Gary Lau wrote:
I think I disagree on a couple of points. I don't think that bang *rate* affects the tendency to generate racing sparks, unless changing the rate also affects the bang *size*. Its truly the bang size that matters. In addition to the obvious method of raising the secondary to reduce coupling, I've also found it effective to raise the top load relative to the top of the secondary. This may require the installation of a second, smaller toroid at the top of the secondary, to inhibit corona. I think that increasing the top load size will also reduce the likelihood of generating racing sparks, as the top load voltage will be reduced with higher values of top load capacitance. But one can't simply change the top load size without changing other things as well that will also impact racing sparks, so it's difficult to generalize.
The whole thing of racing sparks is a conundrum anyway. Is it a "breakdown along the secondary" phenomena? Reducing k reduces the voltage, so that attacks the problem at a sort of first principles level. But, is it also a "uneveness of field" that aggravates it: larger toploads tend to create a more even field along the secondary, and so might "raising the secondary" or "removing inner turns of primary".. it might be that the k decrease is incidental, but what's really happening is that the field along the secondary is becoming more uniform.
Is there a fine scale (nanoseconds) timing issue? As current flows into the topload, the voltage rises, but the rate at which it rises is determined by the resonant frequency, and also the relative size of the topload to the self C of the secondary itself. Breakdown is known to be somewhat sensitive to rise time.
Is there a mechanism of charge distribution along the (insulated) surface of the secondary? Has anyone ever made a "ridged" secondary (like HV insulators) to increase the creepage length vs air gap length?
_______________________________________________ Tesla mailing list Tesla@xxxxxxxxxx http://www.pupman.com/mailman/listinfo/tesla