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Self-injection and acceleration of monoenergetic electron beams from laser wakefield accelerators are first investigated in the highly relativistic regime, using 100 TW class, 27fs laser pulses. Quasi-monoenergetic multi-bunched beams with energies as high as multi-hundred MeV are observed with simultaneous measurements of side-scattering emissions that indicate the formation of self-channelling and self-injection of electrons into a plasma wake, referred to as a 'bubble'. The three-dimensional particle-in-cell simulations confirmed multiple self-injection of electron bunches into the bubble and their beam acceleration with gradient of 1.5GeV/cm.

We propose a geoacoustic inversion scheme employing a vector hydrophone array based on the fact that vector hydrophone can provide more acoustic field information than traditional pressure hydrophones. Firstly, the transmission loss of particle velocities is discussed. Secondly, the sediment sound speed is acquired by a matched-field processing (MFP) procedure, which is the optimization in combination of the pressure field and vertical particle velocity field. Finally, the bottom attenuation is estimated from the transmission loss difference between the vertical particle velocity and the pressure. The inversion method based on the vector hydrophone array mainly has two advantages: One is that the MFP method based on vector field can decrease the uncertain estimation of the sediment sound speed. The other is that the objective function based on the transmission loss difference has good sensitivity to the sediment attenuation and the inverted sediment attenuation is independent of source level. The validity of the inverted parameters is examined by comparison of the numerical results with the experimental data.

Two quite different Saha equations modified to a two-temperature plasma were proposed and employed in many literatures. In order to clear up this confusion phenomenon lasted for a few decades in the community of thermal plasma science and technology, this paper re-examines the thermodynamic derivation of the two-temperature Saha equations. It is pointed out that the modified Saha equation deduced by using the minimum Gibbs or Helmholtz free energy is incorrect for the two-temperature plasma. Instead, a more rigorous derivation is presented here from the basic thermodynamic principle that the entropy in an isolated system always assumes its maximum value at chemical equilibrium.

We synthesize the homogenous graphene films on cheap industrial Cu foils using low pressure chemical vapor deposition. The quality and the number of layers of graphene are characterized by Raman spectra. Through carefully tuning the growth parameters, we find that the growth temperature, hydrocarbon concentration and the growth time can substantially affect the growth of high-quality graphene. Both single and bilayer large size homogenous graphenes have been synthesized in optimized growth conditions. The growth of graphene on Cu surface is found to be self ceasing in the bilayer graphene process with the low solubility of carbon in Cu. Furthermore, we have optimized the transfer process, and clear graphene films almost free from impurity are successfully transferred onto Si/SiO2 substrates. The field effect transistors of bilayer graphene are fabricated, which demonstrates a maximum hole (electron) mobility of 4300 cm2 V?1s?1 (1920 cm2V?1s?1) at room temperature.