# Experimental Simulation of Lightning Current Discharge on Rocks
## 3 Results
### Arc Discharge Experiment Results  
A photo camera provided approximately the instant (static) tridimensional spatial image of the spark discharge on the target material (Figure 6). Strikes were verified by macroscopically observing the surface of the samples after each lightning strike and labeling the arc entrance and exit location on the surface of samples.  
\begin{table}
\begin{tabular}{c c c} \hline
**Weight \%** & **Samples A1–A4** & **Samples B1–B2** \\ \hline Quartz & 10.2(3) & 54.6(2) \\ Plagioclase & 49.6(4) & 15.7(4) \\ K-feldspar & & 21.0(2) \\ Pyroxene & 18.5(4) & \\ Biotite & 5.6(2) & 7.5(2) \\ Chlorite & & 1.2(4) \\ Actinolite & 6.3(5) & \\ Magnetite & 3.6(2) & \\ Amorphous & 6.2(4) & \\ \hline \end{tabular}
\end{table}
Table 1: Mean mineralogical composition of the bulk rock samples. Standard deviation in parenthesis.  
Figure 5: X-ray diffraction pattern of the samples B1–B2. Qtz = quartz; Plg = plagioclase; Ksp = K-feldspar; Bio = biotite. Observed spectra (red line), fitted spectra (blue solid line), difference plot (below spectra), and Bragg peak positions (tick marks above difference plot) are shown. The weighted R-factor, Rwp, was calculated using the observed and calculated intensities in the powder diffraction patterns.  
Table 2 describes the specimens and the experimental electrical data obtained after each arc flash event. RMS voltage and current data, fault durations, peak and average power, and total energy dissipation data was recorded and calculated as described in the Materials and Methods section.  
\begin{table}
\begin{tabular}{l c c c c c c c} \hline
**Specimen** & **Strike Number** & \(T_{F}\) **(ms)** & \(V_{R}\) **(kV)** & \(I_{R}\) **(A)** & \(P\) **(kW)** & \(\hat{p}\) **(kW)** & \(E\) **(kJ)** \\ \hline Average A0 dry & & 96.86 & 85.26 & 0.53 & 42.25 & 116.28 & 4.09 \\ Sample A1 dry & 1 & 95.97 & 85.13 & 0.52 & 42.07 & 124.65 & 4.04 \\ Sample A2 dry & 1 & 103.74 & 82.82 & 0.51 & 39.72 & 107.28 & 4.12 \\  & 2 & 88.04 & 83.01 & 0.52 & 40.18 & 102.62 & 3.54 \\  & 3 & 96.26 & 85.57 & 0.53 & 42.25 & 129.27 & 4.07 \\  & 4 & 88.61 & 85.65 & 0.53 & 42.52 & 121.36 & 3.77 \\  & 5 & 96.03 & 84.93 & 0.52 & 41.67 & 123.31 & 4.00 \\  & 6 & 103.78 & 79.68 & 0.50 & 36.78 & 117.00 & 3.82 \\ Average A2 & & 96.08 & 83.61 & 0.52 & 40.52 & 116.81 & 3.89 \\ Sample A3 wet & 1 & 87.04 & 86.26 & 0.53 & 43.08 & 121.10 & 3.75 \\ Sample A4 wet & 1 & 95.67 & 83.21 & 0.52 & 40.28 & 122.78 & 3.85 \\  & 2 & 96.24 & 86.32 & 0.53 & 43.02 & 121.48 & 4.14 \\  & 3 & 102.42 & 81.23 & 0.51 & 38.38 & 122.67 & 3.93 \\  & 4 & 96.56 & 85.22 & 0.52 & 41.91 & 121.36 & 4.05 \\ Average A4 & & 97.72 & 84.00 & 0.52 & 40.90 & 122.07 & 3.99 \\ \hline \end{tabular}
\end{table}
Table 2: Summary of the electrical data for each strike on sample A. Legend: \(T_{F}\) = fault duration; \(V_{R}\) = root mean square (RMS) voltage during the fault; \(I_{R}\) = RMS current during the fault; \(P\) = mean fault power; \(\hat{p}\) = peak instantaneous power; \(E\)= total fault energy.  
Figure 6: Static tridimensional spatial image of the spark discharge on sample A provided by a photo camera.