Proton stopping power measurements in warm dense matter at low velocity projectile ratio
ORAL · Invited
Abstract
Ion stopping power in high energy density (HED) plasmas is of great interest for fundamental science and is important in many areas of inertial confinement fusion, including central hot spot ignition, fast ignition, and heavy ion fusion. Theoretical modelling of ion stopping power in HED plasmas is a difficult task and there is little experimental data to validate and benchmark models, contributing to large discrepancies amongst them. The modelling of stopping power in Warm Dense Matter (WDM) is particularly challenging due to electron degeneracy and coupling, which modify the Coulomb logarithm characterizing the collisions in the plasma. While a number of experimental studies have been performed on ion stopping power in classical plasmas, experimental database in WDM is essentially missing. In addition, the low velocity stopping power regime where vp (ion velocity) ~ vth (electron thermal velocity) remains virtually unexplored.
Here, we report the first proton energy loss measurements in warm dense plasma at low projectile velocities vp/ vth ≈ 3-10 [1]. The experiment was performed at CLPU VEGA-II laser facility by using a novel high repetition rate platform [2]. The platform is based on the energy selection of a quasi-monoenergetic, short time-duration, proton beam of 500 keV from a broadband proton spectrum. A WDM with a temperature of around 10 eV was generated by femtosecond laser-heating of a thin carbon foil and characterized using two independent spectroscopy diagnostics. Our energy-loss data demonstrate a significant deviation of the stopping power from classical models in this regime. In particular, we show that our results are in closest agreement with recent first-principles simulations based on time-dependent density functional theory [3,4].
[1] S. Malko et al, Nat. Commun.13, 2893 (2022)
[2] J. Apiñaniz et al. Sci. Rep. 11, 6881 (2021)
[3] A. J. White et al., Phys. Rev. B 98, 144302 (2018)
[4] A. J. White et al., Phys. Rev. Lett. 125, 055002 (2020)
Here, we report the first proton energy loss measurements in warm dense plasma at low projectile velocities vp/ vth ≈ 3-10 [1]. The experiment was performed at CLPU VEGA-II laser facility by using a novel high repetition rate platform [2]. The platform is based on the energy selection of a quasi-monoenergetic, short time-duration, proton beam of 500 keV from a broadband proton spectrum. A WDM with a temperature of around 10 eV was generated by femtosecond laser-heating of a thin carbon foil and characterized using two independent spectroscopy diagnostics. Our energy-loss data demonstrate a significant deviation of the stopping power from classical models in this regime. In particular, we show that our results are in closest agreement with recent first-principles simulations based on time-dependent density functional theory [3,4].
[1] S. Malko et al, Nat. Commun.13, 2893 (2022)
[2] J. Apiñaniz et al. Sci. Rep. 11, 6881 (2021)
[3] A. J. White et al., Phys. Rev. B 98, 144302 (2018)
[4] A. J. White et al., Phys. Rev. Lett. 125, 055002 (2020)
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Publication: S. Malko et al, Nat. Commun.13, 2893 (2022)
J. Apiñaniz et al. Sci. Rep. 11, 6881 (2021)
V. Ospina-Bohorquez et al. manuscript in preparation for submission to HPSLE
Presenters
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Sophia Malko
- Princeton Plasma Physics Laboratory