Question

24 pts. Phase and group velocity of a plasma. The permittivity ε of a plasma (ionized gas) is a function of frequency given by: I. Eo where co is radian frequency and o the "plasma frequency", which is assumed to be a constant related to the properties of the ionized gas. (a) 6 pts. Given the relation above, write an expression for the phase velocity in a plasma. (Assume μ-,-1). (b) 2 pts. Write an expression for the magnitude of the wavenumber k of an EM wave propagating in the plasma (c) 8 pts. Derive an expression for group velocity of the plasma (d) 4 pts. Is the phase or group velocity in the plasma larger than c (the speed of light in a vacuum)? Is this a problem? (e) 4 pts. What happens to waves with radian frequency ω < (op that enter this medium?

Answer 1

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