Chen, G. L.
Lu, H. Y.
Wang, C.
Liu, J. S.
Li, R. X.
Ni, G. Q.
Xu, Z. Z.
We propose a plasma channel scheme to obtain an improved table-top laser driven fusion neutron yield as a result of explosions of large deuterium clusters irradiated by an intense laser pulse. A cylindrical plasma channel is created by two moderate intensity laser prepulses at the edge of a deuterium cluster jet along which an intense main laser pulse propagates several nanoseconds later. With the aid of this plasma channel, the main laser pulse will be allowed to deposit its energy into the central region of the deuterium gas jet where the cluster sizes are larger and the atomic density is higher. The plasma channel formation and its impact on the deuterium ion energy spectrum and the consequent fusion neutron yield have been investigated. The calculated results show that a remarkable increase of the table-top laser driven fusion neutron yield would be expected.
Drozdowski, W.
Wojtowicz, A.J.
Brylew, K.
?achmański, W.
Talik, E.
Szubka, M.
Kusz, J.
Guzik, A.
Balin, K.
Kisielewski, J.
?wirkowicz, M.
Paj?czkowska, A.
Drozdowski, W.
Wojtowicz, A. J.
Brylew, K.
Lachmanski, W.
Talik, E.
Szubka, M.
Kusz, J.
Guzik, A.
Balin, K.
Kisielewski, J.
Swirkowicz, M.
Pajaczkowska, A.
Interior of Czochralski-grown (Lu,Y)AG:Pr crystals has been examined by means of several techniques, such as X-Ray Photoelectron Spectroscopy, X-Ray Diffraction, Time-of-Flight Secondary Ion Mass Spectrometry, and magnetic susceptibility measurements. Additionally, their luminescence has been monitored at various combinations of a double-beam (X-ray/IR) excitation.
A version of the \({{\fancyscript{H}}} \)-LU factorization is introduced, based on the individual computational tasks occurring during the block-wise \({{\fancyscript{H}}} \)-LU factorization. The dependencies between these tasks form a directed acylic graph, which is used for efficient scheduling on parallel systems. The algorithm is especially suited for many-core processors and shows a much improved parallel scaling behavior compared to previous \({{\fancyscript{H}}} \)-LU factorization algorithms.
The rhodium-rich germanides RERh4Ge2 (RE = Y, Gd–Lu) were synthesized by arc-melting of the elements and subsequent annealing in a muffle furnace. The samples were characterized through Guinier powder patterns. The structures of YRh4Ge2 and TmRh4Ge2 were refined from X-ray single crystal diffractometer data: new type, Pnma, Z = 4, a = 1136.4(2) pm, b = 418.29(5) pm, c = 910.12(9) pm, wR2 = 0.0268, 707 F 2 values for YRh4Ge2 and a = 1131.5(1) pm, b = 416.54(5) pm, c = 908.06(9) pm, wR2 = 0.0276, 719 F 2 values for TmRh4Ge2 with 44 variables per refinement. The two crystallographically independent germanium sites both show distorted trigonal prismatic coordination by four rhodium and two rare earth atoms. The basic structural motifs are double prisms, similar to the structures of ZrFe4Si2 and CeIn4Au2. The shortest interatomic distances are observed for the Rh–Ge contacts within the three-dimensional [Rh4Ge2] polyanionic network which are further stabilized through weak Rh–Rh interactions. The calculations of the electronic structure within DFT done exemplarily for the yttrium compound show an itinerant like weak metal with a low density of states at the Fermi level and intricate chemical bonding due to the presence of two germanium sites interacting with the four rhodium sites.
Zhou, M. L.
Liu, B.
Hu, R. H.
Shou, Y. R.
Lin, C.
Lu, H. Y.
Lu, Y. R.
Gu, Y. Q.
Ma, W. J.
Yan, X. Q.
In the case of a thin plasma slab accelerated by the radiation pressure of an ultra-intense laser pulse, the development of Rayleigh-Taylor instability ( RTI) will destroy the acceleration structure and terminate the acceleration process much sooner than theoretical limit. In this paper, a new scheme using multiple Gaussian pulses for ion acceleration in a radiation pressure acceleration regime is investigated with particle-in-cell simulation. We found that with multiple Gaussian pulses, the instability could be efficiently suppressed and the divergence of the ion bunch is greatly reduced, resulting in a longer acceleration time and much more collimated ion bunch with higher energy than using a single Gaussian pulse. An analytical model is developed to describe the suppression of RTI at the laser-plasma interface. The model shows that the suppression of RTI is due to the introduction of the long wavelength mode RTI by the multiple Gaussian pulses. Published by AIP Publishing.
Ugendar, Kodam
Kumar, Hanuma
Markaneyulu, G.
Rani, G. Neeraja
The dielectric and impedance spectroscopic properties of NiFe1.95R0.05O4 (R =3D Y, Yb and Lu) were investigated. The materials were prepared by solid state reaction and crystallized in the cubic inverse spinel phase with a very small amount additional phase of RFeO3 (R =3D Y, Yb and Lu) as secondary phase. The scanning electron micrograph images clearly show grains (similar to 2 mu m) which are separated by thin grain boundaries. The presences of all elements were confirmed by the energy dispersive X-ray elemental mapping. The frequency variation of epsilon' shows the dispersion, following the Koop's phenomenological theory, which considers the dielectric structure as an inhomogeneous medium of two-layers of the Maxwell-Wagner type. Impedance spectroscopic analysis indicates the different relaxation mechanisms, which corresponds to bulk grain and grain-boundaries. Their contributions to the electrical conductivity and capacitance of these materials were discussed in detailed.
Dzevenko, M.
Bigun, I.
Pustovoychenko, M.
Havela, L.
Kalychak, Ya.
New ternary indides RE 8CoIn 3 (RE = Y, Dy-Tm, Lu) have been prepared by arc-melting and subsequent annealing at T = 870 K. The crystal structures have been studied using X-ray powder diffraction. The RE 8CoIn 3 indides are isotypic with Pr 8CoGa 3, space group P63mc, Pearson code hP24: a = 10.3678(2), c = 7.0069(2) Aring for Y8CoIn3; a = 10.3370(4), c = 6.9246(3) Aring for Dy 8CoIn 3; a = 10.2856(2), c = 6.9030(2) Aring for Ho 8CoIn 3; a = 10.2374(2), c = 6.8759(2) Aring for Er 8CoIn 3; a = 10.1863(2), c = 6.8461(2) Aring for Tm 8CoIn 3; a = 10.1168(4), c = 6.7977(4) Aring for Lu 8CoIn 3. The coordination polyhedra of the RE atoms have 12-, 13- and 14-vertices. The polyhedron around the Co atom is an octahedron with one additional atom, and around the In atoms it is a strongly distorted trigonal prism with five additional atoms. [All rights reserved Elsevier].
Two different charge carrier trapping processes have been investigated in RE2O2S:Ln(3+) (RE =3D La, Gd, Y, and Lu; Ln =3D Ce, Pr, and Tb) and RE2O2S:M (M =3D Ti4+ and Eu3+). Cerium, praseodymium and terbium act as recombination centers and hole trapping centers while host intrinsic defects provide the electron trap. The captured electrons released from the intrinsic defects recombine at Ce4+, Pr4+, or Tb4+ via the conduction band. On the other hand, Ti4+ and Eu3+ act as recombination centers and electron trapping centers while host intrinsic defects act as hole trapping centers. For these codopants we find evidence that recombination is by means of hole release instead of electron release. The released holes recombine with the trapped electrons on Ti3+ or Eu2+ and yield broad Ti4+ yellow-red charge transfer (CT) emission or characteristic Eu3+ 4f-4f emission. We will conclude that the afterglow in Y2O2S:Ti4+, Eu3+ is due to hole release instead of more common electron release.