Electromagnetic electron wave

In plasma physics, an electromagnetic electron wave is a wave in a plasma which has a magnetic field component and in which primarily the electrons oscillate. In plasma physics, an electromagnetic electron wave is a wave in a plasma which has a magnetic field component and in which primarily the electrons oscillate. In an unmagnetized plasma, an electromagnetic electron wave is simply a light wave modified by the plasma. In a magnetized plasma, there are two modes perpendicular to the field, the O and X modes, and two modes parallel to the field, the R and L waves. In an unmagnetized plasma for the high frequency or low electron density limit, i.e. for ω ≫ ω p e = ( n e e 2 / m e ϵ 0 ) 1 / 2 {displaystyle omega gg omega _{pe}=(n_{e}e^{2}/m_{e}epsilon _{0})^{1/2}} or n e ≪ m e ω 2 ϵ 0 / e 2 {displaystyle n_{e}ll m_{e}omega ^{2}epsilon _{0},/,e^{2}} where ωpe is the plasma frequency, the wave speed is the speed of light in vacuum. As the electron density increases, the phase velocity increases and the group velocity decreases until the cut-off frequency where the light frequency is equal to ωpe. This density is known as the critical density for the angular frequency ω of that wave and is given by If the critical density is exceeded, the plasma is called over-dense.