William Beaty wrote:
On Wed, 12 Nov 2008, Frosty wrote:> I remember reading once that it is thought that natural lightning can > achieve such huge 'spark lengths' at relativley low voltages because of > avalanche break down from (ionizing) cosmic rays.Here's the review article about this, from Physics Today magazine: Runaway Breakdown and the Mysteries of Lightning 2005 Gurevich & Zybin http://www.phy.olemiss.edu/~jgladden/phys510/spring06/Gurevich.pdf Note what's discussed: sparks which are "seeded" with relativistic electrons will travel 10^2- 10^4 times farther than ordinary sparks at the same values of potential. Just imagine: a TC which normally puts out 1-meter sparks might start creating 10-meter sparks. Or 100 meters. (Or 10KM?!!!)
It's important to note that injecting relativistic electrons alone will not produce a relativistic avalanche. In his calculations, Gurevich defines a 'characteristic distance' that the avalanche requires in order to fully develop. He estimates this characteristic distance to be around 60 to 80 meters, in air. An electric field of about 150kV/m to 200kV/m is required along this entire distance.
This 60 to 80m requirement would likely explain why such effects have never been observed in existing test laboratories. However, one wonders if RRB was in part responsible for some of the anomalous strikes that the Russians observed at SIBNIIE in the 60's:
http://www.lightninglab.org/misc/SIBNIIE5MV.jpgIn 2005, after considering the calculations of Gurevich and others a major design option was added to the NLL, allowing the open-air strike distance to be increased up to 80 meters from the previous 65 meters. Admittedly an incremental increase, but statistically significant. I strongly believe there's a good chance the NLL will be able to generate at least gamma-rich precursors, if not a full RRB event.
Tesla's Wardenclyffe, if set up with an high energy X-ray source in the topload, might have also had a good chance at producing RRB precursors. Undoubtedly Tesla would have eventually tried such a thing to test his 'Death Ray' concept.
It would have been interesting if he had finished construction on schedule, and produced RRB precursors about a year before Einstein published General Relativity in 1905.
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