Langmuir waves dispersion relation

AI Thread Summary
The discussion centers on the dispersion relation for Langmuir waves in plasma, highlighting an expression that includes an additional imaginary term. This term is believed to arise from the full derivation of the dispersion relation for warm electrons. The question posed is whether a purely imaginary term can have physical significance, as it is typically associated with phase rather than physical quantities. The conversation explores the mathematical implications of imaginary numbers, noting their role in representing wave phases and the necessity of both real and imaginary components to reconstruct the original wave. The significance of the imaginary term in the context of plasma physics remains a point of inquiry.
ian2012
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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?
 
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Typically imaginary numbers deal with phases
 
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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