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Re: Tool Steel's
Original poster: Bert Hickman <bert.hickman@xxxxxxxxxx>
Tesla list wrote:
Original poster: Ed Phillips <evp@xxxxxxxxxxx>
Hey Glen...
"oxidation" is going to occur on any type of metal used in a spark
gap... the reason we use copper is for the cooling properties and
electrical conductivity. Other metals cool alot slower than copper
and eventually will become hot enough to maintain an arc alot longer
then copper. The voltages used in a sparkgap are high enough to
destroy almost anything conductive ( not too sure about diamonds
tho) save the money and use the copper :)
Scot D"
Many of the spark gaps used in "wireless telegraphy" had
electrodes made of zinc. Don't know its relative merits but copper
was probably no more expensive so "there must have been a reason" - maybe.
Ed
Hi,
Per Zenneck's excellent book ("Wireless Telegraphy", page 16), a
spark gap between zinc electrodes had a lower equivalent "gap
resistance" than an identical gap between copper electrodes in a
simple LC circuit. Zinc (and magnesium!) gaps were therefore
considered to be less lossy.
However, because of the additional metal vapor in the gap, zinc
electrodes likely also resulted in poorer quenching (than gaps made
from copper) when used in coupled LC circuits.
BTW, a scanned copy of Zenneck's 1915 book can be obtained in its
entirety through the Internet Archive'a Million Book project. The
DjVu file is about 52 MB:
http://www.archive.org/details/WirelessTelegraphy
Best regards,
Bert
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