For the analysis of high-order harmonics generated in a long gas jet by intense chirped femtosecond laser pulses, calculations of the laser propagation and harmonic generation were performed in terms of a nonadiabatic three-dimensional model. The self-guided propagation, observed at the conditions of bright harmonic generation, was confirmed by the model calculations. When using negatively chirped pulses, the calculated distribution of the harmonic field is spatially and spectrally confined, being generated on axis with a narrow spectral profile. The positively chirped pulses generate broad spectral distribution on axis, and narrow off axis, but in the latter case with a large emission angle. The estimation of harmonic beam divergence agreed well with experimentally measured data, showing the lowest divergence at the conditions of the brightest harmonic generation. Spectral, temporal, and spatial modifications of the propagated laser pulse are found to influence decisively the single-atom response and ultimately the harmonic field, providing a coherent picture of harmonic generation.

We present a time-dependent analysis of high-order harmonics generated by a self-guided femtosecond laser pulse propagating through a long gas jet. A three-dimensional model is used to calculate the harmonic fields generated by laser pulses, which only differ by the sign of their initial chirp. The time-frequency distributions of the single-atom dipole and harmonic field reveal the dynamics of harmonic generation in the cutoff. A time-dependent phase-matching calculation was performed, taking into account the self-phase modulation of the laser field. Good phase matching holds for only few optical cycles, being dependent on the electron trajectory. When the cutoff trajectory is phase matched, emitted harmonics are locked in phase and the emission intensity is maximized.

We report the detection of the C IV λλ1548, 1551 emission line in the region of the RCW 114 nebula using the FIMS/SPEAR data. The observed C IV line intensity indicates that RCW 114 is much closer to us than WR 90, a Wolf-Rayet star that was thought to be associated with RCW 114 in some of the previous studies. We also found the existence of a small H I bubble centered on WR 90, with a different local standard of rest velocity range from that of the large H I bubble which was identified previously as related to RCW 114. These findings imply that the RCW 114 nebula is likely an old supernova remnant which is not associated with WR 90. Additionally, the global morphologies of the C IV, Hα, and H I emissions show that RCW 114 has evolved in a non-uniform interstellar medium.

We present the first far-ultraviolet (FUV) emission-line morphologies of the whole region of the supernova remnant (SNR) G65.3+5.7 using the FIMS/SPEAR data. The morphologies of the C iv λλ1548, 1551, He ii λ1640, and O iii] λλ1661, 1666 lines appear to be closely related to the optical and/or soft X-ray images obtained in previous studies. Dramatic differences between the C iv morphology and the optical [O iii] λ5007 image provide clues to a large resonant-scattering region and a foreground dust cloud. The FUV morphologies also reveal the overall distribution of various shocks in different evolutionary phases and an evolutionary asymmetry between the east and the southwest sides in terms of Galactic coordinates, possibly due to a Galactic density gradient in the global scale. The relative X-ray luminosity of G65.3+5.7 to C iv luminosity is considerably lower than those of the Cygnus Loop and the Vela SNRs. This implies that G65.3+5.7 has almost evolved into the radiative stage in the global sense and supports the previous proposal that G65.3+5.7 has lost its bright X-ray shell and become a member of mixed-morphology SNRs as it has evolved beyond the adiabatic stage.