--- Paul <[EMAIL PROTECTED]> wrote: > --- Robin van Spaandonk <[EMAIL PROTECTED]> > wrote: > > In reply to Paul's message of Wed, 11 Oct 2006 > > 08:11:08 -0700 > > (PDT): > > Hi Paul, > > [snip] > > >contact with his daughter. BTW, do you have a > > contact > > >for five nines grade iron? > > [snip] > > Isn't pure iron just going to convert all those > > lovely microwaves > > into pure heat? > > Regards, > > > > Robin van Spaandonk > > > Hi Robin, > > Under normal usage the magnetic material absorbs > most > of the radiation. The radiation is typically in the > hundreds of MHz (not GHz) for non-electrical > materials > and considerably lower in frequency for electrically > conductive materials such as iron. In electrically > conductive materials the free electrons act as > inductance, which slows down the electrons flip > rate. > So in iron, depending on purity, the peak radiation > frequency ranges from KHz to MHz, not hundreds of > MHz > let alone GHz. Even if it were microwaves (GHz), > which > for the most part the radiation is not, the metal > would act as a high refractive index. In other > words, > the metal would slow down the radiation velocity. > Furthermore, most of the radiation would internally > reflect off the cores outer walls. Note that in > microwave ovens the metal reflects the radiation-- > only a small amount is absorbed. This process of > slowing down the radiation and reflecting is > understood when studying electrodynamics in detail. > Also you can see this effect in electrodynamic > computer simulations. The end result would be most > of > the radiation reflecting internally, which would > cause > heat. Here's a list of methods to decrease the > magnetic materials ability to absorb the radiation > in > addition to increasing the potential radiation. > > 1. Use materials with smallest domains at operating > temperatures-- amorphous and nanocrystalline cores. > The smaller the domain the more potential energy. > When > times permit I would like to precisely demonstrate > this in a step-by-step process using conventional > physics. > 2. The thinner the core the better! Your goal is to > prevent the core from absorbing the MCE radiation. > Presently I am pondering upon a design that uses > long > thin magnetic electrically conductive wires. The > thin > wire would be the core and coil. > 3. High saturation materials. A fully saturated core > prevents the intrinsic electron spins from absorbing > the magnetocaloric energy. Of course a fully > saturated > core is useless, but no realistic coil can fully > saturate magnetic material. The core should be close > to saturation. > 4. Unless you use filters you'll need to flip the > process so you can collect the energy during the > cores > radiating cycle. You do this with a permanent > magnet. > Also the PM helps saturate the core, but you don't > want to fully saturate it. > 5. The field from your coil will oppose the PM's > field. So you slowly increase your coil current to > decrease the cores net applied field and then you > want > to drop the current or reverse the current as > quickly > as possible (high di/dt). High di/dt causes a higher > percentage of the electron spins to flip > simultaneously, which in turn greatly reduces the > cores ability to absorb MCE energy, which allows > more > of the energy to escape the core. In short, ultra > high > di/dt lowers the effective permeability, which in > turn > prevents the core from absorbing a great deal of the > MCE energy, which your circuit can then properly > absorb. If the core material has low electrical > resistivity then the Eddy currents will absorb the > radiating energy and then with precise timing you > can > rob a certain percentage of the Eddy currents > energy. >
Robin, I should add there are two methods of extracting MCE energy. If the material is electrically conductive as iron then it is probably best to allow the free electrons to absorb MCE energy in the form of eddy currents. At the precise moment the coil would extract as much eddy current energy as possible. Regards, Paul Lowrance __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com
