Experiment on low-frequency electromagnetic waves propagating in shock-tube-generated magnetized cylindrical enveloping plasma

Guo, Shaoshuai; Xie, Kai; Sun, Bin; Xi, Ruoyao; Liu, Yan

doi:10.1088/2058-6272/abf998

Cited by 8 publications

(4 citation statements)

References 26 publications

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“…In addition, whistle mode at this frequency region facilitates a more expansive propagation region as compared to the capabilities achieved with MHz wave. [24] Moreover, it precludes the necessity for high-frequency THz wave, thereby offering a more pragmatic and simplified approach to antenna design for space vehicles. In summary, low-frequency whistle mode presents a promising avenue for communication owing to its resilience to variations in the defined parameters.…”

Section: Practical Methods For Blackout Mitigationmentioning

confidence: 99%

Characteristics of the electromagnetic wave propagation in magnetized plasma sheath and practical method for blackout mitigation

Wu 吴,

Zhang 张,

Dong 董

et al. 2024

Chinese Phys. B

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“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.

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Section: Practical Methods For Blackout Mitigationmentioning

confidence: 99%

Characteristics of the electromagnetic wave propagation in magnetized plasma sheath and practical method for blackout mitigation

Wu 吴,

Zhang 张,

Dong 董

et al. 2024

Chinese Phys. B

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“…Built-in scaled models in shock tubes are important research tools that have rapidly advanced in the fields of near-space hypersonic aircraft target characteristics, communication interruptions, and plasma flow control. [1][2][3][4][5][6] It is crucial to obtain the electron density and collision frequency distribution of plasma in such work. Over the past decade, the propagation of low-frequency (LF) electromagnetic waves in plasma surrounding a model has attracted much attention.…”

Section: Introductionmentioning

confidence: 99%

Diagnosing ratio of electron density to collision frequency of plasma surrounding scaled model in a shock tube using low-frequency alternating magnetic field phase shift

Wu 吴,

Xie 谢,

Liu 刘

et al. 2024

Chinese Phys. B

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A non-contact low-frequency (LF) method for diagnosing the plasma surrounding a scaled model in a shock tube is proposed. This method utilizes the phase shift occurring after the transmission of an LF alternating magnetic field through the plasma to directly measure of the ratio between the plasma loop average electron density and collision frequency. An equivalent circuit model is used to analyze the relationship between the phase shift of the magnetic field component of LF electromagnetic waves and the plasma electron density and collision frequency. The applicable range of the LF method at a given plasma scale is analyzed. The upper diagnostic limit for the ratio of the electron density (units: m-3) to collision frequency (units: Hz) exceeds 1 × 1011, enabling an electron density exceeding 1 × 1020 m-3 and a collision frequency less than 1 GHz. The paper also assesses the feasibility of using the LF phase shift for plasma diagnosis. Diagnosis experiments were conducted on shock tube equipment using both the electrostatic probe method and LF method. By comparing the diagnostic results of the two methods, the inversion results were relatively consistent, thereby providing preliminary evidence for the feasibility of the LF method. The ratio of the electron density to the collision frequency has a relatively uniform distribution during the plasma stabilization time. The LF diagnostic path is a loop around the model, which is suitable for diagnosing the plasma that surrounds the model. Finally, the causes of diagnostic differences between the two methods are analyzed. The proposed method provides a new avenue for diagnosing high-density enveloping plasma.

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“…The electron density of cylindrical plasma is often nonuniformly distributed. Commonly used methods are numerical calculations, model assumptions, and optimization algorithms to obtain the distribution [29,30]. In order to obtain the distribution of high temperature plasma electron density, a plasma diagnosis method based on microwave diffraction is proposed in this paper.…”

Section: Introductionmentioning

confidence: 99%

Research on plasma electron density distribution based on microwave diffraction

Zhao¹,

Li²,

Liu³

et al. 2022

Plasma Sources Sci. Technol.

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In this paper, a non-contact plasma microwave diffraction measurement method is proposed, which can obtain the electron density at different diameters of the cylindrical plasma. There is a lot of diffraction when a non-focused antenna is used to transmit plasma. As we all know, when the frequency of the incident microwave is lower than the characteristic frequency of the plasma, the microwave cannot be transmitted through the plasma, so this interface can be regarded as a metal. According to the microwave diffraction of the plasma, the size of the plasma correspond-ing to the characteristic frequency can be obtained. Furthermore, by sweeping the incident elec-tromagnetic wave, the size of plasma with different characteristic frequencies can be obtained, and the distribution of electron density can be obtained. To verify the method, a cylindrical plasma was measured by microwave diffraction, in which the electron density of the plasma column gradually decreased along the increase in radius. According to the diffraction of the plasma column at different frequencies, the distribution of the electron density along the diame-ter is obtained. And compared with the transmission diagnosis method, the validity and accuracy of this method are verified. In non-uniform high-temperature plasma, the diffraction method greatly improves the accuracy of spatial diagnosis compared with traditional transmission diag-nosis.

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Experiment on low-frequency electromagnetic waves propagating in shock-tube-generated magnetized cylindrical enveloping plasma

Cited by 8 publications

References 26 publications

Characteristics of the electromagnetic wave propagation in magnetized plasma sheath and practical method for blackout mitigation

Characteristics of the electromagnetic wave propagation in magnetized plasma sheath and practical method for blackout mitigation

Diagnosing ratio of electron density to collision frequency of plasma surrounding scaled model in a shock tube using low-frequency alternating magnetic field phase shift

Research on plasma electron density distribution based on microwave diffraction

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