[AMPS] arcs

[Peter Chadwick]

Rich says

>I am not certain, although I have a suspicion that arcing ability
>increases with frequency. .......  I have seen some incredulous arcs in
>my 432MHz 4cx250R amplifier.  I have seen some incredulous tune-C arcs
in
>my SB-220 at 110MHz.

Rich, do you think it possible that the increase in voltage at LF is due
to the fact that at low frequencies, the arc gets the chance to
extinguish during the zero crossing, while at HF, the plasma takes so
long to disperse (in terms of the period of 1 cycle) that it stays a
conductor? So that doesn't explain why the arc initially starts at a
lower voltage when RF is present - although the discharge current
density at a  point
will be greater for a given voltage just because the capcitive reactance
is lower.

Mind you, I've had some pretty incredulous arcs at about 50volts and 5
amps of DC as well, but I feel that Rich is right in his suspicion. The
arcs you can get with DC leads me to wonder why the power bus for modern
US military aircraft is 270volts dc, needing vacuum contactors to
control it. In my innocence, I'd have thought a 400Hz generator and AC
system would be lighter.

73

Peter G3RZP

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