Physics of Lightning Hack Chat

Custom lightning, made to order

Wednesday, March 31, 2021 12:00 pm PDT Local time zone:
Hack Chat
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Greg Leyh will host the Hack Chat on Wednesday, March 31 at noon Pacific.

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Of all the things that were around to terrify our ancestors, lightning must have been right up there on the list. Sure, the savannahs were teeming with things that wanted to make lunch out of you, but to see a streak of searing blue-white light emerge from a cloud to smite a tree out of existence must have been a source of dread to everyone. Even now, knowing much more about how lightning happens and how to protect ourselves from it, it's still pretty scary stuff to be around.

But for as much as we know about lightning, there are plenty of unanswered questions about its nature. To get to the bottom of this, Greg Leyh wants to build a lightning machine of gargantuan proportions: a pair of 120 foot (36 m) tall Tesla towers. Each 10-story tower will generate 8.8 million volts and recreate the conditions inside storm clouds. It's an ambitious goal, but Greg and his team at Lightning on Demand have already built and demonstrated a 1/3-scale prototype Tesla tower, which is impressively powerful in its own right.

As you can imagine, there are a ton of engineering details that have to be addressed to make a Tesla tower work, not to mention the fascinating physics going on inside a machine like this. Greg will stop by the Hack Chat to answer our questions about the physics of lightning, as well as the engineering needed to harness these forces and call the lightning down from the sky


Physics of Lightning HackChat Poster - SVG version (Rev 1.01)

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Physics of Lightning HackChat Poster - SVG version

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  • Hack Chat Transcript, Part 1

    Dan Maloney03/31/2021 at 20:05 1 comment

    Greg Leyh11:46 AM
    Hey all

    HI Greg, welcome!

    Lightning Phil11:46 AM
    Used to work in a lightning test lab. Here's 100kA going through a piggy bank - - I miss smiting things.

    Poor piggy

    Greg Leyh11:47 AM
    Was that filled with copper?

    Thomas Shaddack11:47 AM
    Got what it deserved for working in finance.

    Thomas Shaddack11:48 AM
    How many joules in that pulse?

    Lightning Phil11:49 AM
    Yes, copper coins. Attempted a comedy sketch with the other tech working there, where we needed to smash the piggy bank after running out of tea and needing the funds. Probably good for the world that it's long lost as acting skills are at a minimum :O)

    All of them?

    Darrin B joined the room.11:49 AM

    Lightning Phil11:50 AM
    About 60 kJ

    Lightning Phil11:51 AM
    Very low circuit resistance and inductance though

    Thomas Shaddack11:51 AM
    Whoa, that's quite a ka-pew. Voltage?

    Ingineer joined the room.11:51 AM

    Lightning Phil11:52 AM
    Max charging voltage was 60 kV - That lab was in Cardiff. There's another in Abingdon with much more energy

    Greg Leyh11:52 AM
    For reference, here's an onion passing just 30kA.

    Thomas Shaddack11:52 AM
    and any special measures like coaxial cables or waveguides or other high-frequency shenanigans to get the rise time shorter?

    Lightning Phil11:53 AM
    Never zapped food as the mess is hideous - and I'd be the cleaner...

    The smell...

    Lightning Phil11:54 AM
    Just low inductance transmission lines. About 400mm wide with a 4mm gap filled with PTFE sheets

    Lightning Phil11:54 AM
    The guys in Boeing's test facility in Seattle used their kit to tenderize steak

    Thomas Shaddack11:54 AM
    any special design of the capacitors? (my high-freq-fu is weak...).

    Lightning Phil11:55 AM
    It worked, but they didn't find all of it - then there was a little smell

    Thomas Shaddack11:55 AM
    I saw somewhere a Marx generator to make shockwaves to break rocks into their component grains.

    Lightning Phil11:55 AM
    Yes, very low inductance GAEP capacitors with coaxial resistor assemblies and a coaxial spark gap

    Greg Leyh11:55 AM
    @Thomas Shaddack Yeah, Schlumberger has a rock fracturing rig like that, in a mobile truck.

    scubabear11:56 AM
    @Greg Leyh Hiya Greg!

    Greg Leyh11:56 AM
    Hey SB!

    scubabear11:56 AM
    @Greg Leyh Ready for some embarrassing questions?

    Greg Leyh11:57 AM
    There are no embarassing questions, only embarassing questioners. ;>

    Lightning Phil11:57 AM
    Hey Greg!

    Thomas Shaddack11:57 AM
    I wonder how difficult it'd be to make homemade low-inductance caps like these. Ordinary caps are easy(ish).

    Greg Leyh11:58 AM
    @Thomas Shaddack Those are usually wound in class 10 clean rooms.

    Lightning Phil11:58 AM
    Not at Norfolk Capacitors - grumble

    Drake Anthony joined the room.12:00 PM

    scubabear12:00 PM

    OK, looks like it's time to start. I'm Dan and I'll be the mod today along with Dusan as we welcome Greg Leyh to the Hack Chat. We're going to talk lightning today, what it is and how to make your own.

    Welcome, Greg! Can you tell us a little about how you got into the physics of lightning?

    scubabear12:00 PM
    @Greg Leyh Remember this bitchin diode you gave me 35+ years ago?

    fcathers72 joined the room.12:00 PM

    I read that as "Bitcoin diode"...

    Bob joined the room.12:00 PM

    Greg Leyh12:00 PM
    @scubabear Oh yeah, wow... Been making any HVDC with it?

    scubabear12:01 PM
    Listening now about the best ways to do that!

    Greg Leyh12:01 PM

    Ingineer12:01 PM
    Sadly Bitcoin probably needs thousands of diodes that size just to power all the mining rigs.

    Nicolas Tremblay joined the room.12:02 PM

    Greg Leyh12:02 PM
    Maybe ask @Drake Anthony how to with the most prompt radiation possible.

    dprice joined the room.12:02 PM

    reece20beck joined the room.12:02 PM

    Greg Leyh12:03 PM
    @Dan Maloney For many years I’ve been intrigued by how lightning seems to defy classical electrical theory. Storm clouds can start an arc discharge with only 5-10% the voltage you would need in the lab using some unknown trick, possibly involving relativity.

    My goal now is to build a machine...

    Read more »

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babaLou wrote 03/31/2021 at 19:15 point

Looking forward to Greg's presentation

  Are you sure? yes | no

Doug Borge wrote 03/31/2021 at 19:01 point

Greg, first thank you for sharing your knowledge. I am excited to listen to your conversation. The hottest lighting stikes on earth are about 30,000 Kelvin (53,540 ºF). What is the temperature of your recreated lighting at the 1/3 scale coil and what is the expected your taller model at 120 ft. (36.5m). -Douglas from Tesla Science Center at Wardenclyffe. 

  Are you sure? yes | no

James Van Damme wrote 03/30/2021 at 01:02 point

Um, a Tesla tower generates AC, right? Why not use a van de Graaf generator or some such to generate DC, to simulate lightning?

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