جستجوی مقالات مرتبط با کلیدواژه "plasma with varying density" در نشریات گروه "فیزیک"

In this paper, a theoretical study of electromagnetic wave passing through inhomogeneous over-dense plasma was performed. It was supposed that the plasma layer is immersed in vacuum and the plasma density has aparabolic profileform. In this way, the electric permittivity profile decreases gradually, acquires negative values, and then again becomes positive on the other side of the slab. It has been shown that how this structure is suitable for the transmission of electromagnetic waves in a wide range of the incident angle.To this end, the normal mode and the oblique incident was considered. Then the amplitude of the electromagnetic waves and the reflection coefficient were analytically and exactly calculated and discussed. Dependence of the coefficient of the entire structure to the parameters influencing the problem was evaluated.

An investigation isundertaken to study the transmission of the electromagnetic waves through inhomogeneous over-dense plasma. The transmission is due to the excitation of the surface modes of plasma or plasmons. The construction of the plasma is in such a way that the charge density of the plasma linearly increases and passes through its critical value and then linearly decreases. The dissipative effects are considered for the plasma. The amplitude of the electromagnetic waves and the reflection coefficient are calculated and then the distribution of the electric field amplitude of the entire structure is obtained and discussed. In this way، itis shown that the considered structure facilitates the anomalous wave transmission through over-dense plasma medium.

Here، the transmission of electromagnetic waves was studied through an inhomogeneous over-dense plasma medium in the presence of a magnetic field. This plasma medium is in fact a kind of left handed material (LHM)، in which the excitation of the surface waves is the principle actor for the transmission of electromagnetic waves. A specific structure was introduced for the overdense plasma and results showed that the surface waves can effectively be excited on both sides of the structure. The charge density of the plasma layer is supposed to have spatial variation، and in such a way that the density gradually (linearly) increases from both sides of the slab. In this way، the generalized electric permittivity of the plasma structure linearly acquires negative values and then، with the same rate، becomes positive. It is only considered the normal mode of the system. The amplitude of the electromagnetic waves was studied for the total structure، in the normal mode، for the perpendicular and oblique incidences. It was found that in this mode the surface waves can be excited effectively at the plasma surface، and hence the introduced structure has the capability of being used as a super lens.