Journals >Matter and Radiation at Extremes
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2019
Volume: 4 Issue 1
6 Article(s)
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Editorial
Progress and prospect
Weiyan Zhang, and E. M. Campbell
Matter and Radiation at Extremes
- Publication Date: Mar. 25, 2019
- Vol. 4, Issue 1, 013001 (2019)
Fundamental Physics at Extremes
Collimated GeV attosecond electron–positron bunches from a plasma channel driven by 10 PW lasers
Xing-Long Zhu, Min Chen, Tong-Pu Yu, Su-Ming Weng, Feng He, and Zheng-Ming Sheng
High-energy positrons and bright γ-ray sources are of great importance both in fundamental research and for practical applications. However, collimated GeV electron–positron pair jets and γ-ray flashes are still rarely produced in the laboratory. Here, we demonstrate that by irradiating a near-critical-density plasma cHigh-energy positrons and bright γ-ray sources are of great importance both in fundamental research and for practical applications. However, collimated GeV electron–positron pair jets and γ-ray flashes are still rarely produced in the laboratory. Here, we demonstrate that by irradiating a near-critical-density plasma channel with two 10 PW-scale laser pulses, highly directional GeV electron–positron pairs and bright γ-ray beams can be efficiently generated. Three-dimensional particle-in-cell simulations show the formation of GeV positron jets with high density (
Matter and Radiation at Extremes
- Publication Date: Mar. 25, 2019
- Vol. 4, Issue 1, 014401 (2019)
High Pressure Physics and Materials Science
Progress and challenges in the fabrication of DPS shells for ICF
Meifang Liu, Yawen Huang, Sufen Chen, Dawei Pan, Miao Chen, Qiaomei Chu, Yiyang Liu, Qiang Yin, and Zhanwen Zhang
To improve the quality of deuterated polystyrene (DPS) shells, the synthesis and purification of DPS as well as the fabrication of DPS shells are investigated. The molecular weight and molecular weight distribution, measured by GPC-MALLS, are about 350 kg mol-1 and less than 2.0, respectively. The results of TG and GC-To improve the quality of deuterated polystyrene (DPS) shells, the synthesis and purification of DPS as well as the fabrication of DPS shells are investigated. The molecular weight and molecular weight distribution, measured by GPC-MALLS, are about 350 kg mol-1 and less than 2.0, respectively. The results of TG and GC-MS indicate that the residual solvent is almost completely removed. DPS shells with ～ 300 μm –2500 μm diameter and ～10 μm–100 μm wall thickness are successfully prepared by a microfluidic device. The monodispersity of the diameter is much better than that of the wall thickness in a batch of DPS shells. The vacuoles can be suppressed by both reducing hydrophilic residues in DPS and adding some salts into the outer water phase (W2). The defects appearing during the drying process decrease by heat treatment, ethanol exchange, and lowered drying temperature. The results presented in this work not only provide guidelines for the preparation of DPS shells of better quality, but also indicate challenges for the future..
Matter and Radiation at Extremes
- Publication Date: Nov. 14, 2019
- Vol. 4, Issue 1, 018401 (2019)
Laser and Particle Beam Fusion
Characterization of supersonic and subsonic gas targets for laser wakefield electron acceleration experiments
S. Lorenz, G. Grittani, E. Chacon-Golcher, C. M. Lazzarini, J. Limpouch, F. Nawaz, M. Nevrkla, L. Vilanova, and T. Levato
The choice of the correct density profile is crucial in laser wakefield acceleration. In this work, both subsonic and supersonic gas targets are characterized by means of fluid-dynamic simulations and experimental interferometric measurements. The gas targets are studied in different configurations, and the density proThe choice of the correct density profile is crucial in laser wakefield acceleration. In this work, both subsonic and supersonic gas targets are characterized by means of fluid-dynamic simulations and experimental interferometric measurements. The gas targets are studied in different configurations, and the density profiles most suitable for laser wakefield acceleration are discussed..
Matter and Radiation at Extremes
- Publication Date: Mar. 20, 2019
- Vol. 4, Issue 1, 015401 (2019)
Pulsed Power Technology and High Power Electromagnetics
Research at Tsinghua University on electrical explosions of wires
Xinxin Wang
Electrical explosion of a wire (EEW) has been investigated for more than ten years at Tsinghua University, and the main results are reviewed in this paper. Based on EEW in vacuum, an X-pinch was used as an x-ray source for phase-contrast imaging of small insects such as mosquitoes and ants in which it was possible to oElectrical explosion of a wire (EEW) has been investigated for more than ten years at Tsinghua University, and the main results are reviewed in this paper. Based on EEW in vacuum, an X-pinch was used as an x-ray source for phase-contrast imaging of small insects such as mosquitoes and ants in which it was possible to observe clearly their detailed internal structures, which can never be seen with conventional x-ray radiography. Electrical explosion of a wire array (EEWA) in vacuum is the initial stage in the formation of a wire-array Z-pinch. The evolution of EEWA was observed with x-ray backlighting using two X-pinches as x-ray sources. It was found that each wire in an EEWA exhibits a core–corona structure instead of forming a fully vaporized metallic vapor. This structure is detrimental to the plasma implosion of a Z-pinch. By inserting an insulator as a flashover switch into the cathode, formation of a core–corona structure was suppressed and core-free EEWA was realized. EEW in gases was used for nanopowder production. Three parameters (vaporization rate, gas pressure, and energy deposited in the exploding plasma) were found to influence the nanoparticle size. EEW in water was used for shock-wave generation. The shock wave generated by melting could be recorded with a piezoelectric gauge only in underheat EEW. For EEW with a given stored energy but different energy-storage capacitor banks, the small capacitor bank produced a rapidly rising current that deposited more energy into the wire and generated a stronger shock wave..
Matter and Radiation at Extremes
- Publication Date: Nov. 14, 2019
- Vol. 4, Issue 1, 017201 (2019)
Investigation of wire-array Z-pinches by laser probing diagnostics
V. V. Ivanov, A. A. Anderson, and D. Papp
Laser diagnostics provides powerful tools for the investigation of dense Z-pinches. In this paper, wire-array Z-pinches are investigated at the 1 MA Zebra generator using laser diagnostics at different wavelengths coupled with x-ray diagnostics. Plasma dynamics during the ablation, implosion, and stagnation stages are Laser diagnostics provides powerful tools for the investigation of dense Z-pinches. In this paper, wire-array Z-pinches are investigated at the 1 MA Zebra generator using laser diagnostics at different wavelengths coupled with x-ray diagnostics. Plasma dynamics during the ablation, implosion, and stagnation stages are observed by multiframe diagnostics. Cascading and nonprecursor implosions are studied in wire arrays. Ultraviolet diagnostics allows deep penetration into the Z-pinch plasma at stagnation. End-on probing reveals the complicated structure of the precursor. Strong magnetohydrodynamic instabilities are found in a dense pinch hidden in the trailing plasma. Small-scale instabilities are seen in the Z-pinch plasma with micrometer resolution. Probing of the pinch from four directions shows asymmetrical trailing plasma in some configurations of wire arrays. Faraday rotation diagnostics reveals the magnetic fields and the current distribution in the plasma of the precursor and Z-pinch. Redistribution of current in the trailing plasma is seen during kink and sausage instabilities in the stagnation stage. The formation of micropinches and hot spots in the Z-pinch is analyzed with coupled laser and x-ray diagnostics. Different laser diagnostics allow the study of Z-pinch plasmas in all stages, including fast dynamics and instabilities..
Matter and Radiation at Extremes
- Publication Date: Mar. 25, 2019
- Vol. 4, Issue 1, 017401 (2019)
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