After adjusting the gas flow rate at an orderly rate of 5, 10, and 15 liter per minute, keeping the distance from the copper ring-shaped to the end of the tube with a length of 15 millimeters, and configure DC power supply to 8.5 kV, the plasma will as shown in fig. 4. Fig. 5, shows the result of the experiment of the gas flow rate at 5 liters per minute were as follows: breakdown voltage was 8.448 kV, the discharge current was 0.00096 – 0.0052 mA, and the plasma length was 24 millimeters. At the gas flow rate of 10 liters per minute, the breakdown voltage was 8.448 kV, the discharge current was 0.00184 – 0.00568 mA, and the plasma length was 27 millimeters. Finally, at the gas flow rate of 15 liters per minute, the breakdown voltage was 8.448 kV, the discharge current was 0.00112 – 0.00496 mA, and the plasma length was 30 millimeters. As shown in the experiment, adjusting the gas flow rate did not influence the discharge voltage and current much, but it did influence the length of plasma significantly