Answer
$P = 9.4\times 10^5~W$
Work Step by Step
We can find the maximum possible intensity:
$I = \frac{1}{2}~E^2~\epsilon_0~c$
$I = (\frac{1}{2})(3.0\times 10^{6}~V/m)^2 (8.854\times 10^{-12}~F/m)~(3.0\times 10^8~m/s)$
$I = 1.2\times 10^{10}~W/m^2$
We can find the maximum possible power:
$I = \frac{P}{A}$
$I = \frac{P}{\pi~r^2}$
$P = \pi~r^2~I$
$P = (\pi)~(0.0050~m)^2~(1.2\times 10^{10}~W/m^2)$
$P = 9.4\times 10^5~W$
