16 keV C-离子在锥形玻璃管中的输运过程

Study on transport process of 16 keV C-ions in tapered glass capillary:Role of capillary tilt angles

鉴于经锥形玻璃管聚焦的离子束在微纳加工、微区分析以及辐照生物医学等领域具有广阔的应用前景,本文研究了16 keV C^(-)在不同倾斜角度的锥形玻璃管中输运过程.实验发现当处于0°倾斜角度时,出射粒子由核区和晕区构成,核区是从锥形管后锥孔中直接出射,未与锥形管内壁之间发生电荷交换,主要成分为C^(-)离子.晕区是C^(-)与锥形管内壁发生部分电荷交换作用,由C^(-)和C^(0)构成.当倾斜角度为1°时,出射离子由两部分组成:C^(0)原子束斑和C-离子束斑,未出现核区.出射核区的离子方向始终保持在入射粒子方向,与锥形管倾斜角度无关.随着锥形管不断倾斜,相对透射率不断减小,C^(0)束斑占比增加,C^(-)束斑占比减小.锥形管对入射离子有聚焦效应.本实验弥补了低能负离子在锥形管运输过程研究的欠缺,有助于聚焦离子束的后续开发应用.

The tapered glass capillaries have been widely used in physics,biology,materials.The features of ions transmitted through the insulating tapered glass capillary manifest themselves mainly in the interaction between positive ions and tapered glass capillary,However,the transmission process of negative ions in tapered glass capillary has been studied scarcely so far.In the present study,we measure the properties of 16 keV C^(-) ions transmitted through the tapered glass capillary,such as the two-dimensional spectral distribution,the relative transmission rate,the centroid angle,the charge state purity and the full width at half maximum of the transmitted particles.As the tapered glass capillary tilt angle is equal to 0°,the transmitted particles are composed of three components,i.e.the core,the C^(-) of halo and the C^(0)of halo.As the tilt angle is 1°,the transmitted particles are composed of two components,i.e.C^(-) and C^(0).As the tilt angle is>1°,there is no core region,the transmitted particles are composed of two components,i.e.C^(-) and C^(0).No matter how the tilt angle changes,the centroid angles of core are always along the direction of the incident ions,independent of the tilt angels.And the centroid angles of transmitted C^(-) and C^(0)are always along the direction of the capillary axis.The transmission processes of 16 keV C-ions in tapered glass capillary with different tilting angles are analyzed qualitatively.When the tilting angle is small(0°-1°),the C-ions are directly traveling straight through the back cone hole of tapered glass capillary,which are mainly composed of C^(-) ions.When the tilt angle is large(>1°),the C-ions cannot directly travel straight through the back cone hole of the tapered glass capillary,and the core region does not appear.Due to the guiding effect of the negative charges deposited on inner wall of tapered glass capillary,the transmitted C^(-) ions are located around the direction of the capillary axis.The tapered glass capillary has a focusing effect on the incident ions.This experiment covers the lack of the studies of low-energy negative ions transmitted through tapered capillary and helps to strengthen the understanding of the transmission process of low-energy ions transmitted through tapered capillary.