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This erratum1 is issued by the authors to note that the caption of Fig. 10 refers the reader to Table III in the published version of the manuscript, while the correct reference is to Table II.
PDF全文 Matter and Radiation at Extremes, 2020年第5卷第2期 pp.029901
The Editors of Matter and Radiation at Extremes (MRE) wish to express their deepest gratitude to the following individuals who generously provided advice on manuscripts as reviewers for MRE in the year of 2019 (names are listed in alphabetical order).
PDF全文 Matter and Radiation at Extremes, 2020年第5卷第2期 pp.023001
Fundamental Physics At Extremes
Properties of atoms and molecules undergo significant changes when subjected to spatial confinement. We study the excitation spectra of lithium-like atoms in the initial 1s22s electronic configuration when confined by an impenetrable spherical cavity. We implement Slater’s X-α method in Hartree–Fock theory to obtain the excitation spectrum. We verify that as the cavity size decreases, the total, 2s, 2p, and higher excited energy levels increase. Furthermore, we confirm the existence of crossing points between ns–np states for low values of the confinement radius such that the ns → np dipole transition becomes zero at that critical pressure. The crossing points of the s–p states imply that instead of photon absorption, one observes photon emission for cavities with radius smaller than the critical radius. Hence, the dipole oscillator strength associated with the 2s → 2p transition becomes negative, and for higher pressures, the 2s → 3p dipole oscillator strength transition becomes larger than unity. We validate the completeness of the spectrum by calculating the Thomas–Reiche–Kuhn sum rule, as well as the static dipole polarizability and mean excitation energy of lithium-like atoms. We find that the static dipole polarizability decreases and exhibits a sudden change at the critical pressure for the absorption-to-emission transition. The mean excitation energy increases as the pressure rises. However, as a consequence of the critical transition from absorption to emission, the mean excitation energy becomes undetermined for higher pressures, with implications for material damage under extreme conditions. For unconfined systems, our results show good to excellent agreement with data found in the literature.
PDF全文 Matter and Radiation at Extremes, 2020年第5卷第2期 pp.024401
K. A. Tanaka
K. M. Spohr
D. L. Balabanski
M. O. Cernaianu
D. G. Ghita
J. F. Ong
C. A. Ur
N. V. Zamfir
The emergence of a new era reaching beyond current state-of-the-art ultrashort and ultraintense laser technology has been enabled by the approval of around € 850 million worth of structural funds in 2011–2012 by the European Commission for the installation of Extreme Light Infrastructure (ELI). The ELI project consists of three pillars being built in the Czech Republic, Hungary, and Romania. This challenging proposal is based on recent technical progress allowing ultraintense laser fields in which intensities will soon be reaching as high as I0 ～ 1023 W cm?2. This tremendous technological advance has been brought about by the invention of chirped pulse amplification by Mourou and Strickland. Romania is hosting the ELI for Nuclear Physics (ELI-NP) pillar in M?gurele near Bucharest. The new facility, currently under construction, is intended to serve the broad national, European, and international scientific community. Its mission covers scientific research at the frontier of knowledge involving two domains. The first is laser-driven experiments related to NP, strong-field quantum electrodynamics, and associated vacuum effects. The second research domain is based on the establishment of a Compton-backscattering-based, high-brilliance, and intense γ beam with Eγ ? 19.5 MeV, which represents a merger between laser and accelerator technology. This system will allow the investigation of the nuclear structure of selected isotopes and nuclear reactions of relevance, for example, to astrophysics with hitherto unprecedented resolution and accuracy. In addition to fundamental themes, a large number of applications with significant societal impact will be developed. The implementation of the project started in January 2013 and is spearheaded by the ELI-NP/Horia Hulubei National Institute for Physics and Nuclear Engineering (IFIN-HH). Experiments will begin in early 2020.
PDF全文 Matter and Radiation at Extremes, 2020年第5卷第2期 pp.024402
High Pressure Physics and Materials Science
Recent reports of the superconductivity in hydrides of two different families (covalent lattice, as in SH3 and clathrate-type H-cages containing La and Y atoms, as in LaH10 and YH6) have revealed new families of high-Tc materials with Tc’s near room temperature values. These findings confirm earlier expectations that hydrides may have very high Tc’s due to the fact that light H atoms have very high vibrational frequencies, leading to high Tc values within the conventional Bardeen–Cooper–Schrieffer phonon mechanism of superconductivity. However, as is pointed out by Ashcroft, it is important to have the metallic hydrogen “alloyed” with the elements added to it. This concept of a metallic alloy containing a high concentration of metal-like hydrogen atoms has been instrumental in finding new high-Tc superhydrides. These new superhydride “room-temperature” superconductors are stabilized only at very high pressures above 100 GPa, making the experimental search for their superconducting properties very difficult. We will review the current experimental and theoretical results for LaH10?x and YH6?x superhydrides.
PDF全文 Matter and Radiation at Extremes, 2020年第5卷第2期 pp.028201
N. J. Hartley
L. G. Huang
Using the SG-III prototype laser at China Academy of Engineering Physics, Mianyang, we irradiated polystyrene (CH) samples with a thermal radiation drive, reaching conditions on the principal Hugoniot up to P ≈ 1 TPa (10 Mbar), and away from the Hugoniot up to P ≈ 300 GPa (3 Mbar). The response of each sample was measured with a velocity interferometry diagnostic to determine the material and shock velocity, and hence the conditions reached, and the reflectivity of the sample, from which changes in the conductivity can be inferred. By applying the self-impedance mismatch technique with the measured velocities, the pressure and density of thermodynamic points away from the principal Hugoniot were determined. Our results show an unexpectedly large reflectivity at the highest shock pressures, while the off-Hugoniot points agree with previous work suggesting that shock-compressed CH conductivity is primarily temperature-dependent.
PDF全文 Matter and Radiation at Extremes, 2020年第5卷第2期 pp.028401
Magnetic Driven Fusion
S. L. Jackson
A. V. Shishlov
V. A. Kokshenev
A. R. Beresnyak
R. K. Cherdizov
G. N. Dudkin
J. T. Engelbrecht
F. I. Fursov
N. E. Kurmaev
N. A. Ratakhin
V. A. Varlachev
Z-pinch experiments with a hybrid configuration of a deuterium gas puff have been carried out on the HAWK (NRL, Washington, DC) and GIT-12 (IHCE, Tomsk) pulsed power generators at 0.7 MA and 3 MA currents, respectively. On GIT-12, neutron yields reached an average value of 2 × 1012 neutrons, and deuterons were accelerated up to an energy of 30 MeV. This was 50 times the ion energy provided by the generator driving voltage of 0.6 MV and the highest energy observed in z-pinches and dense plasma foci. To confirm these unique results independently on another device, we performed several experimental campaigns on the HAWK generator. Comparison of the experiments on GIT-12 and HAWK helped us to understand which parameters are essential for optimized neutron production. Since the HAWK generator is of a similar pulsed power architecture as GIT-12, the experiments on GIT-12 and HAWK are important for the study of how charged-particle acceleration scales with the current.
PDF全文 Matter and Radiation at Extremes, 2020年第5卷第2期 pp.026401
N. R. Pereira
The first Dense Z-Pinch (DZP) conference, in 1984, marked an attempt to use then-modern pulsed power with a Z-pinch to work toward thermonuclear fusion energy. This 11th DZP conference in China is a good time to look back, to comment on progress since, and to project forward. What follows is a personal perspective: scattered comments from a sympathetic outsider and one-time participant. In these 35 years, Z-pinch theory has evolved from little more than cartoons to fully 3D MHD computer simulations, measurements have gone from mostly time- and spatially integrated diagnostics to monochromatic imaging, highly resolved x-ray spectroscopy, and active laser probing. Large pulsed power generators now drive x-ray-producing Z-pinches that are powerful enough for many applications; thermonuclear fusion may work single-shot in the future.
PDF全文 Matter and Radiation at Extremes, 2020年第5卷第2期 pp.026402