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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. ==Cut-off frequency and critical density== In an unmagnetized plasma in the high frequency or low density limit, i.e. for or , the wave speed is the speed of light in vacuum. As the density increases, the phase velocity increases and the group velocity decreases until the cut-off frequency where the light frequency is equal to the plasma frequency. 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. In a magnetized plasma, except for the O wave, the cut-off relationships are more complex. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Electromagnetic electron wave」の詳細全文を読む スポンサード リンク
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