Phase Effects of Long-Wavelength Rayleigh–Taylor Instability on the Thin Shell

Taking the long-wavelength Rayleigh-Taylor instability(RTI) on the thin shell of inertial confinement fusion as the research object,a linear analytical model is presented to study the phase effects that are caused by the phase difference of single-mode perturbations on the two interfaces.Its accuracy is tested by numerical simulations.By analyzing the characteristic of this model,it is found that the phase difference does not change the basic RTI structure(only one spike and one bubble in a period).However,the symmetry of the spike and bubble is destroyed,which has non-expected influences on the convergent motion of ICF targets.Meanwhile,the phenomenon that the distance between spikes and bubbles along the vertical direction of acceleration differs by π is demonstrated.It is also shown that when the phase difference is large,the temporal evolution of the RTI is more serious and the thin target is easier to tend to break.

Comparison of Intraperitoneal and Intratesticular GY Y4137 Therapy for the Treatment of Testicular Ischemia Reperfusion Injury in Rats

The efficacy of intraperitoneal GY Y4137 therapy and intratesticular GY Y4137 therapy in an experimental rat model was investigated.Four groups were set up as the sham-operation group,torsion/detorsion(T/D)group,T/D plus intraperitoneal GY Y4137(G-IP)group,and T/D plus intratesticular GY Y4137(G-IT)group.In order to establish a testicular T/D model,the left testis was opcrated and the rotation reached 720°clockwise which lasted 1 h before reperfiusion.The G-IP group accepted 100 umol/kg of GY Y4137 intraperitoneally 30 min after testicular rotation,while the G-IT group was treated with the same dose by intratesticular injection.Six h after detorsion,the testis was collcted and subsequently asssed.The T/D group showed signifcant changes in histology and an enhancement in the level of oxidative stress and apoptosis compared to the sham-operation group.The expression of Caspase-3 and Bax turmed out to be strengthened by T/D and relatively decreased with GY Y4137 treatment in both the G-IP and G-IT groups.Moreover,the Bcl-2 expression was inhibited in the T/D group,and promoted by GYY4137 in the G-IP and G-IT groups.GYY4137,moderating these observed changes,displayed a more protective cffect with G-IT therapy than G-IP therapy.This study indicated that the efficacy of intratesticular therapy with GYY4137 is better than that of intraperitoneal therapy,which may provide a more valuable approach for testicular torsion therapy.

Weakly Nonlinear Rayleigh–Taylor Instability in Cylindrically Convergent Geometry

The Rayleigh–Taylor instability（RTI） in cylindrical geometry is investigated analytically through a second-order weakly nonlinear（WN） theory considering the Bell–Plesset（BP） effect. The governing equations for the combined perturbation growth are derived. The WN solutions for an exponentially convergent cylinder are obtained. It is found that the BP and RTI growths are strongly coupled, which results in the bubble-spike asymmetric structure in the WN stage. The large Atwood number leads to the large deformation of the convergent interface. The amplitude of the spike grows faster than that of the bubble especially for large mode number m and large Atwood number A. The averaged interface radius is small for large mode number perturbation due to the mode-coupling effect.

Simulation of the Weakly Nonlinear Rayleigh–Taylor Instability in Spherical Geometry

The Rayleigh-Taylor instability at the weakly nonlinear(WN)stage in spherical geometry is studied by numerical simulation.The mode coupling processes are revealed.The results are consistent with the WN model based on parameter expansion,while higher order effects are found to be non-negligible.For Legendre mode perturbation Pn(cos B),the nonlinear saturation amplitude(NSA)of the fundamental mode decreases with the mode number n.When n is large,the spherical NSA is lower than the corresponding planar one.However,for large n,the planar NSA can be recovered by applying Fourier transformation to the bubble/spike near the equator and calculating the NSA of the converted trigonometric harmonic.

Interface Width Effect on the Weakly Nonlinear Rayleigh–Taylor Instability in Spherical Geometry

Interface width effect on the spherical Rayleigh–Taylor instability in the weakly nonlinear regime is studied by numerical simulations.For Legendre perturbation mode Pn with wave number Kn and interface half-width L,the commonly adopted empirical linear growth rate formulaγnem(L)=γn/√1+KnL is found to be sufficient in spherical geometry.At the weakly nonlinear stage,the interface width affects the mode coupling processes.The development of the mode P2n is substantially influenced by the interface width.Moreover,the nonlinear saturation amplitude increases with the interface width.

Review of the current status of fast ignition research atthe IAPCM

We review the present status and future prospects of fast ignition(FI) research of the theoretical group at the IAPCM(Institute of Applied Physics and Computational Mathematics, Beijing) as a part of the inertial confinement fusion project. Since the approval of the FI project at the IAPCM, we have devoted our efforts to improving the integrated codes for FI and designing advanced targets together with the experimental group. Recent FI experiments [K. U. Akli et al., Phys. Rev. E 86, 065402(2012)] showed that the petawatt laser beam energy was not efficiently converted into the compressed core because of the beam divergence of relativistic electron beams. The coupling efficiency can be improved in three ways:(1) using a cone–wire-in-shell advanced target to enhance the transport efficiency,(2) using external magnetic fields to collimate fast electrons, and(3) reducing the prepulse level of the petawatt laser beam. The integrated codes for FI, named ICFI, including a radiation hydrodynamic code, a particle-in-cell(PIC) simulation code,and a hybrid fluid–PIC code, have been developed to design this advanced target at the IAPCM. The Shenguang-II upgraded laser facility has been constructed for FI research; it consists of eight beams(in total 24 kJ/3ω, 3 ns) for implosion compression, and a heating laser beam(0.5–1 kJ, 3–5 ps) for generating the relativistic electron beam. A fully integrated FI experiment is scheduled for the 2014 project.