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大螺旋装置中中性束注入加热的长脉冲放电的等离子体特征
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作者 Takei.,Y 旭日 《国外核聚变》 2000年第6期35-43,共9页
在大螺旋装置(LHD)中已实现了长脉冲中性束注入加热,在长脉冲等离子体的不同平均密度下观察到两种不同的约束状态,在0.6MW的注入功率下准稳态等离子体持续了2ls,其中中心等离子体温度约为1keV,线平均电子密度为0.3×10∧19m∧... 在大螺旋装置(LHD)中已实现了长脉冲中性束注入加热,在长脉冲等离子体的不同平均密度下观察到两种不同的约束状态,在0.6MW的注入功率下准稳态等离子体持续了2ls,其中中心等离子体温度约为1keV,线平均电子密度为0.3×10∧19m∧-3,放电持续时间如此延长, 但仍能维持短脉冲放电的等离子体性能。能量约束时间几乎与短脉冲放电的 能量约束时间相同,它是国际仿星器定标ISS95的1.3倍,在较高密度情况下观察到张弛振荡现象,仿佛等离子体会呼吸似的,此振荡持续20s,其周期为1-2s。这种现象的特征是电子温度的分布扩展和收缩。密度振荡与温度振荡异相,并且与密度钳制现象有关,本文详细说明在呼吸振荡现象下所观察到的等离子体性能。根据最后闭合磁面附近的屏蔽效应以及加热功率和辐射功率之间的功率平衡,也讨论了呼吸振荡的可能机理,长脉冲加热结果表明LHD的独有特征,在LHD上由于无破裂和不需要电流驱动,所以不需要特殊的反馈致稳。 展开更多
关键词 中性束注入 大螺旋装置 长脉冲放电 张弛振荡现象 等离子特征 托卡马克装置
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Relaxation oscillations induced by an order gap between exciting frequency and natural frequency 被引量:5
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作者 CHEN XiaoKe LI ShaoLong +1 位作者 ZHANG ZhengDi BI QinSheng 《Science China(Technological Sciences)》 SCIE EI CAS CSCD 2017年第2期289-298,共10页
The main purpose of the paper is to display the relaxation oscillations, known as the bursting phenomena, for the coupled oscillators with periodic excitation with an order gap between the exciting frequency and the n... The main purpose of the paper is to display the relaxation oscillations, known as the bursting phenomena, for the coupled oscillators with periodic excitation with an order gap between the exciting frequency and the natural frequency. For the case when the exciting frequency is much smaller than the natural frequency, different types of bursting oscillations such as fold/fold, Hopf/Hopf bursting oscillations can be observed. By regarding the whole exciting term as a slow-varying parameter on the fact that the exciting term changes on a much smaller time scale, bifurcations sets of the generalized autonomous system is derived, which divide the parameter space into several regions associated with different types of dynamical behaviors. Two cases with typical bifurcation patterns are focused on as examples to explore the dynamical evolution with the variation of the amplitude of the external excitation. Bursting oscillations which alternate between quiescent states (QSs) and repetitive spiking states (SPs) can be obtained, the mechanism of which is presented by introducing the transformed phase portraits overlapping with the bifurcation diagrams of the generalized autonomous system. It is found that not only the forms of QSs and SPs, but also the bifurcations at the transition points between QSs and SPs, may influence the structures of bursting attractors. Furthermore, the amplitudes and the frequencies related to SPs may depend on the bifurcation patterns from the quiescent sates. 展开更多
关键词 coupled oscillators periodic excitation bursting oscillations bifurcation mechanism
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