Self-organized pattern on the surface of a metal anode in low-pressure DC discharge

Self-organization phenomena on the surface of a metal electrode in low-pressure DC discharge is studied.In this paper,we carry out laboratory investigations of self-organization in a low-pressure test platform for 100-200 mm rod-plane gaps with a needle tip,conical tip and hemispherical tip within 1-10 kPa.The factors influencing the pattern profile are the pressure value,gap length and shape of the electrode,and a variety of pattern structures are observed by changing these factors.With increasing pressure,first the pattern diameter increases and then decreases.With the needle tip,layer structure,single-ring structure and double-ring structure are displayed successively with increasing pressure.With the conical tip,the ring-like structure gradually forms separate spots with increasing pressure.With the hemispherical tip,there are anode spots inside the ring structure.With the increase of gap length,the diameter of the self-organized pattern increases and the profile of the pattem changes.The development process of the pattern contains three key stages:pattern enlargement,pattern stabilization and pattern shrink.