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  • 1
    In: Acta Physica Sinica, Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences, Vol. 72, No. 13 ( 2023), p. 133401-
    Abstract: Ion energy loss in the interaction between highly charged ions and dense plasma near Bohr velocity energy region is one of the important physical problems in the field of high-energy density physics driven by intense heavy ion beams. Based on the 320 kV experimental platform at the Institute of Modern Physics, Chinese Academy of Sciences, a new experimental setup was built for the research of interaction between ions and laser-produced plasma near the Bohr velocity, where the ion energy loss and charge state distribution can be experimentally investigated. In this paper we introduce the new setup in detail, including the generation and controlling of pulsed ion beam ( ≥ 200 ns); the preparation of high-density laser plasma target (10〈sup〉17〈/sup〉—10〈sup〉21〈/sup〉 cm〈sup〉–3〈/sup〉); the diagnostics of plasma and the developed high energy resolution ion measurement system (〈 1%). In the experiment, the charge distribution of Xe〈sup〉15+〈/sup〉 ions with 4 MeV penetrating through the laser-produced Al plasma target is measured. The charge-state analysis device observes different results without and with the plasma, in which the outgoing Xe ion charge-state changes correspondingly from the 15+ to 10+, thus the electron capture process is believed to be dominant. In addition, the proton energy loss is also measured by using the magnetic spectrometer, showing that the experimental energy loss is about 2.0 keV, 30% higher than those theoretical predictions , which can be attributed to the fact that in the near Bohr velocity energy regime, the first-order Born approximation condition is not valid, thus the Bethe model and SSM model are inapplicable to the experimental results. In future, a systematic study will be performed based on our ions-plasma ineteraction setup, and the energy loss and charge state data will be introduced.
    Type of Medium: Online Resource
    ISSN: 1000-3290 , 1000-3290
    Language: Unknown
    Publisher: Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences
    Publication Date: 2023
    Location Call Number Limitation Availability
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  • 2
    In: Acta Physica Sinica, Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences, Vol. 71, No. 14 ( 2022), p. 145203-
    Abstract: When intense laser pulse irradiates a target surface, the energetic processes of generation and expansion of laser-induced plasma will affect a localized pressure impulse around the irradiation zone. As a result, pulsed laser ablating granular target can drive a physical phenomenon of grain ejection. In this work, taking dry glass beads with different grain sizes as an example of granular targets and using high-speed video camera, we experimentally investigate the grain-size dependent dynamics of grain ejection driven by nanosecond laser pulses. The measured video sequences clearly exhibit that the laser-driven grain ejection process can be separated into two regimes: early-stage fast ejecting process and later-stage slow ejecting process. We find that there exists an obvious grain size effect on the kinetic energy of grains in the early-stage ejecting process. In addition, the temporal evolution of transient ejection of a curtain diameter 〈inline-formula〉〈tex-math id="M6"〉\begin{document}$ D\left(t\right) $\end{document}〈/tex-math〉〈alternatives〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="14-20220243_M6.jpg"/〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="14-20220243_M6.png"/〉〈/alternatives〉〈/inline-formula〉 corresponding to the later-stage ejecting process obeys the well-known “point source” law, 〈inline-formula〉〈tex-math id="M7"〉\begin{document}$ {D\left(t\right)=\alpha t}^{\beta } $\end{document}〈/tex-math〉〈alternatives〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="14-20220243_M7.jpg"/〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="14-20220243_M7.png"/〉〈/alternatives〉〈/inline-formula〉, where both parameters 〈inline-formula〉〈tex-math id="M8"〉\begin{document}$ \alpha $\end{document}〈/tex-math〉〈alternatives〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="14-20220243_M8.jpg"/〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="14-20220243_M8.png"/〉〈/alternatives〉〈/inline-formula〉 and 〈inline-formula〉〈tex-math id="M9"〉\begin{document}$ \beta $\end{document}〈/tex-math〉〈alternatives〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="14-20220243_M9.jpg"/〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="14-20220243_M9.png"/〉〈/alternatives〉〈/inline-formula〉 depend on grain size. The observations mentioned above can be reasonably explained by considering the grain size dependent efficiency of impulse coupling between grain and plasma flow and plasma features generated by interaction of laser pulse with granular targets. These experimental results improve the understanding of the mechanism of laser-driven grain ejection.
    Type of Medium: Online Resource
    ISSN: 1000-3290 , 1000-3290
    Language: Unknown
    Publisher: Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences
    Publication Date: 2022
    Location Call Number Limitation Availability
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  • 3
    In: Acta Physica Sinica, Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences, Vol. 73, No. 7 ( 2024), p. 073401-
    Abstract: Partially ionized plasma contains the bound electrons, which have an effect on the instability of the plasma. The evolution process of bound electron density cannot be obtained by using the existing optical method used for diagnosing the free electron density. In this work, we carry out a high-precision experiment: the energy loss of a 100 keV proton beam penetrating through the partially ionized hydrogen plasma target is measured on the platform of ion beam-plasma interaction at the Institute of Modern Physics, Chinese Academy of Sciences. The bound electron density is obtained according to the energy loss model of Bethe theory. The free electron density is measured by laser interferometry and the electron tempercture is obtained from the measured spectrum ( 〈 i 〉 T 〈 /i 〉 〈 sub 〉 e 〈 /sub 〉 = 0.68 eV; 〈 i 〉 n 〈 /i 〉 〈 sub 〉 fe 〈 /sub 〉 = 2.41×10 〈 sup 〉 17 〈 /sup 〉 cm 〈 sup 〉 –2 〈 /sup 〉 ). It is found that the bound electron density decreases during 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, thus providing a new way to solve the problem about measuring the bound electron density in partially ionized plasma. A COMSOL simulation reveals that the high-temperature free electrons will be ejected quickly out of the plasma area through a mechanical diaphragm, thus reducing the total number of free electrons. In order to maintain a relatively high degree of ionization in this plasma, in principle, more and more bound electrons are ionized into free electrons, the density of bound electrons decreases correspondingly. The simulation result accords well with our experimental data. Based on this finding, more detailed plasma target parameter is obtained, which is helpful in deepening the understanding of the interaction process between ion beam and plasma. In future, more researches of low low-energy highly-charged ions-plasma interaction will be conducted.
    Type of Medium: Online Resource
    ISSN: 1000-3290 , 1000-3290
    Language: Unknown
    Publisher: Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences
    Publication Date: 2024
    Location Call Number Limitation Availability
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