Fig. 1. Experimental setup.

Fig. 2. Examples of current (a) and voltage (b) oscilloscope signals of copper wire explosions at different initial voltages: (1) 20 kV (the energy deposited up to the moment of secondary breakdown is 17 J/mg); (2) 15 kV (9.7 J/mg); (3) 10 kV (7.7 J/mg).

Fig. 3. Shadow image (a) and oscilloscope signals (b) of copper wire explosion (wire diameter 25 μm, length 12 mm). U₀ = 20 kV, without current pause.

Fig. 4. Shadow image (a) and scope signals (b) of copper wire explosion (wire diameter 25 μm, length 12 mm). U₀ = 10 kV, with current pause.

Fig. 5. Shadow image of copper wire explosion (wire diameter 25 μm, length 12 mm) at 135 ns after beginning of secondary breakdown. U₀ = 10 kV, linear breakdown channel.

Fig. 6. Shadow image of copper wire explosion (wire diameter 25 μm, length 12 mm) at 80 and 100 ns after beginning of secondary breakdown. U₀ = 15 kV, spiral breakdown channel.

Fig. 7. Shadow image of copper wire explosion (wire diameter 25 μm, length 12 mm) at 175, 205, and 245 ns after beginning of secondary breakdown. U₀ = 10 kV, axial breakdown channel. All three images were obtained in one shot.

Fig. 8. Shadow image of copper wire explosion (wire diameter 25 μm, length 12 mm) at moments 25 ns before and 5 ns and 45 ns after beginning of secondary breakdown. U₀ = 10 kV, axial breakdown channel. All three images were obtained in one shot.

Fig. 9. (a) Current oscilloscope signals in shots with linear breakdowns and (b) current pause durations versus deposited energies for shots with different breakdown types at an initial voltage of 15 kV (copper wire of diameter 25 μm).

Fig. 10. Current (a) and voltage (b) oscilloscope signals obtained under identical experimental conditions (15 kV, copper wire of diameter 25 μm).