Re: The Next Coil
From: Bert Hickman[SMTP:bert.hickman-at-aquila-dot-com]
Reply To: bert.hickman-at-aquila-dot-com
Sent: Tuesday, July 29, 1997 9:01 PM
To: Tesla List
Subject: Re: The Next Coil
Tesla List wrote:
> From: Greg Leyh[SMTP:lod-at-pacbell-dot-net]
> Sent: Monday, July 28, 1997 3:25 PM
> To: Tesla List
> Subject: The Next Coil
> An opportunity has finally arisen to build a new coil from scratch,
> and hopefully benefit from all of the mistakes and discoveries made
> since my last coil design attempt, in 1990. Seven years is long enough!
> Based on countless bits of information exchanged with people on the List,
> numerous PSPICE simulations, and many past mistakes, here are some values
> from the preliminary design set for the new coil:
> Top Capacitance - 130pF (96" OD space frame sphere, 28' altitude)
> The top C is where this coil design starts. I have finally bought into
> the 'huge top C' argument, after reading more about the microsecond
> structures present in lightning as the spark front advances. Even though
> the top C reduces the Vout directly, it appears that a local low-Z
> reservoir of charge must be present at the base of the streamer channel
> in order to solidly support the streamer growth on microsecond timescales.
> Adding a physical 100pF capacitor to my existing coil proved this out.
> -- Preliminary Design Values --
> Lsec = 120mH (37" X 154", 5 turns/inch)
> Fsec = 51kHz (no sphere) 36kHz (w/sphere)
> Cpri = 0.270uF (0.045 X 6 units)
> Vpri = 44kV
> Coupling = 0.22
> Max Break Rate = 400 BPS
> HVPS Capacity = 120kW (3PH to DC, resonant charger)
> Preliminary construction and testing of components is ready to begin, at
> a site inside the Hunter's Point Naval Shipyard, in San Francisco. This
> location was selected for its abundance of cranes and electrical power,
> its high level of security, and its remoteness from residential areas.
> I will post results and pictures as they become available.
Best of luck on the new coil! And I thought your current coil was
awesome...! I must have missed your experiments with adding 100pf of
lumped C to increase streamer propagation - could you describe them a
bit more? And what did you used for a capacitor??
-- Bert H --