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idea on Jm and the homo solutions v2 REVIEWED
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A short working note by Phil dated 1.15.14, with a closing time stamp of 1.16.14, from his transmission-line Appendix B material. It conjectures that the Jm integral supplies the homogeneous solutions that make the Az boundary conditions match at a conductor surface. It uses a 2D propagator, a surface current Kz tied to Hθ, and Stakgold's single-layer normal-derivative jump relation. The algebra ends in 0 = 0, and Phil asks whether the argument is circular.
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Crazy idea on Jm and the homo solutions PhL 1.15.14
Again, this general idea is now installed as Section B.6 (b)
Conjectured Theorem: If you add Jm to your Jc, the extra Jm integral gives exactly the right homo solutions to make the Az boundary conditions match.
Attempted Proof: Start with Appendix C.4's starting point
Az(x) = ∫ dV' [μ2Jcz(x') + μ0Jmz (x')] R = |x - x'| ω = 0 (1.5.9)
= Az(c) + Az(m)
I will show later that one can add an arbitrary surface current and that only changes the homo solutions, and I choose the current shown above.
1. I know that the "conduction current term" has this property at the boundary between μ1 and μ2:
[Az(c)]1 = [Az(c)]2 1 = dielectric = outside wire
[∂n Az(c)]1 = [∂n Az(c)]2
Therefore I know that
[∂n Az(c)]1 – [∂n Az(c)]2 = [-][∂n Az(c)]
This is the quantity that we want the Jm term to cancel out.
2. The "magnetization current term" is this
Az(m) = μ0 ∫ dV' Jmz (x')]
where Jmz (x') is confined to the conductor surface and this has the usual (-∞,∞) dz' integral. The mag current density is in the form of a 3D density of amps/m2.
However, with the usual set of assumptions I can replace this 3D integral and propagator with as 2D integral and propagator as follows:
Az(m) = μ0 ∫ dA' Jmz (x')] [ - ln(R) ]
Now since we know that Jmz (x') is confined to the 2D perimeter in this 2D picture, we then write
Az(m) = μ0 ∫C ds' Kmz (x')] [ - ln(R) ]
where we have now "taken out the delta function" so K is amps/m. I showed in Appendix B that
Kz = - ( - ) Hθ where Hθ > 0 and Kz ≤ 0.
so we then have
Az(m) = - (μ2-μ1) ∫C ds' Hθ(x')] [ - ln(R) ]
= ∫C ds' [(μ1-μ2) Hθ(x')] [ - ln(R) ]
= ∫C ds' a(x')] E(x|x') . a(x') = (μ1-μ2) Hθ(x')
3. Now recall from Stakgold these facts
u(x) = ∫σ dSξ a(ξ) E(x|ξ)
u(s) = ∫σ dSξ a(ξ) E(s|ξ)
∂νu(x) = ∫σ dSξ a(ξ) ∂νE(x|ξ) ∂ν = normal to surface σ = I write as ∂n
∂νu(s) = [∂νu(x)]x=s+ = ∫σ dSξ a(ξ) ∂νE(x|ξ) - a(s)/2 // the extra term!
where σ is a surface of interest. We take now this surface to be our perimeter and then E is the 2D E. Thus we expect to find that
[∂nAz(m)(x)]1 = ∫C ds' [(μ1-μ2) Hθ(x')] ∂nE(x|x') - [(μ1-μ2) Hθ(x)]/2 (**)
[∂nAz(m)(x)]2 = ∫C ds' [(μ1-μ2) Hθ(x')] ∂nE(x|x') + [(μ1-μ2) Hθ(x)]/2
Now compute our "correction term" for the difference boundary condition,
[∂nAz(m)(x)]1 – [∂nAz(m)(x)]2
= {∫C ds' [(μ1-μ2) Hθ(x')] ∂nE(x|x') [- ] - [(μ1-μ2) Hθ(x)] [+ ]/2
= (μ1-μ2) [- ] ∫C ds' Hθ(x')] ∂nE(x|x') - (1/2) (μ1-μ2) [+ ] Hθ(x)
This then is our candidate correction term which we want to cancel the original term. I am not sure how that is going to happen! The original was this:
[∂n Az(c)]1 – [∂n Az(c)]2 = [- ][∂n Az(c)]
Thus this is what I WANT to be true (add above two equations and hope for 0)
(μ1-μ2) [- ] ∫C ds' Hθ(x')] ∂nE(x|x') - (1/2) (μ1-μ2) [+ ] Hθ(x) + [- ][∂nAz(c)]= 0
The μ factors don't look right, but let's plough ahead . Write
[- ] = (μ2- μ1)/(μ1μ2) = - (μ1-μ2) /(μ1μ2)
on the far right only, then cancel one factor (μ1-μ2) to get
[- ] ∫C ds' Hθ(x')] ∂nE(x|x') - (1/2) [+ ] Hθ(x) - [∂n Az(c)] = 0
Further simplify to
(μ2- μ1) ∫C ds' Hθ(x')] ∂nE(x|x') - (1/2) (μ2+μ1) Hθ(x) - [∂n Az(c)] = 0 (*) ??
I have obtained the above equation in my Section B.6 writeup.
Once again, I am trying to show that (*) is true, I have not shown it is true! I do know from (**) that
∫C ds' [(μ1-μ2) Hθ(x')] ∂nE(x|x') = [∂nAz(m)(x)]1 + [(μ1-μ2) Hθ(x)]/2 agree
so then here is what I want to show is true:
-[∂nAz(m)(x)]1 - [(μ1-μ2) Hθ(x)]/2 - (1/2) (μ2+μ1) Hθ(x) - [∂n Az(c)] = 0 ??
or
[∂nAz(m)(x)]1 + [(μ1-μ2) Hθ(x)]/2 + (1/2) (μ2+μ1) Hθ(x) + [∂n Az(c)] = 0 ??
or
[∂nAz(m)(x)]1 + μ1 Hθ(x) + [∂n Az(c)] = 0 ??
Now how is Hθ related to Az ? If we define a little local cylindrical coordinate system, then we know that
B = curl A = [ r-1∂θAz - ∂zAθ] + [∂zAr - ∂rAz] + [ r-1∂r(rAθ) - r-1∂θAr
= [ r-1∂θAz] + [- ∂rAz]
For a circular boundary this would be just B = [- ∂rAz] since Az is constant on the surface. Let us now conjecture that for a general perimeter we have
B = [- ∂nAz ]
where is a local tangent vector as I often use. Then we could claim that
Bθ = - ∂nAz .
What Az is this? It should be the "true one" where BC's are met, so this says
Bθ = - ∂nAz(c) - ∂nAz(m)
But is this inside or outside? I guess we have to say
Bθ1 = - [∂nAz]1
Bθ2 = - [∂nAz]2
Then we can write
H(θ) = Bθ1/μ1 = Bθ2/μ2 take your choice
So I choose 1 and outside to get
H(θ) = Bθ1/μ1 = -(1/μ1) [∂nAz(c) + [∂nAz(m)]1]
or
μ1 H(θ) = Bθ1 = - [∂nAz(c) + [∂nAz(m)]1]
Now try this in our ?? equation:
[∂nAz(m)(x)]1 + μ1 Hθ(x) + [∂n Az(c)] = 0 ??
[∂nAz(m)(x)]1 - [∂nAz(c) + [∂nAz(m)]1] + [∂n Az(c)] = 0 ??
0 = 0 !!!!!
Did I just go in a circle, or have I really succeeded here? Time is 8:13 AM 1.16.14.