Effects of Nonuniform Magnetic Fields on the “Magnetic Window” in Blackout Mitigation

The “magnetic window” is considered a promising means to eliminate reentry communications blackout. Nevertheless, a numerical analysis is needed detailing the efficacy of the window under nonuniform magnetic fields generated by a magnet. For this purpose, the electromagnetic wave transmission characteristics are obtained using the hybrid matrix method. A two-Gaussian model for the plasma sheath density is assumed. The sheath is modeled by partitioning into slabs, for which the magnetic field and electron density in each slab are assumed uniform. Various plasma parameter values and magnetic field strengths are used. The numerical results show that, compared with uniform magnetic fields, a wider stopband in the transmission response is formed using nonuniform magnetic fields; the stopband width depends on the range between the maximum and the minimum magnetic field strengths. Therefore, the frequency hoped for in the magnetic window in the left passband using uniform magnetic field may be located in the stopband arising from the nonuniform magnetic field.