Matter and Radiation at Extremes
Search

2019, 4(5) Column

MORE

Matter and Radiation at Extremes 第4卷 第5期

Author Affiliations
Abstract
1 State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing 100871, People’s Republic of China
2 CAPT, HEDPS and IFSA Collaborative Innovation Center of MoE, College of Engineering, Peking University, Beijing 100871, People’s Republic of China
3 School of Advanced Materials, Shenzhen Graduate School, Peking University, Shenzhen 518055, People’s Republic of China
4 New Energy Research Institute, School of Environment and Energy, South China University of Technology, Guangzhou 510006, People’s Republic of China
We present a simple and reliable method, based on the over-barrier model and Lindhard’s formula, to calculate the energy loss, charge transfer, and normalized intensity of highly charged ions penetrating through 2D ultrathin materials, including graphene and carbon nanomembranes. According to our results, the interaction between the ions and the 2D material can be simplified as an equivalent two-body collision, and we find that full consideration of the charge exchange effect is key to understanding the mechanism of ion energy deposition in an ultrathin target. Not only can this semiclassical model be used to evaluate the ion irradiation effect to a very good level of accuracy, but it also provides important guidance for tailoring the properties of 2D materials using ion beams.
Matter and Radiation at Extremes
2019, 4(5): 054401
Author Affiliations
Abstract
1 ELI-NP, “Horia Hulubei” National Institute for Physics and Nuclear Engineering, 30 Reactorului Street, RO-077125 Bucharest-Magurele, Romania
2 Institute of Applied Physics, 46 Ulyanov Street, 603950 Nizhny Novgorod, Russia
3 Université Bordeaux, CNRS, CEA, CELIA, UMR 5107, F-33405 Talence, France
4 School of Physics and Astronomy, Tel-Aviv University, Tel-Aviv 69978, Israel
5 LULI–CNRS, Ecole Polytechnique, CEA; Université Paris-Saclay; UPMC Université Paris 06; Sorbonne Université, F-91128 Palaiseau cedex, France
With the much-anticipated multi-petawatt (PW) laser facilities that are coming online, neutron sources with extreme fluxes could soon be in reach. Such sources would rely on spallation by protons accelerated by the high-intensity lasers. These high neutron fluxes would make possible not only direct measurements of neutron capture and β-decay rates related to the r-process of nucleosynthesis of heavy elements, but also such nuclear measurements in a hot plasma environment, which would be beneficial for s-process investigations in astrophysically relevant conditions. This could, in turn, finally allow possible reconciliation of the observed element abundances in stars and those derived from simulations, which at present show large discrepancies. Here, we review a possible pathway to reach unprecedented neutron fluxes using multi-PW lasers, as well as strategies to perform measurements to investigate the r- and s-processes of nucleosynthesis of heavy elements in cold matter, as well as in a hot plasma environment.
Matter and Radiation at Extremes
2019, 4(5): 054402
Author Affiliations
Abstract
1 Joint Institute for High Temperatures of the Russian Academy of Sciences, Izhorskaya 13 Bldg 2, Moscow 125412, Russia
2 Moscow Institute of Physics and Technology, Institutskiy Pereulok 9, Dolgoprudny, Moscow Region 141701, Russia
Calculations of thermodynamic and radiative characteristics of hot dense plasmas within different quantum-statistical approaches, such as the use of the Hartree–Fock–Slater model and the ion model, are presented. Calculated equations of state of different substances are used to investigate findings from absolute and relative measurements of the compressibility of solid aluminum samples in strong shock waves. It is shown that our calculated Hugoniot adiabat of aluminum is in a good agreement with experimental data and other theoretical results from first principles. We also present a review of the most important applications of the quantum-statistical approach to the study of radiative properties of hot dense plasmas. It includes the optimization problem of hohlraum wall materials for laser inertial fusion, calculations of the radiative efficiency of complex materials for optically thin plasma in X-pinch, modeling of radiative and gas-dynamic processes in plasma for experiments, where both intense laser and heavy ion beams are used, and temperature diagnostics for X- and Z-pinch plasmas.
Matter and Radiation at Extremes
2019, 4(5): 054403
Author Affiliations
Abstract
1 Laser Fusion Research Center, China Academy of Engineering Physics, Mianyang 621900, China
2 Tsinghua University, Beijing 100084, China
3 Institute of Applied Physics and Computational Mathematics, Beijing 100088, China
Optical Thomson scattering (OTS) diagnostics have been continuously developed on a series of large laser facilities for inertial confinement fusion (ICF) research in China. We review recent progress in the use of OTS diagnostics to study the internal plasma conditions of ICF gas-filled hohlraums. We establish the predictive capability for experiments by calculating the time-resolved Thomson scattering spectra based on the 2D radiation-hydrodynamic code LARED, and we explore the fitting method for the measured spectra. A typical experiment with a simplified cylindrical hohlraum is conducted on a 10 kJ-level laser facility, and the plasma evolution around the laser entrance hole is analyzed. The dynamic effects of the blast wave from the covering membrane and the convergence of shocks on the hohlraum axis are observed, and the experimental results agree well with those of simulations. Another typical experiment with an octahedral spherical hohlraum is conducted on a 100 kJ-level laser facility, and the plasma evolution at the hohlraum center is analyzed. A discrepancy appears between experiment and simulation as the electron temperature rises, indicating the occurrence of nonlocal thermal conduction.
Matter and Radiation at Extremes
2019, 4(5): 055201
Author Affiliations
Abstract
1 Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang, Sichuan 621900, People’s Republic of China
2 Institute of Applied Physics and Computational Mathematics, Beijing 100088, People’s Republic of China
3 CAS Key Laboratory of Geospace Environment and Department of Engineering and Department of Engineering and Applied Physics, University of Science and Technology of China, Hefei, Anhui 230027, People’s Republic of China
We report experimental research on laser plasma interaction (LPI) conducted in Shenguang laser facilities during the past ten years. The research generally consists of three phases: (1) developing platforms for LPI research in mm-scale plasma with limited drive energy, where both gasbag and gas-filled hohlraum targets are tested; (2) studying the effects of beam-smoothing techniques, such as continuous phase plate and polarization smoothing, on the suppression of LPI; and (3) exploring the factors affecting LPI in integrated implosion experiments, which include the laser intensity, gas-fill pressure, size of the laser-entrance hole, and interplay between different beam cones. Results obtained in each phase will be presented and discussed in detail.
Matter and Radiation at Extremes
2019, 4(5): 055202
Author Affiliations
Abstract
1 Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
2 Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
3 Dipartimento SBAI, Università degli Studi di Roma “La Sapienza,” Via Antonio Scarpa 14, 00161, Roma, Italy
The impact of fuel-ion diffusion in inertial confinement fusion implosions is assessed using nuclear reaction yield ratios and reaction histories. In T3He-gas-filled (with trace D) shock-driven implosions, the observed TT/T3He yield ratio is ~2× lower than expected from temperature scaling. In D3He-gas-filled (with trace T) shock-driven implosions, the timing of the D3He reaction history is ~50 ps earlier than those of the DT reaction histories, and average-ion hydrodynamic simulations cannot reconcile this timing difference. Both experimental observations are consistent with reduced T ions in the burn region as predicted by multi-ion diffusion theory and particle-in-cell simulations.
Matter and Radiation at Extremes
2019, 4(5): 055401
Author Affiliations
Abstract
1 E.T.S.I. Aeronáutica y del Espacio, Universidad Politécnica de Madrid, P. Cardenal Cisneros 3, E-28040, Madrid, Spain
2 CEA, DAM, DIF, 91297 Arpajon Cedex, France
3 Centre de Mathématiques et de Leurs Applications, ENS Cachan and CNRS, 61 Av. du President Wilson, 94235 Cachan Cedex, France
4 AWE plc, Aldermaston, Reading, Berkshire RG7 4PR, United Kingdom
Three-dimensional (3D) hydrodynamic numerical simulations of laser driven thin-shell gas-filled microballoons have been carried out using the computer code MULTI-3D [Ramis et al., Phys. Plasmas 21, 082710 (2014)]. The studied configuration corresponds to experiments carried at the ORION laser facility [Hopps et al., Plasma Phys. Controlled Fusion 57, 064002 (2015)]. The MULTI-3D code solves single-temperature hydrodynamics, electron heat transport, and 3D ray tracing with inverse bremsstrahlung absorption on unstructured Lagrangian grids. Special emphasis has been placed on the genuine 3D effects that are inaccessible to calculations using simplified 1D or 2D geometries. These include the consequences of (i) a finite number of laser beams (10 in the experimental campaign), (ii) intensity irregularities in the beam cross-sectional profiles, (iii) laser beam misalignments, and (iv) power imbalance between beams. The consequences of these imperfections have been quantified by post-processing the numerical results in terms of capsule nonuniformities (synthetic emission and absorption images) and implosion efficiency (convergence ratio and neutron yield). Statistical analysis of these outcomes allows determination of the laser tolerances that guarantee a given level of target performance.
Matter and Radiation at Extremes
2019, 4(5): 055402
Author Affiliations
Abstract
1 GSI Helmholtzzentrum für Schwerionenforschung, Planckstrasse 1, 64291 Darmstadt, Germany
2 School of Science, Xi’An Jiaotong University, Xianning West Road 28, Xi’An 7100049, China
3 National Research Nuclear University MEPhI, Moscow, Russia
A number of heavy-ion accelerators are either under construction (e.g., the Facility for Antiproton and Ion Research in Darmstadt and the High Intensity Accelerator Facility in China) or already in operation at many places worldwide. For these accelerators, activation of construction components due to beam loss, even during routine machine operation, is a serious issue, especially with the upcoming high-intensity facilities. Aluminum is one of the most commonly used construction materials in beam lines, collimators, and other components. Therefore, we report here on activation experiments on aluminum samples to verify and benchmark simulation codes. The analysis was performed by gamma spectroscopy of the irradiated targets. Our results on the induced activity measured in samples irradiated by uranium beams at 125 MeV/u and 200 MeV/u and a xenon beam at 300 MeV/u show activation levels significantly lower than those predicted by FLUKA simulations.
Matter and Radiation at Extremes
2019, 4(5): 055403
Author Affiliations
Abstract
Forschungszentrum Jülich GmbH, Institut für Energie und Klimaforschung, 52425 Jülich, Germany
The interaction processes between the burning plasma and the first wall in a fusion reactor are diverse: the first wall will be exposed to extreme thermal loads of up to several tens of megawatts per square meter during quasistationary operation, combined with repeated intense thermal shocks (with energy densities of up to several megajoules per square meter and pulse durations on a millisecond time scale). In addition to these thermal loads, the wall will be subjected to bombardment by plasma ions and neutral particles (D, T, and He) and by energetic neutrons with energies up to 14 MeV. Hopefully, ITER will not only demonstrate that thermonuclear fusion of deuterium and tritium is feasible in magnetic confinement regimes; it will also act as a first test device for plasma-facing materials (PFMs) and plasma-facing components (PFCs) under realistic synergistic loading scenarios that cover all the above-mentioned load types. In the absence of an integrated test device, material tests are being performed primarily in specialized facilities that concentrate only on the most essential material properties. New multipurpose test facilities are now available that can also focus on more complex loading scenarios and thus help to minimize the risk of an unexpected material or component failure. Thermonuclear fusion—both with magnetic and with inertial confinement—is making great progress, and the goal of scientific break-even will be reached soon. However, to achieve that end, significant technical problems, particularly in the field of high-temperature and radiation-resistant materials, must be solved. With ITER, the first nuclear reactor that burns a deuterium–tritium plasma with a fusion power gain Q ≥ 10 will start operation in the next decade. To guarantee safe operation of this rather sophisticated fusion device, new PFMs and PFCs that are qualified to withstand the harsh environments in such a tokamak reactor have been developed and are now entering the manufacturing stage.
Matter and Radiation at Extremes
2019, 4(5): 056201

动态信息

MORE
动态信息 丨 2019-12-16
年终大喜:MRE被SCI正式收录!
动态信息 丨 2018-09-12
MRE被ESCI收录