有限長イオンビーム・プラズマ系における不安定低周波

概要

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One dimensional fluid equations are examined together with Poissons equation for an ion beam plasma system by taking the boundary condition into account, as was done by Pierce for an electron beam. An ion acoustic wave and a slow wave of the beam under such a condition become unstable even if they are stable in an unbounded case. The wave split into many unstable new modes for given parameters of the system. Their frequencies as well as the growth rates depend largely on the length L of the system, the drift velocity Vo of the ion beam and the electron thermal velocity. The frequencies decrease monotonously with increasing the value of ωpi L/Vo. Meanwhile, the growth rates appear suddenly at certain values of ωpiL/Vo, and they attain to their maximum values at respective different ones and then they decrease gradualy. Each maximum growth rate is greater than the other growth rates for the same value of ωpiL/Vo. Theoretical results are compared with the experimental ones, which gives qualitative agreement.
社団法人プラズマ・核融合学会の論文