High voltage pulsed glow discharge was introduced into the research of inner surface modification to improve the uniformity of implantation dose and depth.The plasma parameter was studied by probe and OES.Ion implantation was performed in a special tube under nitrogen atmosphere.The results showed that continuous plasma could be obtained on the inner surface

and atom in excitation was the majority state in the argon plasma while the N2+ was the majority in the nitrogen plasma.The plasma density increased with the voltage.At 10?15 kV

the argon plasma density increased by about 4 times and the nitrogen plasma density increased by 2 times.Uniform modification layer was obtained on the inner surface of a cylinder of Φ56 mm.The depth reached 16.9 nm and the dose homogeneity was 87.34% at 15 kV and 1.5 Pa.