Oscillating two-stream instability of a plasma wave in a plasmachannel |
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Authors: | Ramachandran K. Tripathi V.K. |
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Affiliation: | Dept. of Phys., Indian Inst. of Technol., Delhi ; |
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Abstract: | A long wavelength Langmuir wave (ω0, k0), propagating through a parabolic plasma density channel, can decay into a low-frequency mode (ω,k&oarr;) and two short wavelength Langmuir wave sidebands (ν1,2,k&oarr;1,2 ), via two-stream instability where ω1,2=ω∓ω0 and k&oarr;1,2=k&oarr;∓k&oarr;0. Depending on the mode number n, the growth rate maximizes in the range γmax≃0.1ωpi-0.4ωpi for the range of k from 0.1(ωpi/cs) to 0.2(ωpi/cx) for ν0~νth where ν0 and νth are the oscillatory and thermal velocities of electrons, ωpi is the ion plasma frequency on the axis, and cs is the sound speed. The growth rate increases with the width a of the plasma density channel. It decreases with the mode number. The instability may be relevant to laser based charged particle accelerators |
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