a thoughtful web.
Share good ideas and conversation.   Login or Take a Tour!
comment by am_Unition

I'm plasma. Which is like, the stuff that's in my blood, I think. Right?

But seriously, no one cares about plasma. It's so far removed from the human experience that it's harder to stir up excitement. No pretty pictures, basically.

Oh boohoo, whoa is me, etc.

WanderingEng  ·  2166 days ago  ·  link  ·  

I care about plasma! Plasma is why a temporary fault on a power line (a lightning strike is a common instigator) has to be cleared by disconnecting the line. The lightning is long gone, but the overvoltage it caused creates a plasma arc that is sustained by the line voltage.

Do I have that right? I'm a utility electrical engineer.

am_Unition  ·  2166 days ago  ·  link  ·  

That all sounds correct. Plasma is more conductive than Earth's gaseous atmosphere by many orders of magnitude.

I think the arc usually forms a disconnect within 10 seconds or so, because of thermal turbulence it has helped induce in the surrounding air. Problem is, you don't want a line arcing for 10 seconds, because that can really do some damage.

Does 10 seconds sound about right? Or will it go on indefinitely? Of course, it's dependent on voltage, spacing, even geometry. I guess I mean in general.

WanderingEng  ·  2166 days ago  ·  link  ·  

From the grid side, we clear a fault like that in less than a quarter of a second. It can wreak havok when a fault lingers. But sometimes they do! There's video of a fault that lasted long enough for someone to wake up at the sound of an explosion, look out the window, grab their phone and start videoing.

My experience, which mostly comes from training on "this is why we always clear faults quickly," is a fault that remains for a few seconds eventually becomes more severe. I think it's that turbulent air you mentioned. One of the three phases will have sustained plasma, and that plasma moves around and eventually the second and third phases get involved. If the first phase wasn't enough to clear the fault, the second and third ones are.

Plasma is really interesting!

am_Unition  ·  2166 days ago  ·  link  ·  

I'm typing this while my girlfriend watches, this is like my dirty talk.

Here is what she has to say: y,k6gfhu9-ewatfrdrtqyhg6f5e478huhiiiuy

Edit: we are lol'ing together. OK, now we are cuddling

Edit 2 (the morning after): Uh. Thank you for your tolerance and clarification. :)

user-inactivated  ·  2166 days ago  ·  link  ·  

    No pretty pictures, basically.

Does neon not count?

am_Unition  ·  2163 days ago  ·  link  ·  

Oh, it absolutely does! But I couldn't find the word "plasma" anywhere on that page. There's a disconnect between personal experience and scientific literacy in this instance, just like... almost every other subject. Damn.

asdfoster  ·  2167 days ago  ·  link  ·  

Very cool! Not my cup of tea personally, sounds like the worst of E&M, fluid dynamics and atmospheric science all rolled into one. But still, always cool to see another astronomer around.

But yeah, I feel you about the lack of pretty pictures. I've got some nice plots for you to ogle, but nothing of the actual planets. Just some blobby pixelated images of their host stars.

Still, the pretty stuff is cool and generates a lot of public excitement which is always nice.

Also, I wouldn't sell your field short. I'm assuming that you're studying plasma around the sun, and those CMEs and stuff can be pretty beautiful.

EDIT: I added some stuff.

am_Unition  ·  2167 days ago  ·  link  ·  

Hey now, a little bit of magnetohydrodynamics never hurt anyone. :)

See you around!

asdfoster  ·  2167 days ago  ·  link  ·  

Well, maybe not, but I'm so used to hydrodynamics as it applies to atmospheres that adding in charges and magnetic fields just seems like it would make everything so much more complicated. You're a braver man than I to tackle it. Nice meeting you!