\def\path{Education/ExperimentMenu/DataEvaluation/figs}
\def\DataEvaluation{
This section starts with a short description on how to reconstruct the measured plasma parameters from the raw signals returned by GOLEM\_get\_data.m. Measurement tasks are detailed in the later subsections.

The sampling rate of the time resolved measurements (samplerate), time delay between starting diagnostics and toroidal magnetic field drive (trigger) and time delay between toroidal field and inductive current drive (time\_delay) are returned by GOLEM\_get\_data.m, and these are to be used whenever needed instead of the examples providde in this description.

The simplest signal to be reconstructed is the loop voltage ($U_l$). The measurement loop of the loop voltage is connected to a voltage divider, therefore the signal must be multiplied by a calibration factor (U\_loop\_calibration) as plotted in Figure \ref{fig:bd_U_l}.

\begin{figure}[ht]
\centerline{\resizebox{100mm}{!}{\rotatebox{0}{\GWincludegraphics{trim=0cm 8.5cm 9cm 4cm, clip=true}{\path/bd_U_l.pdf}}}}
	\caption{Block diagram showing the steps of data processing for loop voltage measurement.}
	\label{fig:bd_U_l}
\end{figure}

The toroidal magnetic field ($B_t$) and the total current ($I_{tot}$) raw signals must be integrated before multiplying by calibration factors (Bt\_calibration and Rogowski\_calibration). The reason for this is that the voltage measured is induced in these diagnostic loops and coils by the changing of the toroidal and poloidal magnetic field respectively.

Integrated magnetic measurements are very sensitive to the DC bias of the measurement circuit, which needs to be corrected for. If the sampling rate is 1 MHz, and the shot starts at 5 ms, we have 5000 samples from the background noise. It is better to exclude a few samples around the swithing time point. This is important, because these samples measure the bias, and we can correct the integrated values with this factor.

Figure \ref{fig:bd_dB_t} shows the block diagram for the necessary steps of processing of the toroidal magnetic field signal. Routines for all the steps are ready, they should just be parametrized and linked.

\begin{figure}[ht]
\centerline{\resizebox{160mm}{!}{\rotatebox{0}{\GWincludegraphics{trim=1cm 8.5cm 0cm 4cm, clip=true}{\path/bd_dB_t.pdf}}}}
	\caption{Block diagram showing the steps of data processing for toroidal magnetic field measurement.}
	\label{fig:bd_dB_t}
\end{figure}

The block diagram for the total current measured by the Rogowski coils is only slightly more complicated: Switching the toroidal magnetic field on causes an offset in the toroidal current measurement, which has to be corrected by subtracting the average value measured in the $\tau_{OH}$ long interval before switching on the toroidal electrical field from the integrated current value.

\begin{figure}[ht]
\centerline{\resizebox{160mm}{!}{\rotatebox{0}{\GWincludegraphics{trim=1cm 5cm 0cm 4cm, clip=true}{\path/bd_dI_t.pdf}}}}
	\caption{Block diagram showing the steps of data processing for total plasma current measurement.}
	\label{fig:bd_dI_t}
\end{figure}
}