自支撑类金刚石碳剥离膜的制备工艺及其寿命研究

The National Laboratory of Beijing HI-13 Tandem Accelerator is one of important bases for nuclear physics experiments. Recently, with the increasing of accelerated particle beam current and the particles become heavier, better qulity and lifetime of the foils are demanded. The available preparation method of carbon stripper foil (carbon arc technology) can not meet the requirements. Moreover, the short lifetime problem were encountered in the past few years, and lead to the low operating efficiency and high operating costs of HI-13 Tandem Accelerator. The research on the preparation of long lifetime carbon stripper foils is difficulty and hotspot in the world. The project intends to improve the industry coating technology (double 90 bend magnetic filtered cathodic arc plasma) according to our laboratory application. Meantime AC carbon arc technology, stripping technique and relaxation technique are combined. The study on the relationship between bond structure and lifetime of diamond-like carbon stripper foil is breakthrough point, and then the impact coating process on the quality and lifetime of the stripper foil are studied. The best preparation process of long lifetime self-supporting diamond-like carbon stripper foils of about 5μg/cm2 will explored. The long lifetime self-supporting diamond-like carbon stripper foils will be applied to HI-13 tandem accelerator and experimental nuclear physics to solve the current problem of low operating efficiency caused by the short lifetime of stripper foils.

北京HI-13串列加速器国家实验室是我国重要的核物理实验基地之一。近年来，由于核物理实验的需求，在该加速器上引出越来越多的大流强低能重离子束，对剥离膜的质量和寿命提出了更高的要求。目前在串列加速器上使用碳弧法制备的碳剥离膜，用于这些大流强低能重离子的剥离时寿命太短，降低了加速器的整体运行效率，并提高了运行成本。长寿命碳剥离膜的研制一直是国际上研究的热点和难点。本项目拟将工业中的镀膜技术- - 双90 弯管磁过滤阴极弧等离子体- - 根据实验室的应用加以改进，并与交流碳弧技术、脱膜技术和松弛技术相结合，以研究类金刚石碳膜键结构与寿命的关系作为切入点，进而研究镀膜工艺对剥离膜质量和寿命的影响，探索制备质量厚度约为5μg/cm2的长寿命自支撑超薄类金刚石碳剥离膜的最佳工艺，并将大量制备的类金刚石碳剥离膜应用到HI-13串列加速器和实验核物理中去,解决目前加速器因剥离膜寿命短而引起的运行效率低的问题。

近年来，由于核物理实验的需求，在北京HI-13串列加速器上引出越来越多的大流强低能重离子束。过去使用碳弧法制备的碳剥离膜，用于这些大流强低能重离子的剥离时寿命太短，降低了加速器的整体运行效率，并提高了运行成本。本项目将工业中的镀膜技术——双90°弯管磁过滤阴极弧等离子体——根据实验室的应用加于改进，并与交流碳弧技术、脱膜技术和松弛技术相结合，以研究类金刚石碳（DLC）膜键结构与寿命的关系作为切入点，进而研究镀膜工艺对剥离膜质量和寿命的影响，探索制备质量厚度约为5μg/cm2的长寿命自支撑超薄DLC剥离膜的最佳工艺。通过本项目的研究，掌握了制备DLC剥离膜的整套工艺方法，解决了自支撑DLC膜制备中关键的脱膜问题，制备了1500余片DLC剥离膜已经成功用于北京HI-13串列加速器最近两年的需求当中，并取得了良好效果。制得的DLC膜光滑致密、基本不含液滴、为典型的非晶DLC膜、SP3杂化键超过70%（-400 V的基衬偏压对应的DLC膜中含sp3杂化键最高，达到82%）。对于~9Mev、~1μA的63Cu-和197Au-离子束，DLC剥离膜寿命比碳弧碳剥离膜分别至少高4倍和13倍；对于107Ag-、70Ge-、48Ti-、28Si-和127I-离子束，DLC剥离膜寿命比碳剥离膜高2.6～10倍，并且离子越重、束流越强，DLC剥离膜的寿命对比碳剥离膜寿命的优势就越大；DLC剥离膜寿命与sp3杂化键具有一定的正相关性，并随基衬偏压的加大而先升高后降低，-400V的基衬偏压下DLC剥离膜寿命最长。