[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

*To*: tesla-at-pupman-dot-com*Subject*: Re: spark gap voltages (Secondary capacitance)*From*: "Tesla list" <tesla-at-pupman-dot-com>*Date*: Fri, 24 May 2002 08:13:32 -0600*Resent-Date*: Fri, 24 May 2002 08:17:31 -0600*Resent-From*: tesla-at-pupman-dot-com*Resent-Message-ID*: <17RVJ.A.QI.2tk78-at-poodle>*Resent-Sender*: tesla-request-at-pupman-dot-com

Original poster: "Dave Larkin by way of Terry Fritz <twftesla-at-qwest-dot-net>" <teslaman15-at-hotmail-dot-com> > > A small DC supply is used to charge the primary cap, until the spark gap > > breaks down. The output spark length under these conditions _is_ >(almost) a > > direct relation of voltage. So if a ground terminal with a large ROC >(to > > try and make the field a bit more uniform) is used and the single shot >spark > > length measured, one can determine the approximate output voltage, using >the > > fact that air breaks down at ~1MV/meter for large gaps. > >The correct figure is 30 kV/cm for parallel planes, or terminals where >the radius of curvature (R) is much larger than the distance between the I am well aware that the textbook breakdown for air is 3MV/meter. 1MV/meter is a crude approximation to account for the fact that the field is seriously non-uniform. The equation you posted below seems a much better way of doing things! Is there another equation which accounts for inequal electrode radii? The really accurate method for the test I describe is not to rely on a calculated voltage, but to hook an EHT power supply up to the (formerly) grounded electrode, and actually measure the voltage taken to break down the gap. However the requirement for a multi hundred kilovolt test supply means that for most people it'd probably be easier to simply build the fiber optic probes! -Dave- >terminals (D). When D>>R the voltage tends to be determinated by R only, >as V=60000/R (R in cm, assuming 2 identical balls). An approximate >expression for the voltage between 2 balls with radius R and distance D >is: >V=30000*R*D/(0.9*(R+D/2)), R and D in cm. >A spark with 20 cm of length between two balls with 2 cm of radius >corresponds to about 111 kV. >Of course, this is for single sparks. > >Antonio Carlos M. de Queiroz > > >

- Prev by Date:
**Re: SRSG timing & other Q's** - Next by Date:
**RE: HV Cable Sources?** - Prev by thread:
**Re: spark gap voltages (Secondary capacitance)** - Next by thread:
**Re: spark gap voltages (Secondary capacitance)** - Index(es):