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Study of the strong electrostatic fields leaved after an interaction between an intense electron beam and plasma

研究强电子束与等离子体相互作用后留下的强静电场

基本信息

批准号：
11680479
负责人：
ANDO Ritoku
金额：
$ 2.37万
依托单位：
Kanazawa University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2000
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-11680479/
关键词：
Langmuir wave strong Langmuir turbulence caviton electron beam probing technique electron beam shadowgraph deflection pattern boiling structure intense relativistic electron beam (IREB)ラングミュア乱流微細構造電子ビームプローブ大強度相対論的電子ビーム IREB 自

项目摘要

Langmuir wave becomes unstable at the large amplitude, and possibly produces a number of localized wave packets of Langmuir wave, which is called a caviton. The nonlinear properties are investigated strongly in the theory of the strong Langmuir turbulent. Generally, measurements of the electric field is difficult, and the 3-dimensional structure of the caviton which is predicted from the theory is not revealed well. The purpose of this research is to study such turbulence field using electron-beam probing-technique. The diagnosis is well known as a method to measure un-known electric field from deflection of the trajectory of a probing beam. Usually a well-focused parallel beam is used for this purpose, and we employed this type of beam for previous experiments. Our study showed difficulties of the method, because the observed deflections could not be attributed only to the caviton fields but other mechanisms. Large ambiguities were left there.At first, the technical problems, that deg … More rade the quality of the data, are solved. It makes possible to detect a probing beam that has much lower density, and raise the reliability of the measurement, and give another possibility. Second, a shadowgraph technique using an electron beam is tried. This is first report to apply the technique for diagnostic. An employment of a large diameter probing-beam makes it possible to detect the special distribution of the deflection. Many bubbles were found in the beam pattern images. It is apparent that a sophisticated field, which is like the one expected from the turbulent theory, exists in our plasma. The averaged size of babbles is change by the plasma density and is estimated about 20 times of the Debye-length in the experiment. On the other side, a theoretical investigation pointed out the fact that the deflection angle becomes prominent only when the cavitons are at final stage of the collapse. It is possible to explain why the small babbles are observed in the experiment, though the turbulent theory says the population of the caviton with larger size is expected to be higher. Less

朗缪尔波在大振幅时变得不稳定，并可能产生许多局域化的朗缪尔波包，称为空穴。在强朗缪尔湍流理论中，对湍流的非线性性质进行了深入的研究。通常，电场的测量是困难的，并且从理论预测的空穴的三维结构没有被很好地揭示。本研究的目的就是利用电子束探测技术来研究这种湍流场。该诊断是众所周知的，作为一种方法来测量未知的电场从偏转的轨迹的探测束。通常使用聚焦良好的平行光束，我们在以前的实验中使用了这种类型的光束。我们的研究表明，该方法的困难，因为观察到的偏转不能只归因于空穴场，但其他机制。在那里留下了很大的含糊之处。起初，技术问题， ...更多信息数据的质量，都解决了。它使得探测密度低得多的探测光束成为可能，提高了测量的可靠性，并提供了另一种可能性。第二，尝试使用电子束的阴影技术。这是首次将该技术应用于诊断。采用大直径的探测梁，可以探测到挠度的特殊分布。在光束图案图像中发现许多气泡。很明显，在我们的等离子体中存在着一个复杂的场，就像湍流理论所预期的那样。在实验中，气泡的平均尺寸随等离子体密度的变化而变化，估计约为Debye长度的20倍。另一方面，理论研究指出，只有在空泡坍缩的最后阶段，偏转角才变得显著。尽管湍流理论认为，尺寸较大的空穴的数量预计会更高，但在实验中观察到小气泡的原因是可能的。少