Deep dielectric charging/discharging,caused by high energy electrons,is an important consideration in electronic devices used in space environments because it can lead to spacecraft anomalies and failures.The Jovian p...Deep dielectric charging/discharging,caused by high energy electrons,is an important consideration in electronic devices used in space environments because it can lead to spacecraft anomalies and failures.The Jovian planets,including Saturn,Uranus,Neptune and Jupiter’s moons,are believed to have robust electron radiation belts at relativistic energies.In particular,Jupiter is thought to have caused at least 42 internal electrostatic discharge events during the Voyager 1 flyby.With the development of deep space exploration,there is an increased focus on the deep dielectric charging effects in the orbits of Jovian planets.In this paper,GEANT4,a Monte Carlo toolkit,and radiation-induced conductivity(RIC)are used to calculate deep dielectric charging effects for Jovian planets.The results are compared with the criteria for preventing deep dielectric charging effects in Earth orbit.The findings show that effective criteria used in Earth orbit are not always appropriate for preventing deep dielectric charging effects in Jovian orbits.Generally,Io,Europa,Saturn(R_S=6),Uranus(L=4.73)and Ganymede missions should have a thicker shield or higher dielectric conductivity,while Neptune(L=7.4)and Callisto missions can have a thinner shield thickness or a lower dielectric conductivity.Moreover,dielectrics grounded with double metal layers and thinner dielectrics can also decrease the likelihood of discharges.展开更多
In this article, we assume that the （0^＋,1^＋） strange-bottom mesons are the conventional bs mesons, and calculate the electromagnetic coupling constants d, g1, g2, and g3 using the light-cone QGD sum rules. Then w...In this article, we assume that the （0^＋,1^＋） strange-bottom mesons are the conventional bs mesons, and calculate the electromagnetic coupling constants d, g1, g2, and g3 using the light-cone QGD sum rules. Then we study the radiative decays Bs0→Bs^＊γ, Bs1→Bsγ, Bs1→Bs^＊γ, and Bs1→Bs0γ, and observe that the widths are rather narrow. We can search for the （0^＋, 1^＋） strange-bottom mesons in the invariant Bsπ^0 and Bs^＊π^0 mass distributions in the strong decays or in the invariant Bs^＊γ, and Bsγ mass distributions in the radiative decays.展开更多
Blazars are subclass of AGN （active galactic nuclei） with relativistic jet that is pointing in the general direction of the earth. The energy flux in the jet is about （10^44-10^47） erg/s. The γ-rays in the energy...Blazars are subclass of AGN （active galactic nuclei） with relativistic jet that is pointing in the general direction of the earth. The energy flux in the jet is about （10^44-10^47） erg/s. The γ-rays in the energy range 10 GeV-10 TeV emanating from blazar are examined and their effect on the IGM （intergalactic medium） is studied. The γ-ray emission is considered as due to inverse Compton scattering of relativistic electrons. There appears to be a gamma ray flux from blazar above 10 GeV having a line intensity of 1.5 × 10^-4 cm^-2 s^-1 sr^-1. The IGM is measured to large distances and it is found to be clumpy. It is found that at higher redshifl the density of IGM increases. The cosmological density parameter measured is found to lie within the suggested limit of 0.03 at redshift z = 3 for background intensity of radiation 10^-24 W·m^-2·Hz^-1·sr^-1. The iso-ΩIGM curve shows a kink in its profile which might be significant at the particular value of z equal to 2. Some more detailed studies are required for understanding the distribution of intergalactic medium at the unstable point at z = 2 as shown in inverse Compton radiation.展开更多
The paper analyze the polarization of study dielectric that produced field by dipole, medium field plays an important role in electromagnetic wave radiation. The electric field expression for electric dipole electric ...The paper analyze the polarization of study dielectric that produced field by dipole, medium field plays an important role in electromagnetic wave radiation. The electric field expression for electric dipole electric field distribution in ordinary textbooks only give a special direction, This paper introduces in detail the formula of the electric dipole in the space of an arbitrary point excitation electric field, and use computer sottware to simulate the distribution pattern of electric dipole, and gives some typical figures for reference.展开更多
基金supported by Beijing Municipal Natural Science Foundation-Quantitative Research on Mitigating Deep Dielectric Charging Effects in Jupiter orbits(No.3184048)National Key Scientific Instrument and Equipment Development Projects,China(No.2012YQ03014207)。
文摘Deep dielectric charging/discharging,caused by high energy electrons,is an important consideration in electronic devices used in space environments because it can lead to spacecraft anomalies and failures.The Jovian planets,including Saturn,Uranus,Neptune and Jupiter’s moons,are believed to have robust electron radiation belts at relativistic energies.In particular,Jupiter is thought to have caused at least 42 internal electrostatic discharge events during the Voyager 1 flyby.With the development of deep space exploration,there is an increased focus on the deep dielectric charging effects in the orbits of Jovian planets.In this paper,GEANT4,a Monte Carlo toolkit,and radiation-induced conductivity(RIC)are used to calculate deep dielectric charging effects for Jovian planets.The results are compared with the criteria for preventing deep dielectric charging effects in Earth orbit.The findings show that effective criteria used in Earth orbit are not always appropriate for preventing deep dielectric charging effects in Jovian orbits.Generally,Io,Europa,Saturn(R_S=6),Uranus(L=4.73)and Ganymede missions should have a thicker shield or higher dielectric conductivity,while Neptune(L=7.4)and Callisto missions can have a thinner shield thickness or a lower dielectric conductivity.Moreover,dielectrics grounded with double metal layers and thinner dielectrics can also decrease the likelihood of discharges.
基金Supported by National Natural Science Foundation of China under Grant No.10775051Program for New Century Excellent Talents in Universities under Grant No.NCET-07-0282
文摘In this article, we assume that the （0^＋,1^＋） strange-bottom mesons are the conventional bs mesons, and calculate the electromagnetic coupling constants d, g1, g2, and g3 using the light-cone QGD sum rules. Then we study the radiative decays Bs0→Bs^＊γ, Bs1→Bsγ, Bs1→Bs^＊γ, and Bs1→Bs0γ, and observe that the widths are rather narrow. We can search for the （0^＋, 1^＋） strange-bottom mesons in the invariant Bsπ^0 and Bs^＊π^0 mass distributions in the strong decays or in the invariant Bs^＊γ, and Bsγ mass distributions in the radiative decays.
文摘Blazars are subclass of AGN （active galactic nuclei） with relativistic jet that is pointing in the general direction of the earth. The energy flux in the jet is about （10^44-10^47） erg/s. The γ-rays in the energy range 10 GeV-10 TeV emanating from blazar are examined and their effect on the IGM （intergalactic medium） is studied. The γ-ray emission is considered as due to inverse Compton scattering of relativistic electrons. There appears to be a gamma ray flux from blazar above 10 GeV having a line intensity of 1.5 × 10^-4 cm^-2 s^-1 sr^-1. The IGM is measured to large distances and it is found to be clumpy. It is found that at higher redshifl the density of IGM increases. The cosmological density parameter measured is found to lie within the suggested limit of 0.03 at redshift z = 3 for background intensity of radiation 10^-24 W·m^-2·Hz^-1·sr^-1. The iso-ΩIGM curve shows a kink in its profile which might be significant at the particular value of z equal to 2. Some more detailed studies are required for understanding the distribution of intergalactic medium at the unstable point at z = 2 as shown in inverse Compton radiation.
文摘The paper analyze the polarization of study dielectric that produced field by dipole, medium field plays an important role in electromagnetic wave radiation. The electric field expression for electric dipole electric field distribution in ordinary textbooks only give a special direction, This paper introduces in detail the formula of the electric dipole in the space of an arbitrary point excitation electric field, and use computer sottware to simulate the distribution pattern of electric dipole, and gives some typical figures for reference.
