Experimental study on the full cycle evolution of high-intensity atmospheric dc arc discharge from breakdown to extinguishment

In this study, the spatiotemporal evolution of full cycle of high-intensity dc argon arc discharge at atmospheric pressure is investigated by using a transferred arc device, which is easy to be directly observed in the experiment. Combining the voltage and current waveforms with high-speed images, the full cycle evolution process of high-intensity atmospheric dc arc can be divided into five different stages: breakdown pulse stage, cathode heating stage, current climbing stage, stable arc discharge stage, and finally arc extinguishing stage. The characteristics of each different stage are analyzed in detail through the electrical properties, high-speed pictures, and spectroscopic measurements. The results show that the strong luminescence region develops from the vicinity of cathode and anode to the middle in the breakdown pulse stage, which is explained from the spatiotemporal evolution of distributions of excited argon atom and ions. The development velocity of emission intensity of argon ions is mainly determined by the dominant stepwise ionization process. Then the cathode heating stage appears with many bright and nonuniformly distributed light spots on the cathode surface, and the electron emission mechanism of cathode gradually changes to the thermionic emission as the surface temperature rises. With the increase of arc current, the discharge channel significantly expands, then becomes stable due to the increment of the Lorentz force. The characteristics of arc extinguishing stage are clarified in terms of the decay of charged particles density.

Figure 1

Schematic of the experimental setup.

Figure 2

The waveform of the high-voltage pulse.

Figure 3

Spatiotemporal evolution of full cycle of high intensity dc arc.

Figure 4

Evolution of the discharge channel in the breakdown pulse stage.

Figure 5

Voltage and current waveforms in the breakdown pulse stage.

Figure 6

Spatiotemporal evolution process of the discharge channel.

Figure 7

Spatiotemporal evolution of the emission intensity of excited argon atoms and ions at the central wavelengths of 696 and 375 nm, respectively, in the breakdown pulse stage.

Figure 8

Evolution of the discharge channel in the cathode heating stage.

Figure 9

Heating effect of cathode spots on cathode.

Figure 10

Evolution of the discharge channel in the current climbing stage.

Figure 11

Spatiotemporal evolution of the emission intensity of excited argon atoms (a) and ions (b) at the central wavelengths of 696 nm and 375 nm respectively in the current climbing stage.

Figure 12

Evolution of the discharge channel in the arc extinguishing stage.

Figure 13

Spatiotemporal evolution of the discharge channel in the arc extinguishing stage, (a) the entire arc extinguishing stage, (b) the partial enlarged view in red box.

Figure 14

The correlation between discharge area and arc current.

Figure 15

Spatiotemporal evolution of the emission intensity of excited argon atoms (a) and ions (b) at the central wavelengths of 696 and 375 nm, respectively, in the arc extinguishing stage.