From: "Malcolm Watts"
Date: Sun, 25 Jul 2004 12:38:08 +1200
Subject: Re: [TSSP] Bang energy vs. streamer length measurements
Hi Marco, Thanks for an interesting and infornmative set of measurements. Apologies for not commenting before now (overwhelmed by too many things). I do have a couple of comments to make which may or may not be useful. You wrote: >Several trials have indicated that 20 seconds between two bang >sequences is sufficient to ensure statistical independence. On the >other end, it has been easy to notice measurement correlation for a >delay of 5 - 10 seconds. That fits with a finding I made with one particular coil configuration that increasing the "single-shot" frequency from about 1Hz to 2Hz almost doubled (somewhere around 80% I would say) the distance that a leader connected to a grounded target i.e. the distance was adjusted for each PRF to get something like a 90% hit rate. >Bang repetition can't do miracles if the bang energy is limited. This observation makes it clear that for a classic SG configuration, John Freau's Pwr vs sparklength formula defines a best-you-can-do figure for some given power input. In other words, an increase in power in the form of increased BPS beyond this lowers what one might term the "efficiency" of the coil. It also appears that this ties in with John's observation that bigger bangs at lower BPS will always do better for a given power input, at least up to some minimum BPS. >My personal opinion is that an increased bang frequency interacts >with the accumulated space charge and "strightens" the leader path. I think the observed "sword-like" sparks in interrupted CW operation where many tens of cycles are allowed per break supports this observation. Malcolm
Maintainer Paul Nicholson, paul@abelian.demon.co.uk.