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Langmuir waves dispersion relation

  1. May 24, 2010 #1
    I was just looking at an expression (a dispersion relation, omega^2 = ...) similar to that of warm electron's in a plasma http://en.wikipedia.org/wiki/Plasma_oscillation expect with an extra imaginary term, which I think comes out from the full derivation of the dispersion relation for warm electrons. I am guessing the relation that everybody knows of is then the Real part of the expression I was looking at.
    My question is, can a purely imaginary term have some physical significance? Surely it isn't physical?
  2. jcsd
  3. May 24, 2010 #2
    Typically imaginary numbers deal with phases
  4. May 26, 2010 #3
    Mathematically, you can split a single-valued wave of arbitrary phase for each frequency component it contains into 2 components where the difference in phase of each frequency is 90 degrees. The more phase advanced of the 2 is called real while the least advanced is called imaginary. Both are necessary to reconstruct the original wave.
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