Generation of the second harmonic initiated by Bell-Plesset effects in a cylindrical geometry is studied analytically. For an initial single-mode velocity perturSation, the second-order mode-coupling formula is obtain...Generation of the second harmonic initiated by Bell-Plesset effects in a cylindrical geometry is studied analytically. For an initial single-mode velocity perturSation, the second-order mode-coupling formula is obtained by expanding the perturbation displacement and velocity potential up to the second-order accuracy. It is found that the initially symmetric interface evolves into a significant bubble-spike asymmetric pattern. The second-order solutions clearly show that the amplitude of the spike grows faster than that of the buSble. The temporal evolutions of the amplitudes of the 5ubSie and spike are dependent on the interface velocity Vo. The larger interface velocity leads to the smaller amplitude of the perturbation at an arbitrary interface position in a cylindrically convergent geometry.展开更多
Effects of a continuous magnetic field in the direction of streaming on the incompressible Kelvin–Helmholtz instability （KHI） are investigated by solving the linear ideal magnetohydrodynamic equations. It is found ...Effects of a continuous magnetic field in the direction of streaming on the incompressible Kelvin–Helmholtz instability （KHI） are investigated by solving the linear ideal magnetohydrodynamic equations. It is found that the frequency of the KHI is not influenced by the magnetic field. The magnetic field strength effect decreases the linear growth of the KHI, while the magnetic field gradient scale length effect increases its linear growth. The KHI can even be completely suppressed when the magnetic field is strong enough. The linear growth rate approaches a maximum when the magnetic field gradient scale length is large enough.展开更多
The sixth-order accurate phase error flux-corrected transport numerical algorithm is introduced, and used to simulate Kelvin-Helmholtz instability. Linear growth rates of the simulation agree with the linear theories ...The sixth-order accurate phase error flux-corrected transport numerical algorithm is introduced, and used to simulate Kelvin-Helmholtz instability. Linear growth rates of the simulation agree with the linear theories of Kelvin Helmholtz instability. It indicates the validity and accuracy of this simulation method. The method also has good capturing ability of the instability interface deformation.展开更多
This paper studies the phase effect in mode coupling of Kelvin-Helmholtz instability in two-dimensionalincompressible fluid.It is found that there is an important growth phenomenon of every mode in the mode couplingpr...This paper studies the phase effect in mode coupling of Kelvin-Helmholtz instability in two-dimensionalincompressible fluid.It is found that there is an important growth phenomenon of every mode in the mode couplingprocess.The growth changes periodically with phase difference and in the condition of our simulation the period is about0.7π.The period characteristic is apparent in all stage of the mode coupling process,especially in the relatively laterstage.展开更多
Intense lasing at 18.9 and 20.3nm in nickel-like molybdenum and niobium ions has been observed by using two 200ps laser pulses with total energy of 50 J at 1.053μm from XingGuang II laser facility.Their gain coeffici...Intense lasing at 18.9 and 20.3nm in nickel-like molybdenum and niobium ions has been observed by using two 200ps laser pulses with total energy of 50 J at 1.053μm from XingGuang II laser facility.Their gain coefficients were measured to be 1.6 and 1.5cm-1,respectively.This shows the possibility of extending Ni-like x-ray lasing in low-Z elements and paves the way towards small scale x-ray lasers for applications at university laboratories.展开更多
基金Supported by the National Natural Science Foundation of China under Grant Nos 11074300, 11075024, 11274026, and 11275031, the National Basic Research Program of China under Grant Nos 2013CB834100 and 2013CBA01504, and the National Science and Technology Major Project of the Ministry of Science and Technology of China under Grant Nos 2011ZX05038-001.
文摘Generation of the second harmonic initiated by Bell-Plesset effects in a cylindrical geometry is studied analytically. For an initial single-mode velocity perturSation, the second-order mode-coupling formula is obtained by expanding the perturbation displacement and velocity potential up to the second-order accuracy. It is found that the initially symmetric interface evolves into a significant bubble-spike asymmetric pattern. The second-order solutions clearly show that the amplitude of the spike grows faster than that of the buSble. The temporal evolutions of the amplitudes of the 5ubSie and spike are dependent on the interface velocity Vo. The larger interface velocity leads to the smaller amplitude of the perturbation at an arbitrary interface position in a cylindrically convergent geometry.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11275031, 11075024, 11274026 and 11074300, and the National Basic Research Program of China under Grant Nos 2013CB834100 and 2013CBA01504.
文摘Effects of a continuous magnetic field in the direction of streaming on the incompressible Kelvin–Helmholtz instability （KHI） are investigated by solving the linear ideal magnetohydrodynamic equations. It is found that the frequency of the KHI is not influenced by the magnetic field. The magnetic field strength effect decreases the linear growth of the KHI, while the magnetic field gradient scale length effect increases its linear growth. The KHI can even be completely suppressed when the magnetic field is strong enough. The linear growth rate approaches a maximum when the magnetic field gradient scale length is large enough.
基金supported by the National Basic Research Program(973 Program)under Grant No.2007CB815100the Research Fund for the Doctoral Program of Higher Education of China under Grant No.20070290008
文摘The sixth-order accurate phase error flux-corrected transport numerical algorithm is introduced, and used to simulate Kelvin-Helmholtz instability. Linear growth rates of the simulation agree with the linear theories of Kelvin Helmholtz instability. It indicates the validity and accuracy of this simulation method. The method also has good capturing ability of the instability interface deformation.
基金Supported by the National Basic Research Program of China under Grant No.2007CB815100the Research Fund for the Doctoral Program of Higher Education of China under Grant No.20070290008the National Natural Science Foundation of China under Grant Nos.10775020 and 10874242
文摘This paper studies the phase effect in mode coupling of Kelvin-Helmholtz instability in two-dimensionalincompressible fluid.It is found that there is an important growth phenomenon of every mode in the mode couplingprocess.The growth changes periodically with phase difference and in the condition of our simulation the period is about0.7π.The period characteristic is apparent in all stage of the mode coupling process,especially in the relatively laterstage.
基金the National 863 High Technology Program of China(863-410).
文摘Intense lasing at 18.9 and 20.3nm in nickel-like molybdenum and niobium ions has been observed by using two 200ps laser pulses with total energy of 50 J at 1.053μm from XingGuang II laser facility.Their gain coefficients were measured to be 1.6 and 1.5cm-1,respectively.This shows the possibility of extending Ni-like x-ray lasing in low-Z elements and paves the way towards small scale x-ray lasers for applications at university laboratories.
