second Mie scattering attempt1
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Phil's working note, dated 2.15.03, in a junk bin folder. It follows Krugel's setup of plane, scattered and internal fields in M and N vector harmonics, applies boundary conditions at r=a, and solves for coefficients a, b, c, d with Maple. He finds unwanted n^2 factors, so the result is wrong, and an appendix tests a hypothesis of omitting the H-to-H' factors, which also fails.
AI-written summary; may contain errors.
Extracted text (machine-read; may contain errors)
Second Attempt at Mie Scattering Coefficients PhL 2.15.03
Attempt to set up the scattering problem in the N and M world, Version 2
Here is Krugel's setup of the problem:
Ep = E [ M(1)o1 - i N(1)e1 ] E = i // incident plane wave
Es = E [ - b M(3)o1 + i a N(3)e1 ] *** // incident plane wave, (3) means h(1) (kr)
Ei = E [ c M(1)o1 - i d N(1)e1 ] // incident plane wave, (1) means j(kr)
Now we write the H equations using our above 3 rules from going from E to B noted above:
" Summary: To get B from E, for each term use the nature of, and -i times the coeff of, the cross term. "
H'p = H [ - M(1)e1 - i N(1)o1 ] H = i
H's = H [ a M(3)e1 + i b N(3)o1 ]
H'i = H [ - d M(1)e1 - i c N(1)o1 ]
Now use H' = H and = 1/ = v/c and 1/ = = n, the index.
Hp = no H [ - M(1)e1 - i N(1)o1 ] H = i // OK only if = 1
Hs = no H [ a M(3)e1 + i b N(3)o1 ]
Hi = ni H [ - d M(1)e1 - i c N(1)o1 ] / i = inside
Now the boundary conditions are of the general form
Xi = Xp + Xs
evaluated at r=a, because both the plane wave and the scattered wave are on the "outside", while the internal is on the "inside". So we can write our boundary conditions as
r x Ei = r x Ep + r x Es
r x Hi = r x Hp + r x Hs
In each expansion, we can then remove the sum and ignore the constant X overall factor and we end up with
inside plane scattered
r x [ c M(1)o1 - i d N(1)e1 ] = r x [ M(1)o1 - i N(1)e1 ] + r x [ - b M(3)o1 + i a N(3)e1 ]
r x [- ni d M(1)e1 - i ni c N(1)o1 ] = r x [ - no M(1)e1 - no i N(1)o1 ] + r x [ no a M(3)e1 + i no b N(3)o1 ]
Balance the M and N terms separately, and use these results derived elsewhere:
r x M(1)o1 = f * - r2 o
r x N(1)o1 = (rf)' / n * (1/k) r x o // k here on right is /c
Here are the results of this balance,
c ji = 1 jo - b ho
- i d (rji)' /ni = - i (rjo)' /no + i a (rho)' /no
- ni d ji = - no jo + no a ho
- i ni c (rji)' /ni = -i no (rjo)' /no + i no b (rho)' /no
First stage simpify, and use n = ni / no
c ji = jo - b ho
- d (rji)'= - n (rjo)' + n a (rho)'
- nd ji = - jo + a ho
- c (rji)'= - (rjo)' + b (rho)'
Rewrite for Maple:
c* ji = jo - b* ho
- d* rjip = - n*rjop + n*a* rhop
- n*d *ji = - jo + a* ho
- c* rjip = -rjop + b* rhop
Put these into Maple: The result is this:
2
-rjop ho + rhop jo ji rjop - jo rjip n ji rjop - jo rjip n (-rjop ho + rhop jo)
{c = ------------------, b = ------------------, a = ---------------------, d = ----------------------}
-rjip ho + rhop ji -rjip ho + rhop ji 2 2
-rjip ho + n rhop ji -rjip ho + n rhop ji
As usual, this result is wrong, and is even more wrong than last time! The n2 factors are back!
Apepndix: Hypothesis #1 again.
Suppose I now omit the H to H' factors. Tha means to remove explicit n's from last two equations. Go back above and start with
c ji = 1 jo - b ho
- i d (rji)' /ni = - i (rjo)' /no + i a (rho)' /no
- ni d ji = - no jo + no a ho
- i ni c (rji)' /ni = -i no (rjo)' /no + i no b (rho)' /no OK
Now remove those n factors from last 2 equations
c ji = 1 jo - b ho
- i d (rji)' /ni = - i (rjo)' /no + i a (rho)' /no
- d ji = - jo + a ho
- i c (rji)' /ni = -i (rjo)' /no + i b (rho)' /no
And now simplify some more
c ji = jo - b ho
- d (rji)' = - n(rjo)' + a n (rho)'
- d ji = - jo + a ho
- c (rji)' = - n (rjo)' + b n (rho)'
And our new Maple equation set is (first 2 are same)
c* ji = jo - b* ho
- d* rjip = - n*rjop + n*a* rhop
- d *ji = - jo + a* ho
- c* rjip = -n*rjop + n*b* rhop
This gives Maple result,
n (rjop ho - jo rhop) n (rjop ho - jo rhop) n ji rjop - jo rjip n ji rjop - jo rjip
{d = - ---------------------, c = - ---------------------, b = -------------------, a = -------------------}
%1 %1 %1 %1
%1 := -rjip ho + n rhop ji
which of course is still wrong. So this hypothesis does not fix things!