Experimental set-up. (a) Schematic illustration of the most relevant parts of the arc generation circuit connected to the sample chamber. A DC–DC converter charged three parallel capacitors (). The ignition coil was protected from the charging voltage of C_arc by the diode D_spark. After C_arc had reached the target voltage, the ignition coil generated a high-voltage peak up to 8 kV and produced an ionized channel between the electrodes (ignition spark). Diode D_spark became conductive, while C_arc was protected by D_arc from the high-voltage peak. After the electrical breakdown, the voltage decreased instantaneously. When the voltage had dropped below the charging voltage of C_arc, the energy stored in C_arc was released into the existing ionized channel, causing a high-energy arc discharge. (b) Sample chamber made of quartz glass. Two tungsten electrodes were embedded into the glass on opposite sides. The sample chamber was loaded with 30 mg of Mg₂SiO₄ particles.