The 'voltage economy' mentioned above occurs during the stepped leader phase, which is very low current compared to the return stroke. High current arc discharges at the laboratory scale fair no differently than low current ones; the current only occurs after the initial breakdown phase, so it cannot be a factor. Seriously, if you think you have a valid answer for this, you should publish.
Each tower will require up to 1.8 megawatts of AC prime power. The most economical AC power choice would be the local power grid. However, if the Lightning Foundry is required to operate in a remote area or if the local power authority cannot handle megawatt transient loading, then there are two options for generating the AC prime power: A) An gas turbine-alternator set or B) A stand-alone diesel generator. Option A is preferred over B, since a turbine set is considerably more compact and is easier to transport. If we’re not able to score an affordable turbine set or secure a robust connection to the power grid, then leasing a 2MW Diesel generator set is the remaining option.
Hi Ralf,
That interview was interesting [got to visit the amazing Google campus] but unfortunately it was completely unrelated to the Lightning Foundry. It involved something considerably more practical than pure research. I'm pretty sure there wasn't a video.
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
The Lightning Foundry should be able to explore a portion of the parameter space in Figure 2, and a good part of the 'Semi-stable' regime in Figure 3.
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 small percentage of these become discoveries. When we brought up the 1:12 scale Lightning Foundry prototypes for the first time, they behaved very erratically when adjusting the relative phase. As it turned out, the two coils had an unexpectedly strong ability to wirelessly couple power to each other, which wreaked havoc with the way we were controlling them. This headache eventually turned into a bit of fun though, since we were able to optimize their wireless capabilities enough to actually power a small manned vehicle, shown here: http://www.youtube.com/watch?v=CULdwXKKfDQ I can only guess at some of the anomalies we'll run into when trying to ramp up the Lightning Foundry, but I'm certain the process will not be anomaly-free. -Greg Leyh
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. I'm proposing that it’s now arguably practical to build a machine large enough to recreate the conditions that theory predicts will trigger a relativistic runaway breakdown in air, on demand, and in a well-instrumented environment. More info on the project can be viewed here: http://www.lod.org/Projects/LightningFoundry/LightningFoundry.html Let me know if you'd like any more info. -Greg Leyh
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.
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 generate what is called a ‘superlong discharge’, which is shown in your link. I haven’t come across a solid explanation for superlong discharges, nor do I know if they’re related to relativistic breakdown effects. However the SIBNIIE Marx did generate more than enough voltage to produce relativistic electrons. I do think there's some very interesting physics going on there that's worth pursuing.
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
The expected formation time of a relativistic breakdown is also on the order of 10s of microseconds. Compare this to the 20% flat-top duration of the Lightning Foundry output voltage sine wave, which at 5200Hz is about 40 microseconds. Although not a perfect DC source, hopefully the 40usec 20% flat-top will be able to generate significant RRB precursors. If we do start to see precursors we’ll likely add capacitance to lower the frequency, which will extend the flat-top duration.
I'd like to offer the 'Vomit Comet' as an analogous example. Even though gravity is a 'DC' effect, the sine-wave trajectory of the Vomit Comet can induce a zero-gravity environment for a suitably long time during the crest of the trajectory. For some, it's too long.
If we do come across strong precursors or other compelling results at our lowest possible frequency then the next step might be to increase the coil size, or propose building a considerably more expensive DC machine.
The Lightning Foundry will be orders of magnitude more cost effective than a DC machine at this voltage level, and be able to operate at a much higher repetition rate. In addition, there’s other interesting research that an AC machine like the Lightning Foundry can carry out such as explorations in wireless power, or some unique coupling experiments with the Schumann Cavity.
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 watching the picture quality.
Of greater concern is the potential acoustic noise. The Lightning Foundry arcs could easily produce over 100kilowatts of acoustic power. To deal with this and general safety concerns we plan to operate the Lightning Foundry in a remote, mountainous section of southern Nevada, about 10mi from Boulder Dam.
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.
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 captured:
http://www.lod.org/Projects/electrum/techdata/waveforms.htm
Note the appearance of unexpected high frequency bursts that appear on the crests of the wave in the last two images. They have about a 400nsec time constant. They occur only on the *negative* crest, in a time frame where the output voltage is essentially DC. I still don’t have a good explanation for these odd bursts.
With the Lightning Foundry, we’ll be looking instead for relativistic runaway breakdown events in air. Specifically we’ll use wide spectrum radio receivers to look for narrow bipolar pulses, and gamma-ray detectors to survey for evidence of relativistic particles.
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
Slashdot Mirror
Hi, hopefully my response in 'Re:AC_DC' above will answer your question. -Greg Leyh
I don't think that I could do that.
Hello, here's the project overview on our website: http://www.lod.org/Projects/LightningFoundry/LightningFoundry.html I couldn't find the word 'cool' listed there but the word 'goal' occurs several times.
Hopefully my response in 'Re:AC_DC' below will answer your question. -Greg Leyh
The 'voltage economy' mentioned above occurs during the stepped leader phase, which is very low current compared to the return stroke. High current arc discharges at the laboratory scale fair no differently than low current ones; the current only occurs after the initial breakdown phase, so it cannot be a factor. Seriously, if you think you have a valid answer for this, you should publish.
Each tower will require up to 1.8 megawatts of AC prime power. The most economical AC power choice would be the local power grid. However, if the Lightning Foundry is required to operate in a remote area or if the local power authority cannot handle megawatt transient loading, then there are two options for generating the AC prime power: A) An gas turbine-alternator set or B) A stand-alone diesel generator. Option A is preferred over B, since a turbine set is considerably more compact and is easier to transport. If we’re not able to score an affordable turbine set or secure a robust connection to the power grid, then leasing a 2MW Diesel generator set is the remaining option.
Hi Ralf, That interview was interesting [got to visit the amazing Google campus] but unfortunately it was completely unrelated to the Lightning Foundry. It involved something considerably more practical than pure research. I'm pretty sure there wasn't a video.
Hi, take a look at my response in 'Re:AC_DC' above, and let me know if that answers your question. -Greg Leyh
Certainly, most people will find this boring. Especially with all of the amazing diversions and entertainment available today.
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 The Lightning Foundry should be able to explore a portion of the parameter space in Figure 2, and a good part of the 'Semi-stable' regime in Figure 3.
Unfortunately I doubt the Lightning Foundry would be able to approach the magnificence of the Sousaphone.
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 small percentage of these become discoveries. When we brought up the 1:12 scale Lightning Foundry prototypes for the first time, they behaved very erratically when adjusting the relative phase. As it turned out, the two coils had an unexpectedly strong ability to wirelessly couple power to each other, which wreaked havoc with the way we were controlling them. This headache eventually turned into a bit of fun though, since we were able to optimize their wireless capabilities enough to actually power a small manned vehicle, shown here: http://www.youtube.com/watch?v=CULdwXKKfDQ I can only guess at some of the anomalies we'll run into when trying to ramp up the Lightning Foundry, but I'm certain the process will not be anomaly-free. -Greg Leyh
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.
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. I'm proposing that it’s now arguably practical to build a machine large enough to recreate the conditions that theory predicts will trigger a relativistic runaway breakdown in air, on demand, and in a well-instrumented environment. More info on the project can be viewed here: http://www.lod.org/Projects/LightningFoundry/LightningFoundry.html Let me know if you'd like any more info. -Greg Leyh
Tesla, definitely. He’ll know a great place for dinner and tell better stories.
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.
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 generate what is called a ‘superlong discharge’, which is shown in your link. I haven’t come across a solid explanation for superlong discharges, nor do I know if they’re related to relativistic breakdown effects. However the SIBNIIE Marx did generate more than enough voltage to produce relativistic electrons. I do think there's some very interesting physics going on there that's worth pursuing.
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 The expected formation time of a relativistic breakdown is also on the order of 10s of microseconds. Compare this to the 20% flat-top duration of the Lightning Foundry output voltage sine wave, which at 5200Hz is about 40 microseconds. Although not a perfect DC source, hopefully the 40usec 20% flat-top will be able to generate significant RRB precursors. If we do start to see precursors we’ll likely add capacitance to lower the frequency, which will extend the flat-top duration. I'd like to offer the 'Vomit Comet' as an analogous example. Even though gravity is a 'DC' effect, the sine-wave trajectory of the Vomit Comet can induce a zero-gravity environment for a suitably long time during the crest of the trajectory. For some, it's too long. If we do come across strong precursors or other compelling results at our lowest possible frequency then the next step might be to increase the coil size, or propose building a considerably more expensive DC machine. The Lightning Foundry will be orders of magnitude more cost effective than a DC machine at this voltage level, and be able to operate at a much higher repetition rate. In addition, there’s other interesting research that an AC machine like the Lightning Foundry can carry out such as explorations in wireless power, or some unique coupling experiments with the Schumann Cavity.
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 watching the picture quality. Of greater concern is the potential acoustic noise. The Lightning Foundry arcs could easily produce over 100kilowatts of acoustic power. To deal with this and general safety concerns we plan to operate the Lightning Foundry in a remote, mountainous section of southern Nevada, about 10mi from Boulder Dam.
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.
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 captured: http://www.lod.org/Projects/electrum/techdata/waveforms.htm Note the appearance of unexpected high frequency bursts that appear on the crests of the wave in the last two images. They have about a 400nsec time constant. They occur only on the *negative* crest, in a time frame where the output voltage is essentially DC. I still don’t have a good explanation for these odd bursts. With the Lightning Foundry, we’ll be looking instead for relativistic runaway breakdown events in air. Specifically we’ll use wide spectrum radio receivers to look for narrow bipolar pulses, and gamma-ray detectors to survey for evidence of relativistic particles.
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