[en] The planned inertial confinement fusion (ICF) ignition in China in around 2020 is to be accomplished in three steps. The first is carrying out target physics experiments in the existing laser facilities SG-II, SG-IIIP and SG-IIU (operating in 2012) of output energy 3-24 kJ at 3ω. Results have been obtained for better understanding the implosion dynamics and radiation transport. Recent studies include efficiency of radiation generation, hydrodynamic instabilities, shock waves in cryogenic targets, opacity measurements using kJ lasers, etc. Hydrodynamic codes (the LARED series) have been developed and experimentally verified with over 5000 shots, and are applied to investigating target physics and ignition target design. For fast ignition, a large number of experiments and numerical simulations have led to improved understanding relevant to target design, hot electron transport, collimation by the spontaneous magnetic fields in overdense plasmas, etc. In addition to the SG-II, SG-IIU and SG-IIIP, the SG-III laser facility with energy of 200-400 kJ at 3ω shall operate in 2014 and be used for advanced target physics research. In the last step, the 1.5 MJ SG-IV laser facility still under design will be used to investigate ignition and burning. (authors)

[en] The recent achievements of ICF research in China are reviewed. The constructions of laser facilities of SG-III and SG-IIUP are completed in this year and the full energy output operation will be in 2014. The target physics studies involving numerical simulations of a new ignition scheme, which is proposed to enhance implosion velocity and suppress hydrodynamic instability and distortion at interface between hot spot and main fuel, and experimental results (a few selected examples) are presented. (paper)

[en] Ten new members of the class of compact extragalactic HII regions or blue compact dwarf galaxies have been discovered in the direction of the Virgo cluster using objective prism plates from the UK Schmidt Telescope. Follow-up spectroscopy of five of the new galaxies shows them to be low-luminosity systems with strong narrow lines of large equivalent width. Velocities of three of the galaxies show them to be in the Virgo cluster. From plots of line ratios which separate objects according to excitation mechanism, there is no evidence for power-law excitation or broad line components in any of the galaxies. (author)

[en] The region of the Virgo cluster is the subject of an intensive quasar search, since quasars will provide valuable probes of absorption due to galaxy haloes and the intracluster medium. This paper presents data for 17 quasar candidates which have been observed spectroscopically, 15 of which are confirmed as quasars. With more than half of the emission-line and ultraviolet excess candidates now observed, the overall success rate for detecting quasars is approx.80 per cent. There appears to be a deficiency of quasars in the Virgo field by a factor of 2, when compared to other regions studied with the same technique. The distribution of quasars in Virgo has been compared with the galaxy distribution, using the most recent catalogue. There is no evidence for association between the quasars and Virgo galaxies, and application of Power Spectrum Analysis shows no evidence of clustering among the quasars. (author)

[en] Compared with central model, volume ignition has no hot spot, avoids the mixing at the hot-cold interface, the α-particle escaping, and the high convergence, greatly reduces the sharp demanding for uniformity. In laser indirect driving, from theoretical estimation and computational simulation, we have proved that using a tamper with good heat resistance, the DT fuel can be ignited in LTE at ∼3 KeV and then evolves to the non-LTE ignition at >5 KeV. In this case, 1 MJ radiation energy in the hohlraum could cause near 10 MJ output for a pellet with 0.2 mg DT fuel. We have compared results with and without α-particle transport, it shows that in the condition of ρR>0.5 g/cm² of DT fuel, both have the same results. For the system with ρR≅0.5 g/cm² we can use α-particle local deposition scheme. The non-uniformly doped tamper with density ρ≅1-5 g/cc can reduce mixing due to the small convergence ratio. The input energy is deposited in DT and tamper during the implosion, we try to reduce the tamper energy by changing the ratio of CH and doped Au and the thickness of the tamper

[en] Using objective-prism plates taken with the 44-arcmin objective prism mounted on the UK Schmidt telescope, 53 emission-line quasar candidates and 29 ultraviolet-excess objects (possible low-redshift quasars) have been found in a 5 x 5 degree² field in the Virgo cluster of galaxies. Eighteen of these 82 candidates were observed using the double spectrograph on the Palomar 5-metre telescope; 13 of the observed objects proved to be quasars. The broad-absorption-line QSO Q1232 + 134 is the first example of the class to show broad low-ionization absorption lines in addition to the usual high-excitation lines. Although no conclusive evidence is found for quasar-galaxy associations in this field, there do exist non-uniformities in the distribution of the quasar candidates, which may merit further investigation. (author)

[en] Nonlinear ablative single-mode Rayleigh–Taylor instability (RTI) with weak and strong preheatings has been investigated numerically. The numerical results for the linear growth rates obtained are in general agreement with a self-consistent linear stability analysis (Goncharov et al 1996 Phys. Plasmas 3 4665). The effects of preheating on the ablative RTI (ARTI) are shown to reduce its linear growth rate and mitigate the weakly nonlinear growth. It was found that the nonlinear evolution of the ARTI is strongly dependent on the preheating intensity and perturbation wavelength. There are three typical wavelength perturbations for the nonlinear evolution of the ARTI. In the ARTI with weak preheating, for a short-wavelength perturbation the spike can be ruptured in the highly nonlinear regime and for a middle/long-wavelength perturbation the Kelvin–Helmholtz mushroom-shaped patterns appear at the spike heads. In the ARTI with strong preheating for a middle-wavelength perturbation, jet-like spikes can be formed though the spikes can still be ruptured in its classical RTI (without thermal conductivity) counterpart. In summary, our numerical studies indicate that the preheating can have a pronounced influence on the nonlinear evolutions of the ARTI. Thus, it should be included in applications where preheating plays a vital role, such as inertial confinement fusion implosions and supernova explosions. (paper)

[en] A kinetic model describing the energy deposition of fast electrons is established by considering both binary collisions and contributions due to collective process. The collision term is exactly simplified by taking into account relativistic effects within the context of fast ignition, and the explicit formulation of relativistic kinetic equation in three-dimensional momentum space is obtained with the help of spherical harmonic expansion. The corresponding numerical code is developed and benchmarked physically. Typical case studies in fast ignition are also presented. (authors)

[en] The emittance of hot electrons produced from the interaction of a short-pulse and high intense laser with a relativistic plasma is an obstacle for igniting hot spot formation in the concept of fast ignition scheme for inertial confinement fusion. Our numerical results show that the tens of megagauss spontaneous quasistatic magnetic field generated by the short-pulse and high-intensity laser with a relativistic plasma may collimate hot electron motion. The spontaneous axial magnetic field driven by a helical current, parallel to laser propagation, behaves as a guiding center with a submicron Larmor radius. And the spontaneous toroidal magnetic field driven by ponderomotive current causes a pinch effect on hot electrons

[en] In this research, density gradient effects (i.e., finite thickness of ablation front effects) in ablative Rayleigh-Taylor instability (ARTI), in the presence of preheating within the weakly nonlinear regime, are investigated numerically. We analyze the weak, medium, and strong ablation surfaces which have different isodensity contours, respectively, to study the influences of finite thickness of ablation front on the weakly nonlinear behaviors of ARTI. Linear growth rates, generation coefficients of the second and the third harmonics, and coefficients of the third-order feedback to the fundamental mode are obtained. It is found that the linear growth rate which has a remarkable maximum, is reduced, especially when the perturbation wavelength λ is short and a cut-off perturbation wavelength λ_c appears when the perturbation wavelength λ is sufficiently short, where no higher harmonics exists when λ<λ_c. The phenomenon of third-order positive feedback to the fundamental mode near the λ_c[J. Sanz et al., Phys. Rev. Lett. 89, 195002 (2002); J. Garnier et al., Phys. Rev. Lett. 90, 185003 (2003); J. Garnier and L. Masse, Phys. Plasmas 12, 062707 (2005)] is confirmed in numerical simulations, and the physical mechanism of the third-order positive feedback is qualitatively discussed. Moreover, it is found that generations and growths of the second and the third harmonics are stabilized (suppressed and reduced) by the ablation effect. Meanwhile, the third-order negative feedback to the fundamental mode is also reduced by the ablation effect, and hence, the linear saturation amplitude (typically ∼0.2λ in our simulations) is increased significantly and therefore exceeds the classical prediction 0.1λ, especially for the strong ablation surface with a small perturbation wavelength. Overall, the ablation effect stabilizes the ARTI in the weakly nonlinear regime. Numerical results obtained are in general agreement with the recent weakly nonlinear theories and simulations as proposed [J. Sanz et al., Phys. Rev. Lett. 89, 195002 (2002); J. Garnier et al., Phys. Rev. Lett. 90, 185003 (2003); J. Garnier and L. Masse, Phys. Plasmas 12, 062707 (2005)].