Theoretical and experimental studies of electromagnetic wave transmission in plasma

Abstract

The aircrafts, such as space shuttle, spaceship and so on, are facing the well-known blackout problem when they reentry into the atmosphere. The plasma sheath leads electromagnetic waves to attenuation, and the communications between the aircrafts and the ground to losing, and even completely interrupte, thereby resulting in the loss of radar targets and threatening the lives of the astronauts. Therefore, it is important to study the properties of the electromagnetic wave transmission in plasma. The characteristics of electromagnetic wave transmission in plasma are studied theoretically and experimentally in this paper. The variations of the electromagnetic wave attenuation with plasma density, collision frequency and electromagnetic wave frequency are obtained. The electromagnetic wave attenuation increasean an order of magnitude with plasma density increasing an order of magnitude. The electromagnetic wave attenuation first increases and then decreases with plasma collision frequency increasing, the electromagnetic wave attenuation decreases with the increase of electromagnetic wave frequency. The electromagnetic wave transmission properties in plasma are studied experimentally with shock tube, and the experimental results accord well with the theoretical results. The results show that increasing the electromagnetic wave frequency is an effective way to solve the reentry blackout problem.

In-situ electron density measurement in inductively coupled plasma using microwave reflectometer by Wi-Fi antenna on wafer

“…In addition, the amplitude of attenuation increased as the RF power increased, which is related to the physical phenomenon resulting from the plasma permittivity ε p , defined as ε p = 1 − ωp ω 2 −jων , where ν denotes the plasma collision frequency. The wave number k of the microwaves propagating inside the plasma can be defined by an equation relating to the plasma permittivity ε p : k = k 0 ε 1/2 p = β + jα, where k 0 is the wave number of microwaves in free space, real β corresponds to the phase constant, and the imaginary number α represents the attenuation constant [24][25][26]. The attenuation of microwaves in the plasma is related to the attenuation constant α.…”

Controllable Enhancement of Evanescent and Transmitted Waves by a Plasma Sphere

“…According to Eq. 3, the plasma permittivity depends on the incident frequency f i , the plasma frequency f p , and the collision frequency ] c [26]. The influences of different collision frequencies and plasma frequencies on the plasma permittivity are exemplified with f i 4 GHz in Figure 1.…”

Microwave propagation with the gas breakdown

“…If the microwave propagates in a space-and timeindependent plasma, then the electric field damping is given by [16]…”

“…On the other hand, the effect of time-independent plasmas on microwave propagation has also been studied by some scholars. [16][17][18][19][20][21][22][23] However, in microwave breakdown, the plasmas do not preexist but they grow over time owing to the ionization breakdown. Some scholars adopt the finite-difference time-domain method [24,25] to simulate the self-consistent interaction between the microwave propagation and the breakdown.…”