1 立体角積分

Eq.(31),(32)の立体角積分、

$\displaystyle \frac{dW}{dt}
=
\int_{\Omega}
\frac{d(W_x+W_y+W_z)}{d\Omega dt}
=...
...\frac{\cos^2\theta}{\sin^2\theta}
J_n'^2(\lambda_n)
\right]
\sin\theta d\theta
$

を行う。この角括弧の中は(Bessel Functionの引数$ \lambda_n$は省略する)、

$\displaystyle \left[ \beta^2 J_n^2 + \frac{\cos^2\theta}{\sin^2\theta} J_n'^2 \right]$ $\displaystyle = \beta^2 \left(\frac{J_{n-1}-J_{n+1}}{2}\right)^2 + \frac{1}{\si...
...frac{n^2\beta^2}{\lambda_n^2}J_n^2 -J_n^2 \,; \quad \lambda_n=n\beta \sin\theta$    
  $\displaystyle = \beta^2 \left[ \left(\frac{J_{n-1}-J_{n+1}}{2}\right)^2 + \left...
...)^2 \right] -J_n^2 =\frac{\beta^2}{2} \left( J_{n-1}^2+J_{n+1}^2 \right) -J_n^2$    
  $\displaystyle = \frac{1}{2} \left[ \beta^2 \left( J_{n-1}^2 -2J_n^2 +J_{n+1}^2 \right) \right] -\left(1-\beta^2\right) J_n^2$    

と書ける。これより立体角積分は、

$\displaystyle \int_0^\pi$ $\displaystyle \left[ \beta^2 J_n^2(\lambda_n) + \frac{\cos^2\theta}{\sin^2\thet...
...t_0^{\pi/2} \!\!\!\! + \!\! \int_{\pi/2}^{\pi} \right) \sin\theta J_n^2 d\theta$    

であるが、今

$\displaystyle \int_{\pi/2}^\pi \sin\theta J_n^2(n\beta\sin\theta)d\theta$ $\displaystyle = \int_{\pi/2}^{0} \sin\theta' J_n^2(n\beta\sin\theta')(-d\theta'...
...ccc} \theta & \pi/2 & \to & \pi \\ \hline \theta' & \pi/2 & \to & 0 \end{array}$    
  $\displaystyle = \int_0^{\pi/2} \sin\theta J_n^2(\lambda_n) d\theta$    

であることから、

$\displaystyle \int_0^\pi$ $\displaystyle \left[ \beta^2 J_n^2(\lambda_n) + \frac{\cos^2\theta}{\sin^2\thet...
...ight) d\theta - 2\left(1-\beta^2\right) \int_0^{\pi/2} \sin\theta J_n^2 d\theta$    
  $\displaystyle = \beta^2 \frac{1}{2n\beta} \int_0^{2n\beta} \left( J_{(2n-1)-1}(...
...ght) dt -\frac{2\left(1-\beta^2\right)}{2n\beta} \int_{0}^{2n\beta} J_{2n}(t)dt$    
  $\displaystyle \hspace{80mm} \because\, \int_0^{\pi/2} J_n^2(z\sin\theta)\sin\theta \, d\theta =\frac{1}{2\pi} \int_{0}^{2z} J_{2n}(t)dt$    
  $\displaystyle = \frac{\beta}{n} \int_0^{2n\beta} \left( J_{2n-1}'(t)-J_{2n+1}'(...
...y}{c\vert ccc} t & 0 &\to & 2n\beta \\ \hline \xi & 0 & \to & \beta \end{array}$    
  $\displaystyle = \frac{\beta}{n} \left[ J_{2n-1}(t) -J_{2n+1}(t) \right]_0^{2n\b...
...}{n} J_{2n}'(2n\beta) -2 \frac{1-\beta^2}{\beta} \int_0^\beta J_{2n}(2n\xi)d\xi$    

を得る。以上より立体角積分をした結果は以下のようになる:

$\displaystyle \frac{dW}{dt} = \frac{2e^2\omega_{{\rm se}}}{c\beta} \sum_{n=-\in...
...'(2n\beta) -n^2 \left(1-\beta^2\right) \int_0^\beta J_{2n}(2n\xi)d\xi \right] .$ (55)

著者: 茅根裕司 chinone_at_astr.tohoku.ac.jp