Abstract
A hypersonic flight or a reentry vehicle is surrounded by a plasma layer that prevents electromagnetic wave transmission, which results in radio blackout. The magnetic-window method is considered a promising means to mitigate reentry communication blackout. However, the real application of this method is limited because of the need for strong magnetic fields. To reduce the required magnetic field strength, a novel method that applies a traveling magnetic field (TMF) is proposed in this study. A mathematical model based on magneto-hydrodynamic theory is adopted to analyze the effect of TMF on plasma. The mitigating effects of the TMF on the blackout of typical frequency bands, including L-, S-, and C-bands, are demonstrated. Results indicate that a significant reduction of plasma density occurs in the magnetic-window region by applying a TMF, and the reduction ratio is positively correlated with the velocity of the TMF. The required traveling velocities for eliminating the blackout of the Global Positioning System (GPS) and the typical telemetry system are also discussed. Compared with the constant magnetic-window method, the TMF method needs lower magnetic field strength and is easier to realize in the engineering field.
Highlights
Hypersonic flight and spacecraft reentry are associated with the appearance of shock waves in front of the vehicle, converting much of the vehicle’s kinetic energy into heat and increasing the air temperature
An experimental test to measure the effects of a magnetic field on Very High Frequency (VHF) waves propagation in plasma layer was carried out in the 1960s,10 and the results indicated that the signal attenuation is reduced from 45 dB for zero-field to 28 dB at a 0.75 T magnetic field
Attenuation of the EM wave can be reduced by applying traveling magnetic field (TMF), and the blackout caused by a lower plasma density requires a lower traveling velocity for mitigation
Summary
Hypersonic flight and spacecraft reentry are associated with the appearance of shock waves in front of the vehicle, converting much of the vehicle’s kinetic energy into heat and increasing the air temperature. To reduce sheath thickness, the reentry vehicle must be as sharply pointed as possible, which reduces the payload capacity and increases the aerodynamic heating of the vehicle.[2] High transmission power creates an electrical breakdown of the atmosphere, further ionizing the air and contributing to the original problem.[3] we should develop a reliable and effective mitigation scheme for communication through the plasma layer. Considerable effort has been exerted toward addressing the problem associated with decreasing the required magnetic field.[16,17,18,19,20,21] An electromagnetic E×B layer approach was proposed for this problem and analyzed by a magneto-hydrodynamic model.[16] Simulation results showed that the application crosses electric and magnetic fields, reduces the plasma density near the antenna, and enables radio communication across the plasma.
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