The phase velocity of an ion acoustic wave propagating in a collisionless plasma is observed to decrease with wave amplitude at the same frequency. The nonlinear shift in the wavenumber is found to be proportional to the square root of the initial wave amplitude, showing the effects of trapped ions. The observed results are in good agreement with nonlinear theory provided by analogy with an electron plasma wave.
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© 1976 American Institute of Physics.
1976
American Institute of Physics
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