Chen Baozhen

A new algorithm for X-ray transmission through a cylinder capillary

Abstract A new algorithm for calculating the transmission efficiency of X-rays through a cylinder capillary is proposed. The algorithm is based on some reasonable physical and mathematical assumptions. Comparisons are made with previous algorithm published and with experimental results described in literature.

Superthermal Electron Produced in Relativistic Laser-Plasma Interaction

The dynamics of a relativistic electron submitted to an intense, plane wave, linearly polarized laser field is reviewed. Based on the dynamics, the temperature of the electron in the laser field is defined and calculated. It is found that the calculated temperature fits the first temperature observed in the experiment by Malka et al. A model to evaluate the electron temperature by taking the electron-ion scattering into account is proposed. It is found that when the electron temperature by considering the scattering, , is evidently larger than the electron temperature without considering the scattering, . This result is in favor of explaining the two-temperature distribution of the electron energy observed in the experiment by Malka et al.

Energetic above-threshold ionization spectra of H-atom in intense laser fields*

The above-threshold ionization (ATI) spectra of H-atom in intense laser fields (laser intensity I is up to 1018W/cm2) are calculated. It is found that the kinetic energy of the ejected electron at the location of the peak of the ATI spectra is about equal to the corresponding ponderomotive potential of the applied laser fields. This result is consistent with that obtained by Wilks et al. and fits the experimental results of the super thermal electron. A possible new mechanism of the super thermal electron generation is proposed.

Transmission Efficiency of X-Rays Through a Cylinder Capillary

A new model for calculating the transmission efficiency of x-rays through a cylinder capillary is proposed. The model is based on some reasonable physical and mathematical assumptions. The calculation results given by the model have satisfactory intrinsic consistency and can get quite a good fit to the experimental results.

A new derivation of Keldysh's formula

In this letter, a new derivation of Keldyshs formula is presented and a brief discussion about the comparison between the new derivation and the original one is given.

Third-Harmonic Generated in EH32 Mode of a Gas-Filled WavegUide by fs Laser Pulses

In this paper it is reported for the first time that the third harmonic generated in EH32 mode of a gas-filled waveguide by fs pulses has higher generation efficiency. The new finding contrasts with the experiment in [C.G. Durfee III, S. Backus, M.M. Murnane, and H.C. Kapteyn, Opt. Lett. 22 (1997) 1565]. Some possible factors, which produce the contradiction, are discussed briefly.

Signal-Pressure Curves of Cascaded Four-Wave Mixing in Gas-Filled Capillary by fs Pulses

The theoretical framework for the cascaded four waves mixing (CFWM) in gas-filled capillary by fs pulses is constructed. Based on the theoretical framework, the signal-pressure curves (SPC) of the CFWM in gas-filled capillary by fs pulses are calculated. With a comparison between the theoretical and experimental SPC we have discussed the influence of the walk-off and phase modulation on the SPC. At the same time, we have discussed the possible origin of the first three peaks of the SPC.

Theoretical Description of the Third Order Parametric Wave Mixing in a Gas-Filled Capillary of Femto-Second Laser Pulse*

The theoretical signal-pressure curves are calculated from approximate analytical solutions of the coupled equations describing the third order parametric wave mixing in a gas-filled capillary of femto-second laser pulses. The comparison with the corresponding experimental curves suggests that the following three factors exert important influences on the degree of fitting between the theoretical and experimental results: the walk-off, the phase modulation, and the third order harmonic of idler pulse.

Relativistic semi-classical theory of atom ionization in ultra-intense laser

A relativistic semi-classical theory (RSCT) of H-atom ionization in ultra-intense laser (UIL) is proposed. A relativistic analytical expression for ionization probability of H-atom in its ground state is given. This expression, compared with non-relativistic expression, clearly shows the effects of the magnet vector in the laser, the non-dipole approximation and the relativistic mass-energy relation on the ionization processes. At the same time, we show that under some conditions the relativistic expression reduces to the non-relativistic expression of non-dipole approximation. At last, some possible applications of the relativistic theory are briefly stated.A relativistic semi-classical theory (RSCT) of H-atom ionization in ultra-intense laser (UIL) is proposed. A relativistic analytical expression for ionization probability of H-atom in its ground state is given. This expression, compared with non-relativistic expression, clearly shows the effects of the magnet vector in the laser, the non-dipole approximation and the relativistic mass-energy relation on the ionization processes. At the same time, we show that under some conditions the relativistic expression reduces to the non-relativistic expression of non-dipole approximation. At last, some possible applications of the relativistic theory are briefly stated.

Supra-thermal Electron Generation at Moderate Laser Intensity*

The effects of re-scattering on the supra-thermal electron (STE) produced in moderate laser fields are analytically considered (laser intensity is up to ) with a simple model. The electron kinetic energy distribution given by the model is consistent to that given by the particle-in-cell simulation. Based on this fact, it is shown that the scattering of electron in intense laser by the ion in plasma plays an important role in the generation of STE in a moderate laser field.