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

Abstract

We propose a method of applying a static magnetic field to reduce the attenuation of the magnetic field component (S H) of low-frequency electromagnetic (LF EM) waves in dense plasma. The principle of this method is to apply a static magnetic field to limit electron movement, thereby increasing the equivalent resistance and thus reducing the induced current and S H. We consider the static magnetic field acting on the plasma of the entire induced current loop rather than on the local plasma, where the induced current is excited by the magnetic field component of LF EM waves. Analytical expressions of S H suitable for magnetized cylindrical enveloping plasma are derived by adopting an equivalent circuit approach, by which S H is calculated with respect to various plasma parameter settings. The results show that S H can be reduced under a static magnetic field and the maximum magnetic field strength that mitigates blackout is less than 0.1 T. Experiments in which LF EM waves propagate in a shock-tube-generated magnetized cylindrical enveloping plasma are also conducted. S H measured under the magnetic field (the magnetic field strength B 0 acting on the magnetic field probe was about 0.06 T) reduces at f = 10 MHz and f = 30 MHz when n e ≈ 1.9 × 1013 cm−3, which is consistent with theoretical results. The verification of the theory thus suggests that applying a static magnetic field with a weak magnetic field has the potential to improve the transmission capacity of LF EM waves in dense plasma.