachmaninoff said:
Helium can diffuse through a thin glass wall, so it would escape from a light bulb (not very useful).

I suppose, then, that it can probably diffuse through a thick glass wall, but I'll have to look that up sometime with regards as to how much slower.
 
  • #9
Facial said:
I suppose, then, that it can probably diffuse through a thick glass wall, but I'll have to look that up sometime with regards as to how much slower.
I did an experiment testing this last year. It turns out that effusion rates are proportional to molar mass (Graham's law?). If helium has a molar mass of something like 4 and krypton is way way up there in terms of mass, that's a considerable difference.
 
  • #10
Graham's law explains the relation between molar masses on the rate of diffusion. It should be the the inverse square root of the molar masses if I remember correctly, meaning Helium diffuses roughly 3.2 times as fast as argon (turns out that it has around 40 daltons of mass).

However, I need a reference on how 1) composition 2) thickness affect diffusion rates as well.
 
  • #11
ShawnD said:
Does helium cost more than argon or krypton?

For argon the answer must be yes. The atmosphere is about 0.7% argon (which is quite a bit if you think about it) by volume, meaning you can distill this gas right out of the air. The cost definitely makes sense here.
 

1. How are helium, krypton, argon, and neon used in incandescent bulbs?

These gases are used as fillers in the bulb to prevent the filament from burning out too quickly. They help to regulate the temperature inside the bulb and keep the filament burning at a consistent rate.

2. Which gas is the most commonly used in incandescent bulbs?

Argon is the most commonly used gas because it is inexpensive and readily available. It also has a high thermal conductivity, making it effective at regulating the temperature inside the bulb.

3. Are there any differences in the uses of these gases in incandescent bulbs?

Yes, there are slight differences. Helium is the most effective at increasing the lifespan of the bulb, while krypton is better at producing a brighter and whiter light. Neon is often used in colored bulbs for decorative purposes.

4. How do these gases affect the energy efficiency of incandescent bulbs?

These gases do not directly affect the energy efficiency of incandescent bulbs. However, they do help to regulate the temperature inside the bulb, which can impact the overall lifespan and energy usage of the bulb.

5. Are there any drawbacks to using these gases in incandescent bulbs?

One potential drawback is that these gases are not as effective as other methods, such as LED technology, in improving the energy efficiency of bulbs. Additionally, some of these gases, like krypton and neon, are more expensive than argon, which could impact the cost of the bulbs.

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