A twin-wave quadrature interferometer for diagnostics of pulsed processes in hydrogen and erosion plasma

Kuznetsov, A. P.; Голубев, А. А.; Kozin, G. I.; Mutin, T. Y.; Savelov, A. S.; Fertman, A.

doi:10.1134/s0020441206020151

Cited by 7 publications

(2 citation statements)

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“…在实验过程中, 质子束的脉冲长度约为200 ns, 通过调节等离子体、离子束与探测器三者之间的时序关系, 精确测量了100 keV 脉冲质子束与不同状态(不同温度与电子密度)的部分电离氢等离子体靶作用后的离子能损数据, 考虑到束斑宽度、能量展宽等问题, 该能损数据的误差约为5%. 抑制放电电流产生的外加磁场的干扰 [17,18] ; 真空系统采用二级差分结构, 在0.5 -5 mbar (1 bar = 10 5 Pa)的工作气压条件下保证加速器束线真空维持在10 -7 mbar量级.…”

Section: 实验装置与等离子体参数诊断unclassified

Diagnosis of bound electron density by measuring energy loss of proton beam in partially ionized plasma target

Chen,

Wang,

Zhou

et al. 2024

Acta Phys. Sin.

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Partially ionized plasma contains the bound electrons aspect which have an impact on the instability of the plasma, among other things. The evolution process of bound electron density cannot be obtained from the popular method applying for diagnosis of the free electron density aspect, in which the existing optical diagnostics fail. In this paper, we introduce a high-precision experiment: the energy loss of a 100 keV proton beam penetrating through the partially ionized hydrogen plasma target was measured based on the platform of ion beam - plasma interaction at the Institute of Modern Physics, Chinese Academy of Sciences. The bound electron density is figured out according to the energy loss model of Bethe theory, the free electron density information obtained by laser interferometry diagnosis and the electron tempercture measureed by spectrum (Te=0.68 eV; nfe =2.41×1017 cm-2). It is found that the bound electron density decreases with the plasma lifetime. The diagnosis of bound electron density by measuring energy loss of ion beam has the advantages of on-line, in-situ and high resolution, and provides a new way to solve the problem of the bound electron density in partially ionized plasma. A COMSOL simulation reveals that the high-temperature free electrons quickly spray out of the plasma area through a mechanical diaphragm, thus the total number of free electrons decreases. In order to maintain a relatively high degree of ionization in this plasma, in principle, more and more bound electrons are ionized to be free electrons, correspondingly the density of bound electrons decreases. The simulation result agrees well with our experimental data. Based on this finding, more detailed plasma target parameter is provied, which is helpful to deepen the understanding of the interaction process between ion beam and plasma. In future, more research work about lowly energy highly charged ions-plasma interaction will be introduced.

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Section: 实验装置与等离子体参数诊断unclassified