For the purpose of ensuring normal operations of Shenzhou (SZ) series of manned spacecrafts and cosmonauts' safety, Space Environment Monitors (SEM)are mounted on board SZ-2, 3, 4, 5. SEMs aim to detect the high e...For the purpose of ensuring normal operations of Shenzhou (SZ) series of manned spacecrafts and cosmonauts' safety, Space Environment Monitors (SEM)are mounted on board SZ-2, 3, 4, 5. SEMs aim to detect the high energy particles, the low energy particles, charging potential, atmospheric desity and composition. Detection of SEMs enable us to understand better the space environment in the manned spacecraft's orbit, and to provide a good space environment services for the spacecraft and cosmonauts. In addition, by using the data from SEMs, we have achieved some scientific accomplishments, such as the energy spectra of precipitating electrons, the abnormal variety of atmospheric density and composition during geomagnetic disturbances, the electron angle distribution in the low orbit and so on.展开更多
Based on the measurements made by Atmospheric Density Detectors(ADDs) onboard Chinese spacecraft Shenzhou 2-4,the variations of thermosphere density are revealed.During the quiet period,the density at spacecraft altit...Based on the measurements made by Atmospheric Density Detectors(ADDs) onboard Chinese spacecraft Shenzhou 2-4,the variations of thermosphere density are revealed.During the quiet period,the density at spacecraft altitude of 330~410 km exhibited a dominant diurnal variation,with high value on dayside and low value on nightside.The ratio of the diurnal maximum density to the minimum ranged from 1.7 to 2.0.The ratio shows a positive correlation with the level of solar activity and a negative correlation with the level of geomagnetic activity.When a geomagnetic disturbance comes,the atmospheric density at the altitude of 330～410 km displayed a global enhancement.For a strong geomagnetic disturbance,the atmospheric density increased by about 56%,and reached its maximum about 6～7 hours after the geomagnetic disturbance peak. The density asymmetry was also observed both in the southern and northern hemisphere during the geomagnetic disturbance peak.展开更多
Geometric factor is the key parameter for inversion of particle spectrum in space particle detection. Traditional geometric factor is obtained through the method of numerical calculation with the actual structure of t...Geometric factor is the key parameter for inversion of particle spectrum in space particle detection. Traditional geometric factor is obtained through the method of numerical calculation with the actual structure of the detector as the input condition. The degree of accuracy for data inversion is reduced since traditional geometric factor fails to take into account the physical process of interaction between the particle and substance as well as the influence of factors such as the particle interference between different energy channels on the measurement result. Here we propose an improved geometrical factor calculation method, the concept of which is to conduct actual structural modelling of the detector in the GEANT4 program, consider the process of interaction between the particle and substance, obtain the response function of the detector to particles of different energy channels through the method of Monte Carlo simulation, calculate the influence of contaminated particle on the geometrical factor, and finally get the geometrical factors for different energy channels of the detector. The imrpoved geometrical factor obtained through the method has carried out inversion for the data of high energy protons detector on China's FY-3 satellite, the energy spectrum after which is more in line with the power law distribution recognized by space physics. The comparison with the measured result of POES satellite indicates that the FY-3 satellite data are in good accordance with the satellite data, which shows the method may effectively improve the quality of data inversion.展开更多
Cross-calibration of high energetic particle data is a primary requirement for the availability of multi-instrument, multi-spacecraft data. II also can provide a method to verify relative reliability of data from sing...Cross-calibration of high energetic particle data is a primary requirement for the availability of multi-instrument, multi-spacecraft data. II also can provide a method to verify relative reliability of data from single satellite measurement. This pa- per presents a case study of energetic particles data cross-calibration between FY-3B and NOAA-17. A generally good agree- ment is acquired in the flux values and distribution trend of 2.5-6.9 MeV protons and 0.3-1.1 MeV electrons between FY-3B and NOAA-17 satellites. It suggests that the data observed by FY-3B is properly cross-calibrated. We can also confirm that energetic particles data observed by FY-3B satellite is available.展开更多
The space environment monitor(SEM)aboard FY-2 satellite consists of the high energy particle detector(HEPD)and the solar X-ray flux detector(SXFD).The SEM can provide real-time monitoring of flare and solar proton eve...The space environment monitor(SEM)aboard FY-2 satellite consists of the high energy particle detector(HEPD)and the solar X-ray flux detector(SXFD).The SEM can provide real-time monitoring of flare and solar proton event for its operation at geostationary orbit and is also the first Chinese space system for monitoring and alerting solar proton event.During the 23rd solar maximum cycle,almost all the solar proton events that took place in this period are monitored and some of them are predicted successfully by analyzing the characteristics of X-ray flare monitored by the SEM.Some basic variation characteristics of particle at geostationary orbit are found such as day-night periodic variation of particle flux,the electron flux with energy>1.4 MeV in the scope from 10 to 200/cm^(2).s-sr and the proton flux with energy>1.1 MeV in the scope from 600 to 8000/cm^(2)-s.sr during the time with no magnetic storm and solar eruption.展开更多
文摘For the purpose of ensuring normal operations of Shenzhou (SZ) series of manned spacecrafts and cosmonauts' safety, Space Environment Monitors (SEM)are mounted on board SZ-2, 3, 4, 5. SEMs aim to detect the high energy particles, the low energy particles, charging potential, atmospheric desity and composition. Detection of SEMs enable us to understand better the space environment in the manned spacecraft's orbit, and to provide a good space environment services for the spacecraft and cosmonauts. In addition, by using the data from SEMs, we have achieved some scientific accomplishments, such as the energy spectra of precipitating electrons, the abnormal variety of atmospheric density and composition during geomagnetic disturbances, the electron angle distribution in the low orbit and so on.
文摘Based on the measurements made by Atmospheric Density Detectors(ADDs) onboard Chinese spacecraft Shenzhou 2-4,the variations of thermosphere density are revealed.During the quiet period,the density at spacecraft altitude of 330~410 km exhibited a dominant diurnal variation,with high value on dayside and low value on nightside.The ratio of the diurnal maximum density to the minimum ranged from 1.7 to 2.0.The ratio shows a positive correlation with the level of solar activity and a negative correlation with the level of geomagnetic activity.When a geomagnetic disturbance comes,the atmospheric density at the altitude of 330～410 km displayed a global enhancement.For a strong geomagnetic disturbance,the atmospheric density increased by about 56%,and reached its maximum about 6～7 hours after the geomagnetic disturbance peak. The density asymmetry was also observed both in the southern and northern hemisphere during the geomagnetic disturbance peak.
基金supported by the National Natural Science Foundation of China(Grant No.41204119)the Space Science Strategic Pioneer Program of CAS(Grant No.XDA04060804)
文摘Geometric factor is the key parameter for inversion of particle spectrum in space particle detection. Traditional geometric factor is obtained through the method of numerical calculation with the actual structure of the detector as the input condition. The degree of accuracy for data inversion is reduced since traditional geometric factor fails to take into account the physical process of interaction between the particle and substance as well as the influence of factors such as the particle interference between different energy channels on the measurement result. Here we propose an improved geometrical factor calculation method, the concept of which is to conduct actual structural modelling of the detector in the GEANT4 program, consider the process of interaction between the particle and substance, obtain the response function of the detector to particles of different energy channels through the method of Monte Carlo simulation, calculate the influence of contaminated particle on the geometrical factor, and finally get the geometrical factors for different energy channels of the detector. The imrpoved geometrical factor obtained through the method has carried out inversion for the data of high energy protons detector on China's FY-3 satellite, the energy spectrum after which is more in line with the power law distribution recognized by space physics. The comparison with the measured result of POES satellite indicates that the FY-3 satellite data are in good accordance with the satellite data, which shows the method may effectively improve the quality of data inversion.
基金supported by the National Natural Science Foundation of China(Grant No.41204119)
文摘Cross-calibration of high energetic particle data is a primary requirement for the availability of multi-instrument, multi-spacecraft data. II also can provide a method to verify relative reliability of data from single satellite measurement. This pa- per presents a case study of energetic particles data cross-calibration between FY-3B and NOAA-17. A generally good agree- ment is acquired in the flux values and distribution trend of 2.5-6.9 MeV protons and 0.3-1.1 MeV electrons between FY-3B and NOAA-17 satellites. It suggests that the data observed by FY-3B is properly cross-calibrated. We can also confirm that energetic particles data observed by FY-3B satellite is available.
文摘The space environment monitor(SEM)aboard FY-2 satellite consists of the high energy particle detector(HEPD)and the solar X-ray flux detector(SXFD).The SEM can provide real-time monitoring of flare and solar proton event for its operation at geostationary orbit and is also the first Chinese space system for monitoring and alerting solar proton event.During the 23rd solar maximum cycle,almost all the solar proton events that took place in this period are monitored and some of them are predicted successfully by analyzing the characteristics of X-ray flare monitored by the SEM.Some basic variation characteristics of particle at geostationary orbit are found such as day-night periodic variation of particle flux,the electron flux with energy>1.4 MeV in the scope from 10 to 200/cm^(2).s-sr and the proton flux with energy>1.1 MeV in the scope from 600 to 8000/cm^(2)-s.sr during the time with no magnetic storm and solar eruption.
