How fast is turning air into plasma?

[DragonEmperor23]

"...Air molecules simply couldn't get out of the way anymore and so instead they were torn apart. At that speed, pretty much anything was devastating, and the ride we'd taken Malkuth on especially so. In its wake, the air had turned to plasma and high-energy wavelengths had filled the air, blasting everything around us mere moments before the fireball itself. The path of destruction we'd wrought, along with the massive crater that had been pounded into the earth, had reshaped the battlefield yet again, adding a massive, elongated crater to the existing one while slagged everything around us."

How fast would this be?

 

[Crimson_Azoth]

Hypersonic

 

[Andytrenom]

Hypersonic is simply catching on fire through speed, this is something else. Although I'm not sure what rating it will be.

 

[Crimson_Azoth]

Fire is plasma, so...

 

[Andytrenom]

It is?

 

[Andytrenom]

Either way, hypersonic is about setting yourself on fire not making the air around you go through a state change so I'm not sure if it's still applicable here.

 

[DragonEmperor23]

bump

 

[Ogbunabali]

Fire is not plasma, that's very incorrect.

As for how fast they would need to move, it depends. The best I could find is this.

 

[Crimson_Azoth]

Fire is not plasma, that's very incorrect.

It's not?

I need to go chew out my chemistry teacher now

 

[Ogbunabali]

No, it's an oxidation reaction. In order to turn into plasma it would need to be very, very, very hot and I'm pretty sure it can't happen on it's own.

 

[Crimson_Azoth]

Thanks! About time I learned that!

 

[DragonEmperor23]

bump

 

[Antoniofer]

We already discussed about this, plasma is not an specific phenomena like lightning, but rather an state of matter (something involving ionization, I'm not the most knowledge in the subject), so it do not have a set speed.

Perhaps in order to ionize the electrons moves at particular speed, not sure, but the same apply to elevated temperatures, the faster the molecules move, the higher temperature is the environment.

 

[Agnaa]

Couldn't you reasonably find the speed needed so that the air drag experienced to be hot enough to turn the air into plasma?

I'd expect that this wouldn't be possible under SoL (hell, it might not be possible even if we grant FTL) so I'm not sure how reliable using physics estimates for this is.

 

[Antoniofer]

Simple heating wouldn't be enough, ionizing have to do with the losing or addition of electrons.

 

[DontTalkDT]

No, it's an oxidation reaction. In order to turn into plasma it would need to be very, very, very hot and I'm pretty sure it can't happen on it's own.

Burning is an oxidation reaction, not the flame itself.

Here is an article that shows the electrical properties of a candle flame. Or here a video if you prefer.

Doesn't really have to be all that hot to be a plasma.

 

[Andytrenom]

@Dont But normal flames are still not plasma right?

 

[Ogbunabali]

Flames are colorful gases that result from a chemical reaction. And you do need to be pretty damn hot if you want to turn normal fire to plasma. Considering you need the electrons to be least to be 15.6eV hot in order to ionize nitrogen.

 

[DontTalkDT]

See article I linked above.

Normal candle flames are plasma.

 

[Ogbunabali]

I mean if it reaches enough temperatures it may ionize the particles, and candle flames contain "partial" ionized gasses, they're not like 100% plasma. And like this and this point out, most of the time fire isn't plasma.

 

[DontTalkDT]

100% ionized plasma is a rare special case. Something can be a plasma with less than 1% ionization.

I could throw more sources around, but ultimately the opinions on this might differ. Reason being that the definition of plasma isn't exact. If we go by the Debye length characterization, the definition just is that it has to be short, but, as far as I know, without specifics where the border is exactly.

A candle flame is probably a rather borderline case.

 

[Ogbunabali]

I know I didn't mean it literally.

Yeah I think we have to agree to disagree. Because I don't think having such a small ionization would be enough to qualify for plasma.

 

[DragonEmperor23]

Is the math on this accurate? I found it while googling.

 

[DontTalkDT]

It sounds somewhat plausible, but I really don't know.

Would be High Hypersonic.

 

[DragonEmperor23]

I see, thank you.

 

[XING06]

Eh I know the Navy Railgun that fires at around Mach 7-ish? generates a short plasma trail (not sure if it's the air though - could be part of the rails).

Also, Hypersonic+ reentry speeds from spacecraft definitely converts air to plasma . You don't need High Hypersonic.