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
Currently,the neutron yield of Z-Pinch is lower than that of laser driven fusion.In the neutron imaging for this facility,the signal to noise ratio(SNR)has a significant influence on the expected spatial resolution of...Currently,the neutron yield of Z-Pinch is lower than that of laser driven fusion.In the neutron imaging for this facility,the signal to noise ratio(SNR)has a significant influence on the expected spatial resolution of the reconstructed fusion core,especially in the condition of low neutron yield.In this paper,mathematical model is purposed to describe the dependence of aperture parameters on the imaging SNR.The investigation shows that the imaging SNR is closely related to the size of contrast boundary on the point spread function.According to this,a novel non-uniform redundancy penumbra apertures array is designed.In addition,the imaging performances of this novel coded aperture,penumbra aperture and ring aperture are evaluated and compared by Monte Carlo method.The comparison shows that this novel aperture has significant advantage compared to the penumbra aperture which is commonly used for neutron imaging with low yield.The encouraging results can provide reference for the optimal design of the coded aperture used in the neutron imaging for Z-pinch driven fusion with low neutron yield.展开更多
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.
基金supported by the National Natural Science Foundation of China(Grant No.10975113)Innovative Research Team in University of Ministry of Education of China(Nuclear Energy Science and Engineering)(Grant No.IRT1280)
文摘Currently,the neutron yield of Z-Pinch is lower than that of laser driven fusion.In the neutron imaging for this facility,the signal to noise ratio(SNR)has a significant influence on the expected spatial resolution of the reconstructed fusion core,especially in the condition of low neutron yield.In this paper,mathematical model is purposed to describe the dependence of aperture parameters on the imaging SNR.The investigation shows that the imaging SNR is closely related to the size of contrast boundary on the point spread function.According to this,a novel non-uniform redundancy penumbra apertures array is designed.In addition,the imaging performances of this novel coded aperture,penumbra aperture and ring aperture are evaluated and compared by Monte Carlo method.The comparison shows that this novel aperture has significant advantage compared to the penumbra aperture which is commonly used for neutron imaging with low yield.The encouraging results can provide reference for the optimal design of the coded aperture used in the neutron imaging for Z-pinch driven fusion with low neutron yield.
