All Figures

$\begin{figure} \par\includegraphics[width=8.1cm,clip]{6123fig1.eps} \end{figure}$ Figure 1: Time evolution of the ionisation degree F in a column of the simulation for the first 30 min of the simulation. Upper panel: LTE. Lower panel: TD-NLTE. The TD-NLTE simulation was started with LTE populations. The chromosphere shows large temporal variation in ionisation degree in the LTE case. The ionisation degree in the TD-NLTE case is relatively constant after the first 5 min, when the first few shocks have passed.
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In the text

$\begin{figure} \par\includegraphics[width=17.1cm,clip]{6123fig2.eps} \end{figure}$ Figure 2: Horizontal slices through a simulation snapshot at $t \ensuremath {\!=\!} 60$ min. Columns from left to right: gas temperature, logarithm of the mass density fluctuations $\log (\rho / \langle \rho \rangle)$ , LTE ionisation degree and TD-NLTE ionisation degree F. Top row: $z \ensuremath {\!=\!}0.5$ Mm; middle row: $z \ensuremath {\!=\!} 1$ Mm; bottom row: $z \ensuremath {\!=\!} 1.5$ Mm. The LTE and TD-NLTE ionisation degree panels have the same color scale, which has been clipped at $\log F \ensuremath {\!=\!} -10$ . The black line indicates the position of the vertical cuts of Figs. 3 and 4.
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In the text

$\begin{figure} \par\includegraphics[width=8cm,clip]{6123fig3.eps} \end{figure}$ Figure 3: Vertical cut through the snapshot along the line indicated in Fig. 2. a) gas temperature; b) mass density; LTE c) and TD-NLTE d) ionisation degree; LTE e) and TD-NLTE f) electron density. Note that the deepest layers of the model are not shown.
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In the text

$\begin{figure} \par\includegraphics[width=8cm,clip]{6123fig4.eps} \end{figure}$ Figure 4: Departure coefficients of our model hydrogen atom in the same cut as Fig. 3 for the continuum and level n=5 down to level n=1 from top to bottom. The solution is nearly in LTE from the bottom of the computational domain up to 0.3 Mm above the average Rosseland optical depth unity. The largest deviations occur in cool chromospheric regions in between shocks, where, owing to the low temperature, the Saha-Boltzmann equation predicts a very low occupation fraction for all excited levels.
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In the text

$\begin{figure} \par\includegraphics[width=8.4cm,clip]{6123fig5.eps} \end{figure}$ Figure 5: Histogram of the logarithmic ionisation degree as a function of height for the LTE ( upper panel) and TD-NLTE ( lower panel) case. The averages in LTE and TD-NLTE are plotted as red dashed and blue solid lines, respectively. All columns have been individually scaled to maximum contrast to enhance visibility.
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In the text

$\begin{figure} \par\includegraphics[width=7cm,clip]{6123fig6.eps} \end{figure}$ Figure 6: Average TD-NLTE ionisation degree for our CO⁵BOLD model (solid), CS2002's RADYN model (dashed) and the statistical equilibrium FAL model C (dotted). The zero point of the height scale is the average $\tau_{500} \ensuremath {\!=\!} 1$ height.
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In the text

$\begin{figure} \par\includegraphics[width=8.5cm,clip]{6123fig7.eps} \end{figure}$ Figure 7: Vertical cut through the snapshot along the line indicated in Fig. 2 showing the relative contribution of other elements than hydrogen to the electron density. In the chromosphere the other elements contribute mostly in the high temperature shocks.
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In the text

$\begin{figure} \par\includegraphics[width=8cm,clip]{6123fig3.eps} \end{figure}$	Figure 3: Vertical cut through the snapshot along the line indicated in Fig. 2. a) gas temperature; b) mass density; LTE c) and TD-NLTE d) ionisation degree; LTE e) and TD-NLTE f) electron density. Note that the deepest layers of the model are not shown.
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$\begin{figure} \par\includegraphics[width=8.4cm,clip]{6123fig5.eps} \end{figure}$	Figure 5: Histogram of the logarithmic ionisation degree as a function of height for the LTE ( upper panel) and TD-NLTE ( lower panel) case. The averages in LTE and TD-NLTE are plotted as red dashed and blue solid lines, respectively. All columns have been individually scaled to maximum contrast to enhance visibility.
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$\begin{figure} \par\includegraphics[width=7cm,clip]{6123fig6.eps} \end{figure}$	Figure 6: Average TD-NLTE ionisation degree for our CO⁵BOLD model (solid), CS2002's RADYN model (dashed) and the statistical equilibrium FAL model C (dotted). The zero point of the height scale is the average $\tau_{500} \ensuremath {\!=\!} 1$ height.
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$\begin{figure} \par\includegraphics[width=8.5cm,clip]{6123fig7.eps} \end{figure}$	Figure 7: Vertical cut through the snapshot along the line indicated in Fig. 2 showing the relative contribution of other elements than hydrogen to the electron density. In the chromosphere the other elements contribute mostly in the high temperature shocks.
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