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Hey what is the most conductive gas that can be easily found. and will lowering the pressure increase the conductivity?

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    \$\begingroup\$ I don't think you're going to find any conductive gas until you ionize some of its components. At which point it becomes a plasma, rather than a gas. \$\endgroup\$ – The Photon May 4 '16 at 16:44
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    \$\begingroup\$ at which time it will emit photons - how ionic. \$\endgroup\$ – JIm Dearden May 4 '16 at 16:47
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    \$\begingroup\$ Thermally, electrically, acoustically, what??? \$\endgroup\$ – EM Fields May 4 '16 at 16:48
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    \$\begingroup\$ physics.stackexchange.com/questions/38631/… \$\endgroup\$ – JIm Dearden May 4 '16 at 16:54
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    \$\begingroup\$ I'm voting to close this question as off-topic because it is off topic \$\endgroup\$ – placeholder May 4 '16 at 17:35
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In answer to part 1 of your question:

  • Argon is readily available (check welding supply centers) and has about 1/5 the dielectric strength of air.
  • Helium, also fairly available, has about 1/6.5 the dielectric strength of air.

In answer to part 2 of your question:
Yes, reduced pressures generally reduce the dielectric strength of gasses.

(note: Lower dielectric strength = less barrier to conductivity & once a gas's dielectric is "broken," the resulting arc creates a highly conductive plasma)


Further Reading:

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  • \$\begingroup\$ But it should still be pointed out that: Gasses are not conductive in the traditional sense. They don't really conduct at all until you hit the dielectric breakdown voltage, then they become REALLY conductive real fast, they also emit light at this point. \$\endgroup\$ – Sam May 5 '16 at 2:06
  • \$\begingroup\$ @Tom ...and are technically converted from gas to plasma rapidly between corona-discharge phase & arc phase, at which point they cease being gasses & are converted into plasma. However, I don't think that's immediately relevant to EE discussion unless making a corona->arc sensing or triggering device (such as components of the arc/plasma speakers I'm currently designing circuits for). \$\endgroup\$ – Robherc KV5ROB May 5 '16 at 7:14
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Gases have extremely low electrical conductivity, all of them. This is because they are basically a vacuum with "a few" electrically neutral molecules in it.

When you ionize such molecules by some mean (e.g. increasing the temperature) you obtain what is called a plasma, which you can imagine as gas made by ions and electrons.

In particular, if you have a gas container with electrodes in it, and you apply a voltage above a ceratin value, called breakdown voltage of the gas, you can ionize the gas (this technique has many applications in electrical engineering and applied physics).

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