We report and discuss the results of x-ray radiation measurements in the Sino-Russian joint Z-Pinch experiments on Angara-5-1 facility with a load current of 2.5-3.6MA. The measurements were conducted by using an x-ra...We report and discuss the results of x-ray radiation measurements in the Sino-Russian joint Z-Pinch experiments on Angara-5-1 facility with a load current of 2.5-3.6MA. The measurements were conducted by using an x-ray power meter (XRPM) and a time-resolved one-dimensional x-ray imaging system developed in China Academy of Engineering Physics. The experimental results indicate that an x-ray power-platform prior to a main peak and a less intensive sub-peak after the main peak in the waveform exist for the nested-wire array implosions, and the radiation process is relatively faster than that in the case of the single array. Laser shadowgraph of the imploding plasma suggests that the prior power-platform is a result of the collision of the inner-outer plasma layers. The faster radiation process of nested array implosion can be explained by analysing the corresponding result of the time-resolved one-dimensional imaging system, which demonstrates a better axial imploding uniformity and synchronization. In comparison with x-ray diode, the XRPM yields a higher height of x-ray power-platform due to its fiat energy response. The sub-peak after the main peak is proposed to be a result of the later-time additional implosion of plasma.展开更多
We present a method,which combines the Gaussian decomposition method and the "distributed-lens" method,for analysing Z-scan curves of cascading nonlinear medium layers or a complicated cascading structure.A ...We present a method,which combines the Gaussian decomposition method and the "distributed-lens" method,for analysing Z-scan curves of cascading nonlinear medium layers or a complicated cascading structure.A good agreement with the experimental data is obtained.The method would be useful to design optical limiters and to determine the nonlinearities of cascading medium layers.展开更多
The experimental system for electrically exploding single metal wire has been designed and manufactured. Expansion of the dense plasma column formed from an electrically exploding Cu wire of diameter 30/~m has been s...The experimental system for electrically exploding single metal wire has been designed and manufactured. Expansion of the dense plasma column formed from an electrically exploding Cu wire of diameter 30/~m has been studied with a high-speed photographer to obtain the time-dependent radius (R-t) curve. The experimental results demonstrate that the mean ex-pansion rate of the dense plasma column is 1.94μm/ns, 2.6μm/ns and 3.75μm/ns according to the peak pulse current 4.5 kA, 7 kA and 9.5 kA respectively. The results can be beneficial to giving a profound understanding of the early stage of wire-array Z-pinch physics and to improvement on their design.展开更多
A hybrid model of MHD and kinetic theory is proposed to investigate the synergetic stabilizing effects of sheared axial flow and finite Larmor radius on the RayleighTaylor instability in Zpinch implosions.In our m...A hybrid model of MHD and kinetic theory is proposed to investigate the synergetic stabilizing effects of sheared axial flow and finite Larmor radius on the RayleighTaylor instability in Zpinch implosions.In our model the MHD plasma is considered to respond to a perturbation with exp at frequency ω+ik2⊥ρ2iΩi instead of frequency ω,where k2⊥ρ2i is the finite Larmor radius effects given from the general kinetic theory of magnetized plasma.Therefore linearized continuity and momentum equations include automatically the finite Larmor radius effects.Dispersion relation is derived,which includes the effects of a density discontinuity and the finite Larmor radius as well as a sheared flow that produces the KelvinHelmholtz instability.The dispersion equation is examined in three cases.The results indicate that the synergetic effect of sheared axial flow and the finite Larmor radius can mitigate both the RayleighTaylor instability and the hybrid RayleighTaylor/KelvinHelmholtz instability.Moreover,the synergetic mitigation effect is stronger than either of them acting separately.展开更多
文摘We report and discuss the results of x-ray radiation measurements in the Sino-Russian joint Z-Pinch experiments on Angara-5-1 facility with a load current of 2.5-3.6MA. The measurements were conducted by using an x-ray power meter (XRPM) and a time-resolved one-dimensional x-ray imaging system developed in China Academy of Engineering Physics. The experimental results indicate that an x-ray power-platform prior to a main peak and a less intensive sub-peak after the main peak in the waveform exist for the nested-wire array implosions, and the radiation process is relatively faster than that in the case of the single array. Laser shadowgraph of the imploding plasma suggests that the prior power-platform is a result of the collision of the inner-outer plasma layers. The faster radiation process of nested array implosion can be explained by analysing the corresponding result of the time-resolved one-dimensional imaging system, which demonstrates a better axial imploding uniformity and synchronization. In comparison with x-ray diode, the XRPM yields a higher height of x-ray power-platform due to its fiat energy response. The sub-peak after the main peak is proposed to be a result of the later-time additional implosion of plasma.
文摘We present a method,which combines the Gaussian decomposition method and the "distributed-lens" method,for analysing Z-scan curves of cascading nonlinear medium layers or a complicated cascading structure.A good agreement with the experimental data is obtained.The method would be useful to design optical limiters and to determine the nonlinearities of cascading medium layers.
基金The project supported by Pre-research Foundation of Chinese Acadeny of Engineering Physics(No.20010103)
文摘The experimental system for electrically exploding single metal wire has been designed and manufactured. Expansion of the dense plasma column formed from an electrically exploding Cu wire of diameter 30/~m has been studied with a high-speed photographer to obtain the time-dependent radius (R-t) curve. The experimental results demonstrate that the mean ex-pansion rate of the dense plasma column is 1.94μm/ns, 2.6μm/ns and 3.75μm/ns according to the peak pulse current 4.5 kA, 7 kA and 9.5 kA respectively. The results can be beneficial to giving a profound understanding of the early stage of wire-array Z-pinch physics and to improvement on their design.
文摘A hybrid model of MHD and kinetic theory is proposed to investigate the synergetic stabilizing effects of sheared axial flow and finite Larmor radius on the RayleighTaylor instability in Zpinch implosions.In our model the MHD plasma is considered to respond to a perturbation with exp at frequency ω+ik2⊥ρ2iΩi instead of frequency ω,where k2⊥ρ2i is the finite Larmor radius effects given from the general kinetic theory of magnetized plasma.Therefore linearized continuity and momentum equations include automatically the finite Larmor radius effects.Dispersion relation is derived,which includes the effects of a density discontinuity and the finite Larmor radius as well as a sheared flow that produces the KelvinHelmholtz instability.The dispersion equation is examined in three cases.The results indicate that the synergetic effect of sheared axial flow and the finite Larmor radius can mitigate both the RayleighTaylor instability and the hybrid RayleighTaylor/KelvinHelmholtz instability.Moreover,the synergetic mitigation effect is stronger than either of them acting separately.
