RF envelope waveshape: the answer to short SSTC sparklength?

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Original poster: "Justin Hays by way of Terry Fritz <twftesla-at-qwest-dot-net>" <pyrotrons2000-at-yahoo-dot-com>

Hi All.

Our results:

With 1/2 wave rectified DC input to an SSTC half OR full bridge (same
results with both circuits), arcs are a certain length. The circuit
dissipates a given amount of power.

With full wave rectified DC input, the arcs are thicker, but only a
little longer. It eats around TWICE the average power.

With a big filter capacitor across the input, arclength decreases
drastically, and input power increases to some very high value.

What does it mean? Shouldn't more power mean longer sparks? Many
solid-state coilers blame the shape of the RF envelope...which sounds
good to me, since that's about the only other readily-noticeable
variable. So if it is, wouldn't the next question be, what envelope
shape produces the longest sparks? 

We've found little pulses (short duty cycle) of RF to be the most
efficient as far as sparklength goes. With short pulses applied to
the primary coil, the output arcs look VERY similar to that of a
disruptive spark-gap type coil, and they are quite a bit longer than
a "rounded off" looking pulse ---- such as with simple half-wave
rectification into a SSTC half or full-bridge MOSFET circuit.

Of course the current in the discharge goes down significantly with
short pulses vs. long "rounded off" pulses. But average input power
goes down also.....this seems to be a very understandable
relationship. Thinner sparks, less input power. But why the same
sparklength (output voltage)?

Our conclusion: 

Somewhere between driving a secondary coil with a small pulse, and
driving it with a continuous application of RF, is perhaps, a very
interesting phenomena.

The waveshape of the RF envelope is incredibly important to coil
output voltage and current. Why?

Justin Hays
KC5PNP
Email: justin-at-hvguy-dot-com
Website: www.hvguy-dot-com



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