## 3 Results
### Electrical Signal Analysis  
Figure 7 presents the current, voltage, and deposited power waveforms acquired during the discharge process for various dielectric media, revealing key physical phenomena in the metal wire electrical explosion process. The electrical explosion of metal wires in liquid media can be categorized into five typical discharge modes based on distinct characteristics of the current waveform [31]. The current waveforms depicted in Figure 7a indicate that under identical discharge conditions, the discharge modes for different dielectric media consistently exhibit characteristics of mode B. In mode B, the copper wire rapidly vaporizes and undergoes breakdown within the first half-cycle of the oscillating current, subsequently transitioning to the plasma discharge phase. This mode is characterized by the extremely rapid vaporization and breakdown of the copper wire, occurring almost at the initial rise of the current waveform. This swift process results in the transformation of the copper wire into high-temperature, high-density plasma. Analysis of the current waveforms in Figure 7a reveals that, with the exception of copper (II) oxide powder suspension, iron (III) oxide powder suspension, and CO\({}_{2}\)-dissolved liquid, the current variations during discharge are essentially consistent across the other five dielectric media. These three distinctive media exhibit notably lower peak currents of 20.6 kA, 18.8 kA, and 18.5 kA, respectively. However, their discharge durations are prolonged to 270 us, 280 us, and 295 us, representing increases of 35%, 40%, and 47.5%, respectively, compared to the tap water control group. Further examination of the voltage waveforms in Figure 7b confirms patterns consistent with those observed in the current waveforms. The copper (II) oxide powder suspension, iron (III) oxide powder suspension, and CO\({}_{2}\)-dissolved liquid display peak voltages of 7.5 kV, 7.4 kV, and 7 kV, respectively. These values represent reductions of 14.7%, 15.9%, and 19.3% compared to the tap water group's peak voltage of 8.8 kV. Moreover, the occurrence of peak voltage is noticeably delayed, corresponding to the timing of peak current. These observations indicate significant variations in discharge characteristics between the different dielectric media during the electrical explosion process. Analysis of CO\({}_{2}\)-dissolved liquid: The introduction of CO\({}_{2}\) gas into the drill hole is hypothesized to result in gas bubble pulsation during CO\({}_{2}\) dissipation, compressing the surrounding medium and increasing gas volume. This process is believed to elevate pressure within the drill hole. The increased pressure is proposed to delay copper wire vaporization and inhibit discharge channel expansion. Analysis of copper (II) oxide and iron (III) oxide powder suspensions: For these metal oxide suspensions, it is proposed that the electrical explosion energy and radiation products are partially absorbed by the micrometer-sized metal powder particles. This absorption is thought to reduce the energy available in the discharge channel, rendering it insufficient for rapid wire vaporization. Consequently, continued energy input from the storage capacitor is required to maintain the discharge, thereby extending the discharge duration. The differential effects observed between copper (II) oxide and iron (III) oxide powder suspensions are attributed to their distinct melting points: 1446 \({}^{\circ}\)C for copper (II) oxide and 1538 \({}^{\circ}\)C for iron (III) oxide. Under identical discharge conditions, it is hypothesized that copper (II) oxide powder suspension absorbs relatively less energy due to its lower melting point. This difference is proposed as the explanation for the higher peak current observed in copper (II) oxide powder suspension compared to iron (III) oxide powder suspension. Figure 7: Waveforms of electrical explosion signals in different dielectrics.