Photometric Calibration of the Barium Cloud Image in a Space Active Experiment： Determining the Release Efficiency

The barium release experiment is an effective method to explore the near-earth environment and to study all kinds of space physics processes. The first space barium release experiment in China was successfully carried out by a sounding rocket on April 5, 2013. This work is devoted to calculating the release efficiency of the barium release by analyzing the optical image observed during the experiment. First, we present a method to calibrate the images grey value of barium cloud with the reference stars to obtain the radiant fluxes at different moments. Then the release efficiency is obtained by a curve fitting with the theoretical evolution model of barium cloud. The calculated result is basically consistent with the test value on ground.     

基于光反馈双模DFB激光器的宽带混沌信号产生

提出并数值验证了一种利用光反馈双模分布式反馈(DM-DFB)半导体激光器产生宽带混沌信号的方法.通过双纵模Lang-Kobayashi方程建立了光反馈DM-DFB半导体激光器的理论模型,探明了宽带混沌信号产生的物理机制为模式拍频,数值分析了模式间隔、偏置电流和反馈系数对混沌带宽的影响.仿真设计了双模激光器,在镜面反馈系统中,高偏置电流和强反馈强度条件下可以产生38.6 GHz的混沌信号.这一结构为宽带集成混沌源提供了一种新思路.     

Nightside Martian Ionosphere Produced by Electron Impact Ionization

Based on the Martian magnetic field model established by magnetohydrodynamics simulation, we determine the possible precipitation areas of the solar wind electron in the nightside Martian atmosphere, and analyze the electron impact ionization to estimate the height of the nightside Martian ionospheric peak and the electron density profile using the energy flux analysis method. The influences of the single electron energy, electron energy density and ionization efficiency on the altitude of the ionospheric peak and the electron density profile are also investigated. Our results show that the solar wind electron moves along the V-shaped solar wind magnetic field lines, to precipitate into the Martian atmosphere. Due to the crustal magnetic field, the precipitation regions on the nightside are quite narrow and unstable. The impact ionization happens at the altitude of 130-500km, and the height of the ionospheric peak is around 170km, with a peak electron density of 3.0×10^3 cm^-3. The simulation results are consistent with the results from Mars 4/5 and Viking occultation measurements.