中文摘要：

纳秒脉冲弥散放电能够在大气压下产生高功率密度、高电子能量的低温等离子体。为了研究弥散放电等离子体在金属材料表面改性的作用，利用上升沿约150ns、脉宽约300ns的MPC-50D纳秒脉冲电源在大气压下（空气）管一板电极之间产生弥散放电，寻找最佳弥散放电参数，并对金属Cu表面进行了弥散处理。研究结果表明：随着重复频率的增加，弥散放电增强，瞬时功率增大，沉积能量增多。当施加电压为31kV，重复频率为800Hz，间隙距离为3cm时，得到最佳的弥散放电效果。此外，采用发射光谱检测到空气中弥散放电中N2（C→B，0-0）的第二正带系和N2＋（B→X20-O）的第一负带系。采用大气压弥散放电等离子体对金属cu表面处理的结果显示处理后的Cu表面出现孔径约0．5μm的熔孔；Cu的亲水性及表面能有明显提高，在处理90S后趋于饱和。显微硬度测量结果表明，表层硬度在等离子体处理时间480S后提高约26．5％。

英文摘要：

Nanosecond-pulse diffuse discharges can generate non-thermal plasmas with high power density and high electron energy at atmospheric pressure. In order to study the surface modification of metal surface using diffuse dis- charges, a diffuse discharge with a tube-to-plane electrode geometry was produced to find the optimal diffuse discharge parameters. The discharge was excited by an MPC-50D nanosecond-pulse power with a rise time of about 150 ns and full width at half maximum （FWHM） of about 300 ns in atmospheric pressure air, and then it was used for Cu surface modification. The experimental results showed that the diffuse discharge intensity, instantaneous power and deposition energy increased with the pulse repetition frequency （PRF）. Moreover, the best performance of diffuse discharge occurred when the applied voltage was 31 kV, the PRF was 800 Hz and the gap distance was 3 cm. Furthermore, emission spectrum showed that the second positive system of N2 （C→B, 0-0） and the first negative system of N2＋ （B→X2 0-0） were detected in air. The results of copper surface modification showed that plasma treatment would generate 0.5 μm-diameter melt holes on the copper surface. Both the hydrophilic and surface energy were significantly enhanced after the plasma treat- ment and reached a saturated value after 90 s. In addition, micro-hardness measurements showed that the surface hardness increased by about 26.5% after 480 s treatment.