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论文类型：期刊论文

发表时间：2017-12-01

发表刊物：PHYSICS OF PLASMAS

收录刊物：SCIE、EI

卷号：24

期号：12

ISSN号：1070-664X

摘要：The dynamic structure evolution of intense ion beams with a large edge density gradient is investigated in detail with an analytical model and two-dimensional particle-in-cell (PIC) simulations, with special attention paid to the influence of beam radius. At the initial stage of beam-plasma interactions, the ring structure is formed due to the transverse focusing magnetic field induced by the unneutralized beam current in the beam edge region. As the beam-plasma system evolves self-consistently, a second ring structure appears in the case of ion beams with a radius much larger than the plasma skin depth, due to the polarity change in the transverse magnetic field in the central regions compared with the outer, focusing field. Influences of the current-filamentation and two-stream instability on the ring structure can be clearly observed in PIC simulations by constructing two different simulation planes. Published by AIP Publishing.