1. Lecturer, Laboratory of Space New Technology, College of Astronautics, Nanjing Univ. of Aeronautics and Astronautics, Nanjing 210016, P.R. China.
2. Professor, Laboratory of Space New Technology, College of Astronautics, Nanjing Univ. of Aeronautics and Astronautics, Nanjing 210016, P.R. China (corresponding author).