From: Paul
Date: Tue, 12 Jun 2001 10:41:23 +0100
Subject: Re: [TSSP] Solenoid losses
Malcolm wrote: > ...I've been away for about three weeks. Welcome back! You must be faced with a mountain of email! > Would it be asking too much if someone would please outline where the > work is at and what needs to be done. Sure, I'll take that as an excuse to put out a quick 'progress report', - to follow. Terry wrote: > Dr. Sullivan is obviously very close to the paper writing and academic > world. He write's a good paper doesn't he? Example of how it should be done! The main problem to us with the SFD method is that it assumes the wire is small compared with the skin depth. Therefore, the best we can hope for is good agreement on Q for very small wire coils, deteriorating on the big low-frequency coils with fat wires. 'Charlie' tells me that next year he will have a graduate student working on the problem of large wire wrt skin depth, to try to extend SFD into this domain. So if by then we have implemented SFD, we may have a platform to offer as a testbed. > I have a big 6 gallon glass "carboy" for those stand alone drinking > water dispensers. It is about 12 inches (30cm) diameter and has > about 25cm of usable winding length on it. Is glass a fairly good low > loss material? The loss factor is not at all relevant to this exercise, providing it is not too bad. It's the relative permittivity that counts. The important thing is to find a former which is either negligibly thin, or has a dielectric constant of around unity. An un-varnished coil wound on such a former would be expected to deliver resonant frequencies in agreement with the model. This has been talked about before - a suggestion by Boris for self-supporting coils, although the context was Q factor rather than Cint. More to follow on Cint, but in the other thread. Cheers, -- Paul Nicholson, Manchester, UK. --
Maintainer Paul Nicholson, paul@abelian.demon.co.uk.