“Magnetic window”is considered as an effective method to solve the communication blackout issue.COMSOL software package based on the finite element method is utilized to simulate the propagation of right-handed circ...“Magnetic window”is considered as an effective method to solve the communication blackout issue.COMSOL software package based on the finite element method is utilized to simulate the propagation of right-handed circularly polarized wave in the magnetized plasma sheath.We assume a double Gaussian model of electron density and an exponential attenuation model of magnetic field.The propagation characteristics of right-handed circularly polarized wave are analyzed by the observation of the reflected,transmitted and loss coefficient.The numerical results show that the propagation of right-handed circularly polarized wave in the magnetized plasma sheath varies for different incident angles,collision frequencies,non-uniform magnetic fields and non-uniform plasma densities.We notice that reducing the wave frequency can meet the propagation conditions of whistle mode in the weak magnetized plasma sheath.And the transmittance of whistle mode is less affected by the variation of the electron density and the collision frequency.It can be used as a communication window.展开更多
A variational principle code which can calculate self-consistently currents on the conductors is used to assess the coupling characteristic of the EAST 4-strap ion cyclotron range of frequency（ICRF） antenna. Taking ...A variational principle code which can calculate self-consistently currents on the conductors is used to assess the coupling characteristic of the EAST 4-strap ion cyclotron range of frequency（ICRF） antenna. Taking into account two layers of antenna conductors without lateral frame but with slab geometry, the antenna impedances as a function of frequency and the structure of RF field excited inside the plasma in various phasing cases are discussed in this paper.展开更多
Energy dissipation and power deposition of electromagnetic waves(EMW)in the reentry plasma sheath provide an opportunity to investigate‘communication blackout’phenomena.Based on afinite element method(FEM)simulation...Energy dissipation and power deposition of electromagnetic waves(EMW)in the reentry plasma sheath provide an opportunity to investigate‘communication blackout’phenomena.Based on afinite element method(FEM)simulation,we analyze variation of EMW energy dissipation and power deposition profiles dependent on the wave polarization,wave incident angle,plasma density profile and electron collision frequency.Cutoff and resonance of EMW in the plasma sheath are crucial in explaining the regulation of energy dissipation and power deposition.展开更多
In this work,microwaves and terahertz waves have performed a dual-frequency combineddiagnosis in high-temperature,large-scale plasma.According to the attenuation and phase shift of electromagnetic waves in the plasma,...In this work,microwaves and terahertz waves have performed a dual-frequency combineddiagnosis in high-temperature,large-scale plasma.According to the attenuation and phase shift of electromagnetic waves in the plasma,the electron density and collision frequency of theplasma can be inversely calculated.However,when the plasma size is large and the electron density is high,the phase shift of the electromagnetic wave is large(multiple times 2πperiod).Due to the limitations of the test equipment,the true phase shift is difficult to test accurately or to recover reality.That is,there is a problem of phase integer ambiguity.In order to obtain a phase shift of less than 180°,a higher electromagnetic wave frequency(terahertz wave with 890 GHz)is used for diagnosis.However,the attenuation of the terahertz wave diagnosis is too small(less than 0.1 d B),only the electron density can be obtained,and the collision frequency cannot be accurately obtained.Therefore,a combined diagnosis was carried out by combining twofrequencies(microwave with 36 GHz,terahertz wave with 890 GHz)to obtain electron density and collision frequency.The diagnosis result shows that the electron density is in the range of(0.65–1.5)×1019m^(-3),the collision frequency is in the range of 0.65–2 GHz,and the diagnostic accuracy is about 60%.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.12275202,62371372,62101406,and 62001340)China Postdoctoral Science Foundation(Grant Nos.2022M71490 and 2020M673341)+1 种基金the Innovation Capability Support Program of Shaanxi Province,China(Grant No.2022TD-37)the Natural Science Basic Research Program of Shaanxi Province,China(Grant No.2023JC-YB-549)。
文摘“Magnetic window”is considered as an effective method to solve the communication blackout issue.COMSOL software package based on the finite element method is utilized to simulate the propagation of right-handed circularly polarized wave in the magnetized plasma sheath.We assume a double Gaussian model of electron density and an exponential attenuation model of magnetic field.The propagation characteristics of right-handed circularly polarized wave are analyzed by the observation of the reflected,transmitted and loss coefficient.The numerical results show that the propagation of right-handed circularly polarized wave in the magnetized plasma sheath varies for different incident angles,collision frequencies,non-uniform magnetic fields and non-uniform plasma densities.We notice that reducing the wave frequency can meet the propagation conditions of whistle mode in the weak magnetized plasma sheath.And the transmittance of whistle mode is less affected by the variation of the electron density and the collision frequency.It can be used as a communication window.
基金supported by the National Magnetic Confinement Fusion Science Program,China(Grant No.2015GB101001)the National Natural Science Foundation of China(Grant Nos.11375236 and 11375235)
文摘A variational principle code which can calculate self-consistently currents on the conductors is used to assess the coupling characteristic of the EAST 4-strap ion cyclotron range of frequency（ICRF） antenna. Taking into account two layers of antenna conductors without lateral frame but with slab geometry, the antenna impedances as a function of frequency and the structure of RF field excited inside the plasma in various phasing cases are discussed in this paper.
基金funded by National Natural Science Foundation of China(Nos.61627901 and 61871302)the Shaanxi National Natural Science Foundation under Grant No.2019JZ-15
文摘Energy dissipation and power deposition of electromagnetic waves(EMW)in the reentry plasma sheath provide an opportunity to investigate‘communication blackout’phenomena.Based on afinite element method(FEM)simulation,we analyze variation of EMW energy dissipation and power deposition profiles dependent on the wave polarization,wave incident angle,plasma density profile and electron collision frequency.Cutoff and resonance of EMW in the plasma sheath are crucial in explaining the regulation of energy dissipation and power deposition.
基金supported in part by National Natural Science Foundation of China(Nos.61627901,61601353,61801343 and 61901321)。
文摘In this work,microwaves and terahertz waves have performed a dual-frequency combineddiagnosis in high-temperature,large-scale plasma.According to the attenuation and phase shift of electromagnetic waves in the plasma,the electron density and collision frequency of theplasma can be inversely calculated.However,when the plasma size is large and the electron density is high,the phase shift of the electromagnetic wave is large(multiple times 2πperiod).Due to the limitations of the test equipment,the true phase shift is difficult to test accurately or to recover reality.That is,there is a problem of phase integer ambiguity.In order to obtain a phase shift of less than 180°,a higher electromagnetic wave frequency(terahertz wave with 890 GHz)is used for diagnosis.However,the attenuation of the terahertz wave diagnosis is too small(less than 0.1 d B),only the electron density can be obtained,and the collision frequency cannot be accurately obtained.Therefore,a combined diagnosis was carried out by combining twofrequencies(microwave with 36 GHz,terahertz wave with 890 GHz)to obtain electron density and collision frequency.The diagnosis result shows that the electron density is in the range of(0.65–1.5)×1019m^(-3),the collision frequency is in the range of 0.65–2 GHz,and the diagnostic accuracy is about 60%.
