Re: question

[Tesla729-at-cs-dot-com (by way of Terry Fritz <twftesla-at-uswest-dot-net>)]

Francisco,

I believe you are asking why the primary coil needs to be made
of such a heavy guage conductor? Although the high voltage from
the power transformer is of a relatively low current ( usually from
a few mA to several 100 mA for large coils), the capacitive dis-
charges in the primary tank circuit will have momentary currents
of 100s of amps for small coils and 1000s of amps for large coils.
Remember, the transformer charges the capacitor in several 1/1000s
of a second, but the capacitor discharges this same charge into
the primary coil in a few 1/1000000s of a second. This is why a
Tesla coil is often refered to as a "power magnifier", but not an
energy magnifier. Power=Energy/Time Interval. John Couture states
in his "Tesla Coil Construction Guide" that the time intervals for a 
typical Tesla coil system is generally in the 1/10000 range. Even
with a primary circuit that only has 30% energy transfer efficiency,
this would still represent a 3000 fold increase in primary peak power
level. For this reason, the momentary current levels of the primary
capacitor's discharge can literally reach 1000s of times greater than
the input current from the HV transformer. This why you need heavy
conductor between the primary capacitor, spark gap, and the pri-
mary coil, including the primary coil itself. I hope this explains it 
to your understanding.

                                                        David