From: Paul
Date: Wed, 18 Oct 2000 11:55:12 +0100
Subject: Re: [TSSP] Surprising secondary voltage profiles
Terrell W. Fritz wrote: I asked: > >How does E-Tesla5 estimate the effect of internal capacitance? > >I think you use a gaussian surface which includes the whole > >coil, so only external flux will be detected. If I 'switch off' > >Cint in tsim, the Fo goes from around 150kHz to around 162kHz. Terry: > It just seems to work out automatically. If I remove the top > terminal, it goes to the bare coil case and you just see the coil's > Medhurst capacitance. I do use different profiles for the bare coil > and coil with a top load cases. In effect, the voltage profiles a > set on the surface of the secondary coil must take this into account > without specifically calculating it. I agree. The fact that E-Tesla5 is giving good answers probably means that by careful or accidental choice of V profiles you have effectively taken into account the Cint. Perhaps this might show up as a breakdown of predictions with extreme H/D ratios, which is probably not a problem. The overall 'magnitude' of Cint is obviously proportional to coil radius, and this proportionality will be observed by the E field solution for the external field too. It would be nice to find a theoretical justification for the chosen V profiles in terms of the energy stored in Cint by the voltage gradient plus the energy stored in Cext by the voltage magnitude, bearing in mind that you are weighting by charge rather than by energy. More pondering required... > My RF power supply is forward power regulated, thus it will have > to dissipate power into an arc or something to really run. > The power dissipation will play havoc with the measurements. Perhaps a dummy load as a pad between generator and coil base? Seems like a lot of power for measurements. I use about 5 watts or so at most, I guess its needed to get a clear reading from the probe. Cheers, -- Paul Nicholson, Manchester, UK. --
Maintainer Paul Nicholson, paul@abelian.demon.co.uk.