\begin{table}%t2
\par
\caption {\label{tab2}The real spatial and time scales
as a function of the chosen plasma density~$n_{\rm e}$.}
%\centering
\par
\begin{tabular}{ccccc}
\hline\hline
$n_{\rm e}$ & $\omega_{\rm pe}$ & $t = 200/\omega_{\rm pe}$  & $\lambda_{\rm D}$ & 1/$\nu_0$ \\
(cm$^{-3}$) & (s$^{-1}$) & (s) & (cm) & (s) \\
\hline
10$^8$ & 5.64 $\times$ 10$^8$ & 3.55 $\times$ 10$^{-7}$ & 3.19 & 3.61 \\
10$^9$ & 1.78 $\times$ 10$^{9}$ & 1.12 $\times$ 10$^{-7}$ & 1.01 & 0.36 \\
10$^{10}$ & 5.64 $\times$ 10$^{9}$ & 3.55 $\times$ 10$^{-8}$ & 0.32 & 0.03 \\
10$^{11}$ & 1.78 $\times$ 10$^{10}$ & 1.12 $\times$ 10$^{-8}$ & 0.10 & 0.003 \\
\hline
\end{tabular}
\end{table}