An electric charge distribution produces an electric field  $\overrightarrow{E}=C(1-e^{-\alpha r})\frac{\widehat{r}}{r^2}$ where  $C=\frac{1}{4\pi {\epsilon }_0}$ $\& \alpha$ are constant. If the net charge within the radius  $r=\frac{1}{\alpha }$ is  $(1-e^{-N})$, then find the value of  $\text{'}N\text{'}$?