Title: Proton stopping measurements at low velocity in warm dense carbon
Abstract
Ion stopping in warm dense matter is a process of fundamental importance for the understanding of the properties of dense plasmas, the realization and the interpretation of experiments involving ion-beam-heated warm dense matter samples, and for inertial confinement fusion research. The theoretical description of the ion stopping power in warm dense matter is difficult notably due to electron coupling and degeneracy, and measurements are still largely missing. In particular, the low-velocity stopping range, that features the largest modelling uncertainties, remains virtually unexplored. Here, we report proton energy-loss measurements in warm dense plasma at unprecedented low projectile velocities. Our energy-loss data, combined with a precise target characterization based on plasma-emission measurements using two independent spectroscopy diagnostics, 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.
Khan, Ahtesham Ullah; Nelson, Nicholas P.; Culberson, Wesley S.; DeWerd, Larry A.(
, Medical Physics)
AbstractBackground
In a recent study, we reported beam quality correction factors,fQ, in carbon ion beams using Monte Carlo (MC) methods for a cylindrical and a parallel‐plate ionization chamber (IC). A non‐negligible perturbation effect was observed; however, the magnitude of the perturbation correction due to the specific IC subcomponents was not included. Furthermore, the stopping power data presented in the International Commission on Radiation Units and Measurements (ICRU) report 73 were used, whereas the latest stopping power data have been reported in the ICRU report 90.
Purpose
The aim of this study was to extend our previous work by computingfQcorrection factors using the ICRU 90 stopping power data and by reporting IC‐specific perturbation correction factors. Possible energy or linear energy transfer (LET) dependence of thefQcorrection factor was investigated by simulating both pristine beams and spread‐out Bragg peaks (SOBPs).
Methods
The TOol for PArticle Simulation (TOPAS)/GEANT4 MC code was used in this study. A 30 × 30 × 50 cm3water phantom was simulated with a uniform 10 × 10 cm2parallel beam incident on the surface. A Farmer‐type cylindrical IC (Exradin A12) and two parallel‐plate ICs (Exradin P11 and A11) were simulated in TOPAS using the manufacturer‐provided geometrical drawings. ThefQcorrection factor was calculated in pristine carbon ion beams in the 150–450 MeV/u energy range at 2 cm depth and in the middle of the flat region of four SOBPs. ThekQcorrection factor was calculated by simulating thefQocorrection factor in a60Co beam at 5 cm depth. The perturbation correction factors due to the presence of the individual IC subcomponents, such as the displacement effect in the air cavity, collecting electrode, chamber wall, and chamber stem, were calculated at 2 cm depth for monoenergetic beams only. Additionally, the mean dose‐averaged and track‐averaged LET was calculated at the depths at which thefQwas calculated.
Results
The ICRU 90fQcorrection factors were reported. Thepdiscorrection factor was found to be significant for the cylindrical IC with magnitudes up to 1.70%. The individual perturbation corrections for the parallel‐plate ICs were <1.0% except for the A11pcelcorrection at the lowest energy. ThefQcorrection for the P11 IC exhibited an energy dependence of >1.00% and displayed differences up to 0.87% between pristine beams and SOBPs. Conversely, thefQfor A11 and A12 displayed a minimal energy dependence of <0.50%. The energy dependence was found to manifest in the LET dependence for the P11 IC. A statistically significant LET dependence was found only for the P11 IC in pristine beams only with a magnitude of <1.10%.
Conclusions
The perturbation andkQcorrection factor should be calculated for the specific IC to be used in carbon ion beam reference dosimetry as a function of beam quality.
Walsh, Brian M.; Hull, Arthur J.; Agapitov, Oleksiy; Mozer, Forrest S.; Li, Haimeng(
, Journal of Geophysical Research: Space Physics)
Abstract
A survey of electrons with energies between ∼1 eV and 30 keV was conducted using measurements from the THEMIS spacecraft over radial distances between 3 and 12 Earth radii. Two distinct populations are observed, one with a peak energy near 10 eV and one at approximately 1 keV. These populations are present 88% of the time in the magnetosphere. The warm population (∼10 eV) is generally more dense (∼1 cm−3) and extends across the dayside. These warm electron characteristics are similar to the ion warm plasma cloak. The hot distribution (∼1 keV) peaks in number density (∼0.2 cm−3) near midnight and into the morning sector. Since the populations are transported through different evolutionary paths, there are spatial regions within the magnetosphere where the density ratio of the populations (warm to hot,nw/nh) is much larger or smaller than unity. AtLshells greater than ∼6, near midnight and into the dawn sector, the density of the hot population is close to a factor of 10 larger than the warm populations. In other regions, the warm electron population is typically slightly more dense (∼2×) than the hot population.
Kronberg, E. A.; Grigorenko, E. E.; Malykhin, A.; Kozak, L.; Petrenko, B.; Vogt, M. F.; Roussos, E.; Kollmann, P.; Jackman, C. M.; Kasahara, S.; et al(
, Journal of Geophysical Research: Space Physics)
Abstract
The dissipation processes which transform electromagnetic energy into kinetic particle energy in space plasmas are still not fully understood. Of particular interest is the distribution of the dissipated energy among different species of charged particles. The Jovian magnetosphere is a unique laboratory to study this question because outflowing ions from the moon Io create a high diversity in ion species. In this work, we use multispecies ion observations and magnetic field measurements by the Galileo spacecraft. We limit our study to observations of plasmoids in the Jovian magnetotail, because there is strong ion acceleration in these structures. Our model predicts that electromagnetic turbulence in plasmoids plays an essential role in the acceleration of oxygen, sulfur, and hydrogen ions. The observations show a decrease of the oxygen and sulfur energy spectral indexγat ∼30 to ∼400 keV/nuc with the wave power indicating an energy transfer from electromagnetic waves to particles, in agreement with the model. The wave power threshold for effective acceleration is of the order of 10 nT2Hz−1, as in terrestrial plasmoids. However, this is not observed for hydrogen ions, implying that processes other than wave‐particle interaction are more important for the acceleration of these ions or that the time and energy resolution of the observations is too coarse. The results are expected to be confirmed by improved plasma measurements by the Juno spacecraft.
Angermeier, William A.; Scheiner, Brett S.; Shaffer, Nathaniel R.; White, Thomas G.(
, Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences)
Warm dense matter is a material state in the region of parameter space connecting condensed matter to classical plasma physics. In this intermediate regime, we investigate the significance of non-adiabatic electron-ion interactions upon ion dynamics. To disentangle non-adiabatic from adiabatic electron-ion interactions, we compare the ion self-diffusion coefficient from the non-adiabatic electron force field computational model with an adiabatic, classical molecular dynamics simulation. A classical pair potential developed through a force-matching algorithm ensures the only difference between the models is due to the electronic inertia. We implement this new method to characterize non-adiabatic effects on the self-diffusion of warm dense hydrogen over a wide range of temperatures and densities. Ultimately we show that the impact of non-adiabatic effects is negligible for equilibrium ion dynamics in warm dense hydrogen. This article is part of the theme issue ‘Dynamic and transient processes in warm dense matter’.
Sprenkle, R. Tucker; Silvestri, L. G.; Murillo, M. S.; Bergeson, S. D.(
, Nature Communications)
Abstract New facilities such as the National Ignition Facility and the Linac Coherent Light Source have pushed the frontiers of high energy-density matter. These facilities offer unprecedented opportunities for exploring extreme states of matter, ranging from cryogenic solid-state systems to hot, dense plasmas, with applications to inertial-confinement fusion and astrophysics. However, significant gaps in our understanding of material properties in these rapidly evolving systems still persist. In particular, non-equilibrium transport properties of strongly-coupled Coulomb systems remain an open question. Here, we study ion-ion temperature relaxation in a binary mixture, exploiting a recently-developed dual-species ultracold neutral plasma. We compare measured relaxation rates with atomistic simulations and a range of popular theories. Our work validates the assumptions and capabilities of the simulations and invalidates theoretical models in this regime. This work illustrates an approach for precision determinations of detailed material properties in Coulomb mixtures across a wide range of conditions.
Malko, S., Cayzac, W., Ospina-Bohórquez, V., Bhutwala, K., Bailly-Grandvaux, M., McGuffey, C., Fedosejevs, R., Vaisseau, X., Tauschwitz, An., Apiñaniz, J. I., De Luis Blanco, D., Gatti, G., Huault, M., Hernandez, J. A. Perez, Hu, S. X., White, A. J., Collins, L. A., Nichols, K., Neumayer, P., Faussurier, G., Vorberger, J., Prestopino, G., Verona, C., Santos, J. J., Batani, D., Beg, F. N., Roso, L., and Volpe, L. Proton stopping measurements at low velocity in warm dense carbon. Nature Communications 13.1 Web. doi:10.1038/s41467-022-30472-8.
Malko, S., Cayzac, W., Ospina-Bohórquez, V., Bhutwala, K., Bailly-Grandvaux, M., McGuffey, C., Fedosejevs, R., Vaisseau, X., Tauschwitz, An., Apiñaniz, J. I., De Luis Blanco, D., Gatti, G., Huault, M., Hernandez, J. A. Perez, Hu, S. X., White, A. J., Collins, L. A., Nichols, K., Neumayer, P., Faussurier, G., Vorberger, J., Prestopino, G., Verona, C., Santos, J. J., Batani, D., Beg, F. N., Roso, L., & Volpe, L. Proton stopping measurements at low velocity in warm dense carbon. Nature Communications, 13 (1). https://doi.org/10.1038/s41467-022-30472-8
Malko, S., Cayzac, W., Ospina-Bohórquez, V., Bhutwala, K., Bailly-Grandvaux, M., McGuffey, C., Fedosejevs, R., Vaisseau, X., Tauschwitz, An., Apiñaniz, J. I., De Luis Blanco, D., Gatti, G., Huault, M., Hernandez, J. A. Perez, Hu, S. X., White, A. J., Collins, L. A., Nichols, K., Neumayer, P., Faussurier, G., Vorberger, J., Prestopino, G., Verona, C., Santos, J. J., Batani, D., Beg, F. N., Roso, L., and Volpe, L.
"Proton stopping measurements at low velocity in warm dense carbon". Nature Communications 13 (1). Country unknown/Code not available: Nature Publishing Group. https://doi.org/10.1038/s41467-022-30472-8.https://par.nsf.gov/biblio/10367568.
@article{osti_10367568,
place = {Country unknown/Code not available},
title = {Proton stopping measurements at low velocity in warm dense carbon},
url = {https://par.nsf.gov/biblio/10367568},
DOI = {10.1038/s41467-022-30472-8},
abstractNote = {Abstract Ion stopping in warm dense matter is a process of fundamental importance for the understanding of the properties of dense plasmas, the realization and the interpretation of experiments involving ion-beam-heated warm dense matter samples, and for inertial confinement fusion research. The theoretical description of the ion stopping power in warm dense matter is difficult notably due to electron coupling and degeneracy, and measurements are still largely missing. In particular, the low-velocity stopping range, that features the largest modelling uncertainties, remains virtually unexplored. Here, we report proton energy-loss measurements in warm dense plasma at unprecedented low projectile velocities. Our energy-loss data, combined with a precise target characterization based on plasma-emission measurements using two independent spectroscopy diagnostics, 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.},
journal = {Nature Communications},
volume = {13},
number = {1},
publisher = {Nature Publishing Group},
author = {Malko, S. and Cayzac, W. and Ospina-Bohórquez, V. and Bhutwala, K. and Bailly-Grandvaux, M. and McGuffey, C. and Fedosejevs, R. and Vaisseau, X. and Tauschwitz, An. and Apiñaniz, J. I. and De Luis Blanco, D. and Gatti, G. and Huault, M. and Hernandez, J. A. Perez and Hu, S. X. and White, A. J. and Collins, L. A. and Nichols, K. and Neumayer, P. and Faussurier, G. and Vorberger, J. and Prestopino, G. and Verona, C. and Santos, J. J. and Batani, D. and Beg, F. N. and Roso, L. and Volpe, L.},
}
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