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Magnetic Driven Fusion|3 Article(s)
Challenges for plasma-facing components in nuclear fusion
Jochen Linke, Juan Du, Thorsten Loewenhoff, Gerald Pintsuk, Benjamin Spilker, Isabel Steudel, and Marius Wirtz
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. 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
- Publication Date: Jan. 01, 2019
- Vol. 4, Issue 5, 056201 (2019)
Experimental investigation of Z-pinch radiation source for indirect drive inertial confinement fusion
Zhenghong Li, Zhen Wang, Rongkun Xu, Jianlun Yang, Fan Ye, Yanyun Chu, Zeping Xu, Faxin Chen, Shijian Meng, Jianmin Qi, Qinyuan Hu, Yi Qin, Jiaming Ning, Zhanchang Huang, Linbo Li, and Shuqing Jiang
Z-pinch dynamic hohlraums (ZPDHs) could potentially be used to drive inertial confinement fusion targets. Double- or multishell capsules using the technique of volume ignition could exploit the advantages of ZPDHs while tolerating their radiation asymmetry, which would be unacceptable for a central ignition target. In this paper, we review research on Z-pinch implosions and ZPDHs for indirect drive targets at the Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics. The characteristics of double-shell targets and the associated technical requirements are analyzed through a one-dimensional computer code developed from MULTI-IFE. Some key issues regarding the establishment of suitable sources for dynamic hohlraums are introduced, such as soft X-ray power optimization, novel methods for plasma profile modulation, and the use of thin-shell liner implosions to inhibit the generation of prior-stagnated plasma. Finally, shock propagation and radiation characteristics in a ZPDH are presented and discussed, together with some plans for future work. Z-pinch dynamic hohlraums (ZPDHs) could potentially be used to drive inertial confinement fusion targets. Double- or multishell capsules using the technique of volume ignition could exploit the advantages of ZPDHs while tolerating their radiation asymmetry, which would be unacceptable for a central ignition target. In this paper, we review research on Z-pinch implosions and ZPDHs for indirect drive targets at the Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics. The characteristics of double-shell targets and the associated technical requirements are analyzed through a one-dimensional computer code developed from MULTI-IFE. Some key issues regarding the establishment of suitable sources for dynamic hohlraums are introduced, such as soft X-ray power optimization, novel methods for plasma profile modulation, and the use of thin-shell liner implosions to inhibit the generation of prior-stagnated plasma. Finally, shock propagation and radiation characteristics in a ZPDH are presented and discussed, together with some plans for future work.
Matter and Radiation at Extremes
- Publication Date: Jan. 01, 2019
- Vol. 4, Issue 4, 046201 (2019)
Researches on preconditioned wire array Z pinches in Xi’an Jiaotong University
Jian Wu, Yihan Lu, Fengju Sun, Xiaofeng Jiang, Zhiguo Wang, Daoyuan Zhang, Xingwen Li, and Aici Qiu
The dynamics of wire array Z pinches are greatly affected by the initial state of the wires, which can be preconditioned by a prepulse current. Recent advances in experimental research on preconditioned wire array Z pinches at Xi’an Jiaotong University are presented in this paper. Single-wire explosion experiments were carried out to check the state of the preconditioning and to obtain the current parameters needed for wire gasification. Double-wire explosion experiments were conducted to investigate the temporal evolution of the density distribution of the two gasified wires. Based on the results of these experiments, a double-pulse Z-pinch facility, Qin-1, in which a 10 kA prepulse current was coupled with the 0.8 MA main current was designed and constructed. Wire arrays of different wire materials, including silver and tungsten, can be preconditioned by the prepulse current to a gaseous state. Implosion of the two preconditioned aluminum wires exhibited no ablation and little trailing mass. The dynamics of wire array Z pinches are greatly affected by the initial state of the wires, which can be preconditioned by a prepulse current. Recent advances in experimental research on preconditioned wire array Z pinches at Xi’an Jiaotong University are presented in this paper. Single-wire explosion experiments were carried out to check the state of the preconditioning and to obtain the current parameters needed for wire gasification. Double-wire explosion experiments were conducted to investigate the temporal evolution of the density distribution of the two gasified wires. Based on the results of these experiments, a double-pulse Z-pinch facility, Qin-1, in which a 10 kA prepulse current was coupled with the 0.8 MA main current was designed and constructed. Wire arrays of different wire materials, including silver and tungsten, can be preconditioned by the prepulse current to a gaseous state. Implosion of the two preconditioned aluminum wires exhibited no ablation and little trailing mass.
Matter and Radiation at Extremes
- Publication Date: Jan. 01, 2019
- Vol. 4, Issue 3, 036201 (2019)
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