• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文学位 >Models and physics of plasma wakefield accelerators in beam-ionized gases.
【24h】

Models and physics of plasma wakefield accelerators in beam-ionized gases.

机译：束流电离气体中等离子体尾流加速器的模型和物理学。

获取原文
获取原文并翻译 | 示例
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

Plasma-based accelerators have attracted great attention recently for their high accelerating gradients. One of the leading plasma accelerator schemes is the plasma wakefield accelerator (PWFA), in which an intense relativistic electron or positron beam propagates in pre-ionized plasma and creates plasma waves. Most of the previous theories and experiments are concerned wakes created in pre-ionized plasmas. The work presented in this dissertation investigates the propagation of a high-energy electron beam through a gas that is self-consistently ionized by the beam's space charge. As shorter and shorter high-density beams are used in current experiments to get higher accelerating fields, the self-fields of these beams can ionize neutral gases or further ionize a plasma. This beam ionization can provide a new way of creating plasma sources for plasma wakefield accelerators or after the wakes in pre-formed PWFAs. The wake generation in self-ionized plasma is explored through 2-D and 3-D particle-in-cell (PIC) simulations. New physics phenomena such as ionization hosing in self-ionized plasma are found and studied analytically and with 3-D PIC simulations.; The implementation of 2-D and 3-D impact and field ionization models in the particle-in-cell code OSIRIS is introduced. The new OSIRIS model is then used to find the optimal gas density for maximizing the plasma wakefield in a self-ionized plasma. Simulation results and physical explanations are given.; Different gas types, beam parameters and gas densities are studied to support the design and analysis of current E-164 and E-164X PWFA experiments at the Stanford Linear Accelerator Center (SLAC). Simulations are performed for actual experimental conditions and the effects of experimental realities such as tilted and asymmetric beams and inhomogeneous plasmas are investigated. The simulations support the interpretation of the results in E-164 and E-164X. Excellent agreement between the energy gain observed in experiments and the simulations is obtained (only) when ionization and realistic gas profiles are included.; A new instability mechanism is observed and studied analytically and with simulations. The instability arises from the coupling between a beam and the offset plasma channel it creates when it is perturbed slightly from a straight path. The coupling can either add to the traditional electron hose instability in a pre-formed or replace it with a much slower growth depending on the radius of the ionization channel compared to the distance that electrons are blown outward by the beam space charge. (Abstract shortened by UMI.)
机译：基于等离子体的加速器最近因其高加速梯度而备受关注。领先的等离子加速器方案之一是等离子唤醒场加速器（PWFA），其中强相对论电子或正电子束在预电离的等离子中传播并产生等离子波。先前的大多数理论和实验都与预电离等离子体中产生的尾波有关。本文研究的是高能电子束通过气体的传播，该气体由电子束的空间电荷自洽地电离。由于当前实验中使用越来越短的高密度束来获得更高的加速场，这些束的自场可以使中性气体电离或使等离子体进一步电离。这种束电离可以提供一种新的方式来创建等离子流场加速器的等离子体源，也可以在预成型的PWFA中唤醒后产生等离子体源。通过2-D和3-D单元内粒子（PIC）仿真，探索了自电离等离子体中的唤醒产生。发现并通过3-D PIC仿真分析并研究了新的物理现象，例如自电离等离子体中的电离软管。介绍了2-D和3-D碰撞和场电离模型在单元格代码OSIRIS中的实现。然后，使用新的OSIRIS模型查找最佳气体密度，以使自电离等离子体中的等离子体尾流场最大化。给出了仿真结果和物理解释。在斯坦福线性加速器中心（SLAC），研究了不同的气体类型，束参数和气体密度，以支持当前E-164和E-164X PWFA实验的设计和分析。针对实际实验条件进行了仿真，并研究了诸如倾斜光束和非对称光束以及不均匀等离子体等实验现实的影响。仿真支持对E-164和E-164X中的结果进行解释。 （仅）当包括电离和实际气体分布时，才能获得在实验和模拟中观察到的能量增益之间的极佳一致性。观察到了一种新的不稳定机制，并进行了分析和仿真研究。当光束与直线路径发生轻微扰动时，光束与偏置等离子体通道之间的耦合会导致不稳定。与电子束的束流电荷向外吹出的距离相比，这种耦合既可以增加预成型的传统电子软管的不稳定性，也可以用慢得多的增长速度来取代它，具体取决于电离通道的半径。 （摘要由UMI缩短。）

著录项

  • 作者

    Deng, Suzhi.;

  • 作者单位

    University of Southern California.;

  • 授予单位 University of Southern California.;
  • 学科 Engineering General.; Physics Fluid and Plasma.
  • 学位 Ph.D.
  • 年度 2005
  • 页码 166 p.
  • 总页数 166
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 工程基础科学;等离子体物理学;
  • 关键词

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号