关键词: 低能电子/
全角分布/
玻璃毛细管/
高电荷态离子
English Abstract
Dynamics of slow electrons transmitting through straight glass capillary and tapered glass capillary
Wan Cheng-Liang1,Li Peng-Fei1,
Qian Li-Bing1,
Jin Bo1,
Song Guang-Yin1,
Gao Zhi-Min2,
Zhou Li-Hua1,
Zhang Qi1,
Song Zhang-Yong3,
Yang Zhi-Hu3,
Shao Jian-Xiong1,
Cui Ying1,
Reinhold Schuch4,
Zhang Hong-Qiang1,
Chen Xi-Meng1
1.School of Nuclear Science and Technology, Lanzhou University, Lanzhou 730000, China;
2.Nuclear and Radiation Safety Bureau of Gansu Province, Lanzhou 730000, China;
3.Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China;
4.Physics Department, Stockholm University, S-10691 Stockholm, Sweden
Fund Project:Project supported by the National Natural Science Foundation of China (Grant Nos. 11475075, 11104125).Received Date:03 March 2016
Accepted Date:22 July 2016
Published Online:05 October 2016
Abstract:It has been found that the transmission rate of the electrons through insulating capillaries as a function of time/incident charge is not the same as that of the ions. The question arises that by using the electrons, if the negative charge patches can be formed to facilitate the transmission of the following electrons, thereby substantiating that the so-called guiding effect works also for electrons. This study aims to observe the time evolutions of the transmission of electrons through a straight glass tube and a tapered glass capillary. This will reveal the details of how and (or) if the negative charge patches can be formed when the electrons transport through them. In this work, a set of MCP/phosphor two-dimensional detection system based on Labview platform is developed to obtain the time evolution of the angular distribution of the transmitted electrons. The pulsed electron beams are obtained to test our detection system. The time evolution of the angular profile of 1.5 keV electrons transmitting through the glass tube/capillary is observed. The transmitted electrons are observed on the detector for a very short time and disappear for a time and then appear again for both the glass tube and tapered glass capillary, leading to an oscillation. The positive charge patches are formed in the insulating glass tube and tapered glass capillary since the secondary electron emission coefficient for the incident energy is larger than 1. It is due to the fact that fast discharge of the deposited charge leads to the increase of the transmission rate, while the fast blocking of the incident electrons due to the deposited positive charge leads to the decrease of the transmission rate. The geometrical configuration of the taper glass capillary tends to make the secondary electrons deposited at the exit part to form the negative patches that facilitate the transmission of electrons. This suggests that if the stable transmission needs to be reached for producing the electron micro-beam by using tapered glass capillaries, the steps must be taken to have the proper grounding and shielding of the glass capillaries and tubes. Our results show a difference in transmission through the insulating capillary between electrons and highly charged ions.
Keywords: low energy electron/
the full angular distribution of the transmitted electrons/
glass capillaries/
highly charged ions
