From: Paul
Date: Wed, 25 Oct 2000 07:14:43 +0100
Subject: Re: [TSSP] NSVPI - Latter Results
I've recomputed the model of Terry's coil having adjusted the E-field loss factor to give the measured Q of 70, and I've altered the inductance to 75.1mH I expected that the raised inductance and the increased loss would dispose of some of the residual few percent error in the top voltage estimate as compared with the integrated value from Terry's gradient measurements. In fact this hasn't happened. Short of tampering with the capacitance distribution produced by the laplace solver I can't get rid of the residual error. The plummeting Q has not noticeably reduced the transimpedance so the predicted topvolts remains on the high side of the measurement. One thing of note is that now the loss factor has been set to match the given Q, the input impedance prediction comes out at 713 ohms - in accordance with Terry's measurements. Previous attempts to make both Q and Zin match simultaneously failed since the extra loss was imposed by artificialy increasing Rs. Attributing all the extra loss to the E-field does the trick nicely, and gives me a bit more confidence in the stored energy and Q factor calculations. Under these conditions, the energy loss breakdown in the secondary is 83% into the E-field, presumably mostly sonotube, and 17% into the coil resistance. The overall E-field loss factor required to drop the Q to 70 is a whopping 0.0139, considering the sonotube takes up a small volume of the field, the sonotube loss itself must be very high indeed. Regards, -- Paul Nicholson, Manchester, UK. --
Maintainer Paul Nicholson, paul@abelian.demon.co.uk.