Impedance RF Measurement Coffee Meeting Minutes

March 7^th, 2008

Coffee discussion with J.B. Jeanneret to explain him our work:

• Litz wires (metallic wires, copper here, isolated from each other by enamel* and distributed more or less randomly, but on average parallel to the beam). The goal here is to avoid the induced Eddy currents, which shield the metal and are at the origin of the skin effect…
   
• J.B. Jeanneret proposes to use a dielectric with Epsilonr = 1, i.e. as vacuum => In this case there is no impedance, but the problem here is that there is no dense material (for collimation) with this Epsilonr! Plastic etc… has an Epsilonr = 2, but then it will melt etc.
   
• Fritz proposes to use the Litz wires, which can be seen as hairs, or a comb => We use hairs and combs because it is for the collimation which shaves the beam! (That qualifies as a sentence of the day…) In fact we have to consider two cases: Litz wire with the hairs parallel to the beam as case 1 and mutually isolated wires orthogonal to the beam as case 2.This case 2 is then considered a “comb”.

* Fritz's comment: There is a potential misunderstanding => One finds very often in the literature the phrase "enamelled wire", which may lead to the conclusion that these days there is still real enamel used. Real Enamel coating had been use to some extend more than 50 years ago but now its hard to find (but I think, I will find it). Normally one does not get from industry wire with real enamel coating anymore and the word is a synonym for some sort of plastic coating.

 

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