\def\GWslide{
\slide{From measured signals to $\tau_{E,e}$ @tG}{
\scriptsize
\begin{center}
\resizebox{\textwidth}{!}{%
\begin{tikzpicture}[
  node distance=7mm and 11mm,
  block/.style={rectangle,draw,rounded corners,align=center,fill=blue!5,inner sep=3pt,text width=3.0cm},
  bigblock/.style={rectangle,draw,rounded corners,align=center,fill=orange!20,inner sep=3pt,text width=6.5cm},
  line/.style={->,thick}
]
% --- Row 1: input signals
\node[block] (vac) {Vacuum discharge\\$I_{\rm ch}^{\rm vac}(t)$, $V_{\rm loop}^{\rm vac}(t)$};
\node[block,right=of vac] (plasma) {Plasma discharge\\$I_{\rm ch+p}(t)$, $V_{\rm loop}(t)$, $n_e(t)$};
% --- Row 2: R_ch and I_p
\node[block,below=of vac] (Rch) {Chamber resistance\\$R_{\rm ch} \approx \dfrac{V_{\rm loop}^{\rm vac}}{I_{\rm ch}^{\rm vac}}$};
\node[block,below=of plasma] (Ip) {Plasma current\\$I_p = I_{\rm ch+p}-\dfrac{V_{\rm loop}}{R_{\rm ch}}$};
\path[line] (vac) -- (Rch);
\path[line] (plasma) -- (Ip);
% --- Row 3: QS averaging
\node[bigblock,below=of $(Rch)!0.5!(Ip)$] (qs)
{Quasi--stationary interval $[t_1,t_2]$:\\
$\bar I_p=\langle I_p\rangle,\quad
 \bar V_{\rm loop}=\langle V_{\rm loop}\rangle,\quad
 \bar n_e=\langle n_e\rangle$};
\path[line] (Rch) |- (qs);
\path[line] (Ip) |- (qs);
% --- Row 4: R_p, T_e, P_OH
\node[block,below left=of qs] (Rp) {Plasma resistivity\\$R_p=\dfrac{\bar V_{\rm loop}}{\bar I_p}$};
\node[block,below=of qs] (Te) {Central $T_e$ (Spitzer)\\$T_e(0)\approx0.9\,R_p^{-2/3}$};
\node[block,below right=of qs] (Poh) {Ohmic heating\\$\bar P_{\rm OH}=\bar V_{\rm loop}\,\bar I_p$};
\path[line] (qs.south west) |- (Rp);
\path[line] (qs) -- (Te);
\path[line] (qs.south east) |- (Poh);
\path[line] (Rp) -- (Te);
% --- Row 5: W_e
\node[block,below=of Te,fill=blue!10] (We)
{Electron energy\\$\bar W_e=\tfrac{3}{2}\,\bar n_e k_{\rm B} T_e V_p$};
\path[line] (Te) -- (We);
% --- Row 6: tau_Ee (centered)
\node[bigblock,below=of We,fill=green!20] (tau)
{Electron energy confinement time\\$\displaystyle \tau_{E,e}=\dfrac{\bar W_e}{\bar P_{\rm OH}}$};
\path[line] (We) -- (tau);
\path[line] (Poh.south) |- (tau.east);
\end{tikzpicture}%
}
\end{center}
}}