Investigation On The Microwave Absorption Properties Of Nonuniform Hydrogen Plasma In Carbon Nanotubes Films

Modern military stealth and microwave protection put forward higher requirements on the microwave absorbing materials. Carbon nanotubes and their compound material have received worldwide attention due to their novel structures, low specific mass and excellent mechanical, thermal, electrical, magnetic, optical properties. The structural characterizations of carbon nanotubes provide advantageous condition for the adsorption of hydrogen gas. Under microwave interaction, hydrogen can form plasma. The experimental data show that hydrogen plasma in carbon nanotubes films is the most valuable microwave absorbing material.Our group has investigated the microwave absorption properties of uniform hydrogen plasma in carbon nanotube films. In fact, the density distribution of hydrogen plasma in carbon nanotube films is nonuniform. On the basis of the existing research results, we attempt to make a breakthrough. we study the effects of the plasma density distribution and magnetic field strength on the microwave absorption of hydrogen plasma in carbon nanotube films in detail. Multilayered structure model is proposed for dielectric properties of nonuniform hydrogen plasma in carbon nanotube films. Using the transfer matrix method for solving electromagnetic wave propagation equation, attenuation coefficient formula of microwave in nonuniform of hydrogen plasma in carbon nanotube films is derived. We calculate the microwave absorption coefficients of hydrogen plasma in carbon nanotube films for different magnetic field strength and plasma density distribution.It is shown that plasma density distribution and magnetic field have important roles in microwave responses of hydrogen plasma in carbon nanotubes films. With the increase of the nonuniform degree of the liberal electron in the hydrogen plasma, the maximum absorption attenuation increases obviously and absorption peak shifts towards the high frequencies. With the external magnetic field strength increases, the frequency bandwidth of absorption attenuation exceeding 30.00 d B/cm increases and the absorption peak shifts towards the high frequencies. The numerical results of the microwave attenuation of the film are good agreement with the experimental data. Combining the existing research results, as long as liberal electron density in hydrogen plasma in carbon nanotubes film, the external magnetic field strength and the effective collision frequency of free electron are modestly controlled, strong microwave absorption for specified frequency range can be obtained.The objective of this investigation is to supply theoretical guidance for hydrogen plasma in CNTs applied to both civilian microwave radiation protection and military stealth.