Arc appearances and changing characteristics can be reflected from the arc images. In order to obtain the states of the arc and the influencing factors to them

a lower current flexible model prototype with two observation windows is adopted

the arc appearance in different gases are captured and compared

and the variations of the arc voltage are analyzed. The research shows that arc radiuses and arc brightness decrease with the arc current getting lower

arc voltage and arc brightness increase with the filling gas pressure increasing. The enlargement of the contact distance makes the increase of the arc length and leads to the rising of the arc voltage.CO

2

and N

2

arcs are burning more unstably

the spurt power of the hot gas caused by the jets is larger in N

2

arc

and the effect of the contact distance is remarkable to the CO

2

arc. The analysis method assisted by the arc images gives a reference for understanding the experimental phenomena and provides a support for researching the arc characteristics of the environment-friendly gases.