QUEST has a divertor configuration with a high and a negative n-index, and the problem of plasma vertical position instability control in QUEST is still under extensive study for achieving high efficiency plasma. The ...QUEST has a divertor configuration with a high and a negative n-index, and the problem of plasma vertical position instability control in QUEST is still under extensive study for achieving high efficiency plasma. The instability we considered is that the toroidal plasma moves either up or down in the vacuum chamber until it meets the vessel wall and is extinguished. The actively controlled coils （HCU and HCL） outside the vacuum vessel are serially connected in feedback with a measurement of the plasma vertical position to provide stabilizing control. In this work, a robust controller is employed by using the loop synthesis method, and provides robust stability over a wide range of n-index. Moreover, the gain of the robust controller is lower than that of a typical proportional derivative （PD） controller in the operational frequency range; it indicates that the robust controller needs less power consumption than the PD controller does.展开更多
Considering that tungsten(W)materials served as the plasma-facing material in the fusion reactor would be exposed to edge-localized modes(ELMs)-like thermal shock loading accompanied with He-ion irradiation,the W-TiC ...Considering that tungsten(W)materials served as the plasma-facing material in the fusion reactor would be exposed to edge-localized modes(ELMs)-like thermal shock loading accompanied with He-ion irradiation,the W-TiC composite produced with a wet-chemical method was conducted by the dual effects from the laser beam thermal shock first and He-ion irradia-tion later in this work.The microstructure changes of the W-TiC composite before and after two tests were characterized by scanning electron microscopy or transmission electron microscopy.After the laser beam thermal shock test,there was an obvious interface on the exposed surface of the W-TiC composite.Several main cracks and melting areas could be found nearby the interface and center,respectively.Furthermore,a mixture of tungsten oxide and TiC was easy to aggregate and form into circle areas surrounding the melting area.The thermal shock tested that W-TiC composite was then subjected to the He-ion irradiation.The typical features of fuzz structures could be detected on the surface of the W-TiC composite apart from the center of the melting area.Notably,several nano-sized He bubbles deeply distributed at grain boundaries in the melting area,owing to the grain boundary functioning as the free path for He diffusion.展开更多
文摘QUEST has a divertor configuration with a high and a negative n-index, and the problem of plasma vertical position instability control in QUEST is still under extensive study for achieving high efficiency plasma. The instability we considered is that the toroidal plasma moves either up or down in the vacuum chamber until it meets the vessel wall and is extinguished. The actively controlled coils （HCU and HCL） outside the vacuum vessel are serially connected in feedback with a measurement of the plasma vertical position to provide stabilizing control. In this work, a robust controller is employed by using the loop synthesis method, and provides robust stability over a wide range of n-index. Moreover, the gain of the robust controller is lower than that of a typical proportional derivative （PD） controller in the operational frequency range; it indicates that the robust controller needs less power consumption than the PD controller does.
基金the National Natural Science Foundation of China(Grant No.51574101)the Fundamental Research Funds for the Central Universities(Grant Nos.PA2018GDQT0010,PA2019GDZC0096,JZ2019HGTA0040)+2 种基金the Foundation of Laboratory of Nonferrous Metal Material and Processing Engineering of Anhui Province(15CZS08031)the Natural Science Foundation of Anhui Province(Grant Nos.201904b11020034,1908085ME115)the Foundation of Laboratory of Nonferrous Metal Material and Processing Engineering of Anhui Province,the Open Foundation of Key Laboratory of Advanced Functional Materials,Devices of Anhui Province and Double First Class enhancing independent innovation and social service capabilities of Hefei University of Technology(Grant No.45000-411104/011).
文摘Considering that tungsten(W)materials served as the plasma-facing material in the fusion reactor would be exposed to edge-localized modes(ELMs)-like thermal shock loading accompanied with He-ion irradiation,the W-TiC composite produced with a wet-chemical method was conducted by the dual effects from the laser beam thermal shock first and He-ion irradia-tion later in this work.The microstructure changes of the W-TiC composite before and after two tests were characterized by scanning electron microscopy or transmission electron microscopy.After the laser beam thermal shock test,there was an obvious interface on the exposed surface of the W-TiC composite.Several main cracks and melting areas could be found nearby the interface and center,respectively.Furthermore,a mixture of tungsten oxide and TiC was easy to aggregate and form into circle areas surrounding the melting area.The thermal shock tested that W-TiC composite was then subjected to the He-ion irradiation.The typical features of fuzz structures could be detected on the surface of the W-TiC composite apart from the center of the melting area.Notably,several nano-sized He bubbles deeply distributed at grain boundaries in the melting area,owing to the grain boundary functioning as the free path for He diffusion.
