# Ozone Generation by Surface Dielectric Barrier Discharge
## 2 Experimental Setup and Methods  
The construction of the SDBD generators used in this study is typical of those used in the literature for EHD generation [41; 42; 43; 44]. It is composed of two electrodes placed asymmetrically on the opposite sides of a ceramic plate (1 mm thick) which acts as a dielectric barrier (Figure 1A). We studied three types of SDBD generators, which differ in the geometry of the high-voltage electrode (smooth-edge, serrated and thin-wire electrode). The smooth-edge and serrated high-voltage electrodes and the grounded electrode of the generators were made of 50 \(\upmu\)m thick copper foil, while the thin-wire electrode was made of thin steel wire with a diameter of 50 \(\upmu\)m. The active length of the high-voltage electrodes for all three generators was 75 mm. The experimental setup used to measure the electrical properties of the SDBD discharge, the time-resolved imaging of the discharge plasma and the ozone production yield is shown in Figure 1B. To power the SDBD generators, a high-voltage sine wave (with a voltage (peak-to-peak) ranging from 8 kV to 21.6 kV and a frequency of 1 kHz) was generated using a function generator (Tektronix AFG3101, Tektronix Inc., Beaverton, OR, USA) and a high-voltage amplifier (Trek 40/15). The usable voltage was limited to this range because, at lower voltages, the discharge was not uniform along the entire length of the electrode, and at higher voltages, we observed distortion of the voltage function due to the limitations of the high-voltage amplifier. The voltage function was recorded on an oscilloscope with a Tektronix T6015A (Tektronix Inc., Beaverton, OR, USA) high-voltage probe, and the SDBD discharge current was determined from the voltage drop across an R = 100 \(\Omega\) resistor mounted on a grounding wire. To measure the power dissipated in the SDBD discharge, we used a measuring capacitor method (sometimes also called the Lissajous figures method) [45; 46; 47]. In this method, a high-voltage capacitor (C = 0.8 nF) is placed between the grounded electrode and the electrical ground (interchangeably with the measuring resistor) to measure the transported charge. The Lissajous curves were recorded on the oscilloscope by plotting the transported charge on the vertical axis and the applied voltage on the horizontal axis. The power dissipated in the discharge in one voltage cycle was calculated as the area limited by the Lissajous figure multiplied by the frequency of the voltage wave function (1 kHz). The investigation of the discharge plasma morphology was performed using an Andor iStar DH734 (Andor Technology Ltd., Belfast, UK) fast-gated intensified ICCD camera equipped with a 10\(\times\) microscope lens, which we used to capture time-resolved images of the discharge [44,48]. The observation area was a 6 mm \(\times\) 6 mm square focused on the discharge edge of the electrode. The ICCD camera was triggered by the signal generated by the function generator, which allowed us to synchronize the camera with the voltage waveform and capture sets of images at various time delays with respect to the voltage waveform. A set of 200 images was recorded in each measurement. Figure 1: (**A**) geometry of SDBD generators; (**B**) experimental setup. To measure the ozone yield, the SDBD generator was placed inside a chamber (120 mm \(\times\) 130 mm \(\times\) 700 mm) that was open on one side and with an exhaust air system mounted on the opposite side. Clean air was first forced into the chamber (by the small fan mounted on the exhaust tube), then through the Delta Ohm flow sensor with an AP472-S2 vane probe and an ozone meter (Aeroqual 300--Aeroqual Inc., Auckland, New Zeland, with an electrochemical probe, model EOZ 0-10 ppm), and, finally, out of the room. The ozone yield was calculated based on the ozone concentration and the total airflow rate in the exhaust tube (60 mm in diameter) at the exit of the measurement chamber.