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Ask Greg Leyh of The Lightning Foundry What Charges Him Up? 88

Posted by samzenpus
from the prepare-the-lightning-cannon dept.
Greg Leyh is an electrical engineer who has spent most of his career working around particle accelerators and high-voltage machinery. Recently Leyh has been working on The Lightning Foundry, a project to see if humans can replicate the voltage economy effect of lightning. With the help of a Kickstarter campaign and a pair of 10-story Tesla Coil towers he hopes to generate man-made lightning. Greg has agreed to take some time away from his lightning machines and answer your questions. Ask as many as you like but please confine your questions to one per post.
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Ask Greg Leyh of The Lightning Foundry What Charges Him Up?

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  • by eldavojohn (898314) * <eldavojohn.gmail@com> on Monday December 05, 2011 @01:20PM (#38267824) Journal
    Your kickstarter page lists a goal of some $348,000 to do the full experiment as per your cost breakdown [lod.org]. You are now at $32,000 with five days to go meaning some of these components are not going to be affordable. Could you please explain what is being cut or if you're doing the experiment at all?
    • if you don't get successful funding on kickstarter, you get zero dollars and nobody who offered to contribute gets money. Had you read the fucking information at kickstarter, you'd know this.

      So I'm assuming funding must be coming from elsewhere.

    • Hi, If the KS campaign doesn’t reach the goal, then we’re simply back where we started. You don’t get a dime unless you reach your goal in the allotted time. You can be sure though that we'll keep working on the design, and looking for ways to score the materials. -Greg Leyh
  • What sensors are you employing to measure this lightning bolt? I don't know much about The Electrum Project or what sort of data it produced for lightning on demand so can you give us very technical details of the sensors in this experiment? Is this more a proof of concept or academic endeavor? Am I missing something on your balance sheet [lod.org] or from Electrum's site about sensors, result sets and data?
    • Electrum was primarily a lightning sculpture. However, once it was operational we took the opportunity to climb into the electrode and measure the actual base currents of the arc, since the electrode easily accommodates a person while it’s at full power. I used a Fluke 2-channel battery powered oscilloscope, connected to two Pearson fast current transformers. One CT was around a metal 'fishing rod' that I would poke out of the electrode to attract arcs. Here’s some of the waveforms we capture
      • by CnlPepper (140772)

        The polarity observation could be consistent with the relative difficulty of producing -ve streamers compared to +ve streamers. +ve streamers are generally produced at a lower E-field than -ve. It is possible you are seeing this preferential breakdown behaviour in your current results.

  • Who would you rather meet for a day and why?
  • Whats the high voltage high current switching scene like now a days? In ye olden days krytons and friends were thought to be cool, but expensive and export controlled. Now a days do you just import high voltage mosfets from China and call it good, or ...

    • For this relatively slow, high power application, IGBTs are currently the best choice. Each of Lightning Foundry towers will use an array of 4500V IGBT transistor modules made by Mitsubishi. These are typically used to run electric trains or wind turbines. At $1500 a piece, they’re by far the largest line item in our budget.
  • Aren't tesla coils continuous alternating current and Lightning an almost instantaneous pulse of direct current ? I'm wondering if those differences diminish the usefulness of this experiment.
    • by vlm (69642)

      You can send a single pulse into a tesla coil at resonant freq, err resonant period anyway, no problemo. It certainly reduces the heating problem.

      • by CnlPepper (140772)

        It also makes it do bugger all (I suspect that is what you were suggesting re "heat problem"). The whole point of running it resonant is to build up the voltage in multiple "stages". What you are suggesting would be like kicking once on a swing and leaving it at that. That'll be a boring swing!

    • Hopefully my response in 'Re:AC_DC' below will answer your question. -Greg Leyh
  • by Anonymous Coward

    Great! So generating lightning bolts from gigantic tesla coils might be more efficient if they're ridiculously gigantic instead! What was the point of this again?

  • AC/DC (Score:1, Interesting)

    by Anonymous Coward

    A Quick question: How exactly does AC electrical arcs produced by a Tesla coil help us understand the naturally occurring DC lightning produced by clouds?
    Are not the two vastly different?

    • That's a great question, and a not so obvious one! Many members here on Slashdot have noted quite correctly that natural lightning is driven by largely DC potentials, where a Tesla Coil is an AC device. However, a lightning strike actually consists of a complex series of interesting events, many of which are only 10s of microseconds in length, such as stepped leaders: http://en.wikipedia.org/wiki/Lightning#Lightning_initiation [wikipedia.org] The expected formation time of a relativistic breakdown is also on the order
  • FCC and friends (Score:5, Interesting)

    by vlm (69642) on Monday December 05, 2011 @01:34PM (#38268060)

    Short format: Are you going for 47 C.F.R. 15 sub B class A or class B? Just kidding, sorta.

    Long format: Whats your plans regarding radio interference? Like, are you making a whopping big faraday cage out of an abandoned condo building, or have a FCC exemption under some R+D rule, or ... I'm just picturing armies of angry radio listeners storming your building with pitchforks...

    • The Lightning Foundry coils won’t be a significant source of radiated power since the operating frequency will be only 5200Hz. This wavelength [about 36 miles] is *very* long compared to the tower height, so the radiation efficiency is almost zero. In addition, since the towers operate 180deg out of phase, their electric fields will tend to cancel at a distance. While operating Electrum at full power, a person viewing a TV one block away was not able to discern whether the coil was on or not by wa
      • by vlm (69642)

        My "couple kilowatt" buzz box arc welder is a couple orders of magnitude lower peak power, arc length is a couple orders of magnitude lower, operating freq is 60 hz two orders of magnitude lower, and I can knock out all radio communication for quite a distance with it... The point being that specs won't save you, design will save you, since something much smaller is much worse. So the specific electrical engineering design elements of how you make a lightning generator make ten or so orders of magnitude l

  • Have you ever been injured working with electricity?

    • I lost about 30 seconds of memory once, after touching a 5kV focus anode inside a TV set. Since then I'm especially careful, and a big fan of 'engineered safety features' such as mechanical crowbars that drop when you open a barrier to gain access.
  • by GameboyRMH (1153867) <gameboyrmh@gmail.cCOBOLom minus language> on Monday December 05, 2011 @01:42PM (#38268160) Journal

    How does your experiment differ from the SIBNIIE and HVRC long-spark experiments? [capturedlightning.com] Did you investigate the possibility of using their equipment instead of building your own?

    • The Lightning Foundry differs from SIBNIIE in that we’ll be focusing on relativistic breakdown effects, and how they might correlate with observations taken from natural lightning strikes. SIBNIIE and HVRC accomplished an amazing range of research. As I understand it, most of their research was directed towards developing Extremely High Voltage transmission lines for transporting the plentiful hydroelectric power from distant northern Siberia. I believe that SIBNIIE was the first facility to genera
  • Have you considered a large Van De Graff generator using plastic beads and compressed air?

    • Hi, take a look at my response in 'Re:AC_DC' above, and let me know if that answers your question. -Greg Leyh
  • by JohnVKaravitis (2342882) on Monday December 05, 2011 @01:45PM (#38268204)
    John V. Karavitis I'm not sure what this guy is trying to accomplish. Is this some kind of experiment into understanding the nature of lightning (don't we already understand how lightning works???), or is he trying to harness the power of lightning for commercial purposes? And what about the link that he provides, that shows a lightning discharge off of what seems like a large transformer? I think that, if someone posts an article or starts a topic thread here, we should at least be given the courtesy of an explanation. Thank you. John Karavitis
    • Hi John, The lightning initiation process still confounds experts in the field, which is understandable since the unpredictable nature and high altitude of lightning strikes effectively prohibit any close approach with scientific instruments. Several recent papers [Gurevich, Zybin, Dwyer] propose that ‘relativistic runaway breakdown’ effects might provide lightning with its amazing abilities. One conceivable way to study the lightning initiation process is to try and artificially trigger it.
  • Will you be exploring anything along the lines of the Hutchison effects (http://www.rexresearch.com/hutchisn/hutchisn.htm) - and other other odd phenomena? Or are you just sticking to lightning?
    • by nomel (244635)

      It would be great if anyone could reproduce the Hutchison effects. :-|

    • Hi, We'll be concentrating on lightning-related research, particularly effects that might explain the lightning initiation process. If we come across anomalous or unexpected effects we'll certainly explore those as well, particularly if they seem to pose a credible hazard to the machine or personnel. The possibility of running into unexpected behavior is very high when you build a machine that operates in a new part of parameter space. Most unexpected behavior turns out to be headaches; however a smal
  • What do you mean by "Voltage Economy Effect of Lightning"?!!
  • Could you explain a bit more about the possible benefits that mankind could gain from these experiments? Just for us lay-persons who don't really understand high energy physics and its associated terminolgy!
    • by vlm (69642)

      Traditionally giant lightning generators are used to develop lightning protection. For power companies, radio companies, telcos, aircraft, etc.

      1) Design and build a model or life size machine that you think will survive a lightning bolt

      2) Zap the heck out of it with artificial lightning

      3) Did blow up? If so, analyze how it failed and go back to step 1

      4) Did not blow up? Profit !!!!

      The hilarious part is watching IT guys, who never get credit for their work when IT stuff doesn't blow up, trash talk the wor

      • The hilarious part is watching IT guys, who never get credit for their work when IT stuff doesn't blow up, trash talk the work of lightning protection guys, who also never get credit for their work when stuff doesn't blow up. "Stuff still blows up sometimes anyway" "Its just a wasted expense" "Lightning never hits the same place twice / you never catch the same virus twice" blah blah blah. The ham radio guys are just as bad, ten thousand nearby strikes and no effect on system performance, one strike finally takes it out and "all that stuff is worthless no point even installing it, stuff just blows up anyway". Idiots.

        It's no "unscheduled downtime", it's a "upgrade opportunity".

        • True, for some businesses it's the ONLY upgrade opportunity.

          I wish I was kidding. The smallish company my dad works at has this sorry old Xeon server that absolutely CRAWLS. Takes 10 minutes to shut down, not kidding. The guy who runs the place is too much of a horrible cheap bastard to upgrade it.

      • by des_irl (1708908)

        Traditionally giant lightning generators are used to develop lightning protection.

        Is that what this project is aiming for, because it seems strange that a person would have to use a crowd-funding model to fund research into a health and safety issue, that one would assume the likes of G.E. or Philips or some other multi-national would be able to do much more comprehensibly?

        • by vlm (69642)

          Is that what this project is aiming for, because it seems strange that a person would have to use a crowd-funding model to fund research into a health and safety issue, that one would assume the likes of G.E. or Philips or some other multi-national would be able to do much more comprehensibly?

          I donno, but I know these facilities are expensive, and imagine where electronics would be if only G.E. could afford to own a soldering iron... or a C compiler...

        • by CnlPepper (140772)

          I'm a senior scientist in the lightning testing facility of Cobham Plc (which use to be known as Culham Lightning). We predominantly perform aerospace testing for the major european aircraft manufacturers. The aerospace lightning standards, such as ED-84, could not be practically achieved using a tesla coil arrangement. The current/voltage levels and waveforms shapes are very specific to simulate the effects of a one in a thousand (typically positive) natural lightning strike. These waveforms are easiest to

          • by CnlPepper (140772)

            *turned = tuned

          • by vlm (69642)

            True and your facilities work is valuable, but, maybe the first part of a development cycle could be done cheaply with a "zap it and sniff for smoke" methodology at a small facility.

            If your device can't survive a small scale tesla coil, no point hooking it up to a calibrated high power high expense facility like yours.

            For example, several decades ago, I pulled cable for RS-232 cables for a specific model of VAX, which was famous (at least at our facility) for blowing out its rs232 line receivers if you touc

            • by CnlPepper (140772)

              Generally, you will find that the low-level surge testing is done in-house during development, especially by the larger electronics companies. This would be the wack it, smell it test (or more precisely - measure to see if any inboard transients occur that will damage stuff you want kept alive). We cater for the higher threat level requirements where the cost of the test equipment starts to become prohibitive and the test experience is of significant value (we advise on mitigation). Even for this aspect of

              • by CnlPepper (140772)

                One thing you have to bare in mind is a lot of companies are utterly allergic to spending more money on something than they have to - they want to know they are passing the standard at minimal cost, rather than risking spending money on something that may be unnecessary - one reason all the standards have a good margin of safety. As a tesla could not meet the standard, it would not realistically be considered. A cheap LCR circuit, a charge pump and a solid state switch would cost a similar amount and do exa

  • by Baldrson (78598) * on Monday December 05, 2011 @02:29PM (#38268866) Homepage Journal
    Disclaimer: I'm a rank amateur, so be forewarned: When I was working with Paul Koloc on his erstwhile Plasmak(tm) lightning machine (when I still thought his photographs were real), I came up with a conceptually simple circuit that Paul seemed to think was (conceptually) superior to his simple (DC) capacitor discharge -- except that it was impractical given his mercury switch controls. As usual, you have to have a honking power supply charging a honking capacitor bank with a honking inductor coil ready to roll, but the trick is that at the point in the phase where the capacitor bank has been fully discharged into the inductor, you switch out the capacitor bank and replace it with the spark gap. This, purely DC system seems to better model actual lightning than AC systems doesn't it?
    • Hi, hopefully my response in 'Re:AC_DC' above will answer your question. -Greg Leyh
      • Wouldn't this simple circuit be more economical?

        For instance, if you take a few BMOD0063 P125 B04/B08 [maxwell.com]s each rated at 63F, 125V and maximum discharge current of 1,800A (energy capacity of (0.5 * [63 * farad]) * (125 * [volt^2]) ? joule = 3937.5 J) and discharged it into a 2000uH air core inductor ((0.5 * [2000 * {micro*henry}]) * ([1800 * ampere]^2) ? joule = 3240 J) might you not get the equivalent of a small car crash discharged at millions of volts by timing the switchout of the capacitor bank correctly

  • "10-story" says nothing. Are they tall stories or short stories?

  • How are you going to deal with half the population living within a 10 mile range suing you for blowing out their home electronics, and when every ham radio operator within a 1000 mile radius complains to the FCC about you ruining their radio reception?

    • by TheCarp (96830)

      Actually, not sure if the FCC can do much there. I remember looking into this when I was coiling and the advice that I always got was that the FCC bans jamming, but... radio equipment is not specifically protected from interference from the operation of other equipment. So the basic rule was that a tesla coil was "probably ok" but modulating the frequency to transmit radio signals, is certainly disallowed.

      Not sure how this would apply to a zeusaphone, which is definitely modulated, and I hear can be picked

    • by TheCarp (96830)

      Actually.... I want to expand on your liability question....and maybe scare some socks off....

      So, about 15 years ago, when I built my coil, I got to know another local coiler (I still drool over the pole transformer in his basement). At that time, he told me of an incident that he alleged happened to a friend of his. Basically, he was down in his basement running his coil, when someone upstairs smelled smoke. I don't remember much more to the middle of the story but, the ending was a bit scary....

      A sweater

    • In 'Re:FCC and friends' above, I provided a rationale for why the radiated power will be very low. Let me know if you have questions beyond that.
  • You are just looking to build the world's largest zeusaphone. I can't blame you of course, but come on, its true isn't it? If not.... you have at least considered it? Maybe play some some megazuesaphone hero?

    • Unfortunately I doubt the Lightning Foundry would be able to approach the magnificence of the Sousaphone.
  • Your web site seems to describe the goal of the project as understanding how lightning propagates as it forms and how it initiates at a far lower voltage gradient than one would expect from the ionization requirements of air, or (equivalently) jumps gaps far longer than would be expected from the voltage.

    I was under the impression that this, along with the jagged nature of the bolt, was already understood. And that it went something like this:

    - A large enough charge accumulates, producing a strong

    • One problem with cosmic-ray induced breakdown concept is that the flux of cosmic-rays required to sustain a breakdown is much greater than the amount which naturally occurs at thunderstorm altitudes. J.R. Dwyer has proposed a very novel 'positive feedback' mechanism that solves this problem using *positrons* in his paper 'A fundamental limit on electric fields in air' which can be viewed here: http://bit.ly/t0XZ6M [bit.ly] The Lightning Foundry should be able to explore a portion of the parameter space in Figure
  • Twinkle, twinkle little volt
    So far from your lightning bolt
    To your anode in the sky
    We will watch your sparkles fly

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