无定形碳薄膜的二次电子发射特性研究

新一代粒子加速器向着高能量和高亮度方向发展,而储存环中的电子云效应极大地阻碍了粒子束的稳定性,是限制加速器进一步发展的主要制约因素。因此,对于新一代的高能粒子加速器来说,寻找低二次电子发射系数(SEY)的储存环真空室表面材料是至关重要的。研究发现,储存环真空室表面沉积无定形碳薄膜是一种很有潜力的加速器真空室表面处理方法。采用直流磁控溅射的方法,在管道表面沉积了高质量的无定形碳薄膜,并对二次电子发射特性进行了研究,发现在入射电子密度为1×10^-8C/mm^-2的条件下,薄膜的SEY为1.132,说明无定形碳薄膜可以很好地降低二次电子发射,从而抑制电子云效应。

Amorphous Carbon Coating Material with Low Secondary Electron Yield for High Energy Particle Accelerator

We addressed the electron cloud problem in modern high-energy and high-luminosity particle accelerators. The amorphous carbon (a-C) coatings, with low secondary electron yield (SEY) in ultra-high vacuum, were deposited by DC magnetron sputtering on the stainless steel substrate installed on the inner wall of a pipe (Φ86 mm×1000 mm) to be used as the storage ring in the particle accelerator. The influence of the microstructures of the aC coatings and dose of electron beam on SEY was investigated with scanning electron microscopy and X-ray photoelectron spectroscopy. The results show that normally impacted by an e-beam at a dose of 1×10^-8 C/mm^-2, SEY of the highly pure and fairly rough a-C coatings with strong interfacial adhesion was estimated to be 1. 132. We suggest that a-C film may be a promising surface modification material to suppress electron cloud and to enhance the particle beam stability.