Journals >Matter and Radiation at Extremes
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2017
Volume: 2 Issue 5
5 Article(s)
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GUIDE for AUTHORS
GUIDE FOR AUTHORS
[in Chinese]
Matter and Radiation at Extremes
- Publication Date: Jan. 01, 1900
- Vol. 2, Issue 5, 275 (2017)
Review Article
Electron-positron pair production in ultrastrong laser fields
Bai Song Xie, Zi Liang Li, and Suo Tang
Electronepositron pair production due to the decay of vacuum in ultrastrong laser fields is an interesting topic which is revived recently because of the rapid development of current laser technology. The theoretical and numerical research progress of this challenging topic is reviewed. Many new findings are presented Electronepositron pair production due to the decay of vacuum in ultrastrong laser fields is an interesting topic which is revived recently because of the rapid development of current laser technology. The theoretical and numerical research progress of this challenging topic is reviewed. Many new findings are presented by different approaches such as the worldline instantons, the S-matrix theory, the kinetic method by solving the quantum Vlasov equation or/and the real-time Dirac-Heisenberg-Wigner formalism, the computational quantum field theory by solving the Dirac equation and so on. In particular, the effects of electric field polarizations on pair production are unveiled with different patterns of created momentum spectra. The effects of polarizations on the number density of created particles and the nonperturbative signatures of multiphoton process are also presented. The competitive interplay between the multiphoton process and nonperturbation process plays a key role in these new findings. These newly discovered phenomena are valuable to deepen the understanding of pair production in complex fields and even have an implication to the study of strong-field ionization. More recent studies on the pair production in complex fields as well as beyond laser fields are briefly presented in the view point of perspective future..
Matter and Radiation at Extremes
- Publication Date: Jan. 01, 1900
- Vol. 2, Issue 5, 225 (2017)
Laser performance upgrade for precise ICF experiment in SG-Ⅲ laser facility
Wanguo Zheng, Xiaofeng Wei, Qihua Zhu, Feng Jing, Dongxia Hu, Xiaodong Yuan, Wanjun Dai, Wei Zhou, Fang Wang, Dangpeng Xu, Xudong Xie, Bin Feng, Zhitao Peng, Liangfu Guo, Yuanbin Chen, Xiongjun Zhang, Lanqin Liu, Donghui Lin, Zhao Dang, Yong Xiang, Rui Zhang, Fang Wang, Huaiting Jia, and Xuewei Deng
The SG-Ⅲ laser facility (SG-Ⅲ) is the largest laser driver for inertial confinement fusion (ICF) researches in China, which has 48 beamlines and can deliver 180 kJ ultraviolet laser energy in 3 ns. In order to meet the requirements of precise physics experiments, some new functionalities need to be added to SG-Ⅲ and soThe SG-Ⅲ laser facility (SG-Ⅲ) is the largest laser driver for inertial confinement fusion (ICF) researches in China, which has 48 beamlines and can deliver 180 kJ ultraviolet laser energy in 3 ns. In order to meet the requirements of precise physics experiments, some new functionalities need to be added to SG-Ⅲ and some intrinsic laser performances need upgrade. So at the end of SG-Ⅲ's engineering construction, the 2-year laser performance upgrade project started. This paper will introduce the newly added functionalities and the latest laser performance of SG-Ⅲ. With these function extensions and performance upgrade, SG-Ⅲ is now fully prepared for precise ICF experiments and solidly paves the way towards fusion ignition..
Matter and Radiation at Extremes
- Publication Date: Jan. 01, 1900
- Vol. 2, Issue 5, 243 (2017)
Laser radiation pressure proton acceleration in gaseous target
V.K. Tripathi, Tung-Chang Liu, and Xi Shao
An analytical model for hole boring proton acceleration by a circularly-polarized CO2 laser pulse in a gas jet is developed. The plasma density profile near the density peak is taken to be rectangular, with inner region thickness l around a laser wavelength and density 10% above the critical, while the outside density An analytical model for hole boring proton acceleration by a circularly-polarized CO2 laser pulse in a gas jet is developed. The plasma density profile near the density peak is taken to be rectangular, with inner region thickness l around a laser wavelength and density 10% above the critical, while the outside density is 10% below the critical. On the rear side, plasma density falls off rapidly to a small value. The laser suffers strong reflection from the central region and, at normalized amplitude a0≥1, creates a double layer. The space charge field of the double layer, moving with velocity vfz^, reflects up-stream protons to 2vf velocity, incurring momentum loss at a rate comparable to radiation pressure. Reflection occurs for vf≤ωp (zflm/mp)-1/2 , where m and mp are the electron and proton masses, zf is the distance traveled by the compressed electron layer and ωp is the plasma frequency. For Gaussian temporal profile of the laser and parabolic density profile of the upstream plasma, the proton energy distribution is narrowly peaked..
Matter and Radiation at Extremes
- Publication Date: Jan. 01, 1900
- Vol. 2, Issue 5, 256 (2017)
Formation of Field Reversed Configuration (FRC) on the Yingguang-I device
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As a hybrid approach to realizing fusion energy, Magnetized Target Fusion (MTF) based on the Field Reversed Configuration (FRC), which has the plasma density and confinement time in the range between magnetic and inertial confinement fusion, has been recently widely pursued around the world. To investigate the formatioAs a hybrid approach to realizing fusion energy, Magnetized Target Fusion (MTF) based on the Field Reversed Configuration (FRC), which has the plasma density and confinement time in the range between magnetic and inertial confinement fusion, has been recently widely pursued around the world. To investigate the formation and confinement of the FRC plasma injector for MTF, the Yingguang-I, which is an FRC test device and contains a multi-bank program-discharged pulsed power sub-system, was constructed at the Institute of Fluid Physics (IFP), China. This paper presents the pulsed power components and their parameters of the device in detail, then gives a brief description of progress in experiments of FRC formation. Experimental results of the pulsed power sub-system show that the peak current/magnetic field of 110 kA/0.3 T, 10 kA/1.2 T and 1.7 MA/3.4 T were achieved in the bias, mirror and θ-pinch circuits with quarter cycle of 80 μs, 700 μs and 3.8 μs respectively. The induced electric field in the neutral gas was greater than 0.25 kV/cm when the ionization bank was charged to 70 kV. With H2 gas of 8 Pa, the plasma target of density 1016 cm-3, separatrix radius 4 cm, half-length 17 cm, equilibrium temperature 200 eV and lifetime 3 μs (approximately the half pulse width of the reversed field) have been obtained through the θ-pinch method when the bias, mirror, ionization and θ-pinch banks were charged to 5 kV, 5 kV, 55 kV and ±45 kV respectively. The images from the high-speed end-on framing camera demonstrate the formation processes of FRC and some features agree well with the results with the two-dimension magneto hydrodynamics code (2D-MHD)..
Matter and Radiation at Extremes
- Publication Date: Jan. 01, 1900
- Vol. 2, Issue 5, 263 (2017)
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