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首页> 外文学位 >The measurement of absolute helium ion density profiles on the DIII-D tokamak using charge exchange recombination spectroscopy.
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The measurement of absolute helium ion density profiles on the DIII-D tokamak using charge exchange recombination spectroscopy.

机译：使用电荷交换复合光谱仪在DIII-D托卡马克上测量绝对氦离子密度分布。

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摘要

In future burning fusion devices, helium will be an unavoidable impurity component of the plasma. The overall performance of such devices is critically dependent on the helium transport properties of the confined plasma. Poor helium transport in reactors could lead to a buildup of fusion ash, causing fuel dilution and increased radiation that will result in degraded fusion power and possibly quench ignition altogether. As a result, it is essential to investigate the helium transport and exhaust properties of tokamak plasmas in order to design an optimized helium removal system for future reactors. These studies require accurate spatial and temporal measurements of the helium density profiles in tokamak plasmas.;The purpose of this work has been to instrument and calibrate the existing charge-exchange recombination (CER) spectroscopy diagnostic used to measure the ion temperature and plasma rotation speeds on the DIII-D tokamak for the simultaneous measurement of absolute helium density profiles as well. This has involved (1) absolutely calibrating the CER system using standard calibration lamps and two novel techniques involving neutral beam injection into a gas filled torus and a pure He plasma, (2) developing and testing a neutral beam attenuation code to calculate the local neutral beam density at each viewing location, (3) assembling a database of accurate atomic data, (4) analyzing the measured CER spectra with a multi-Gaussian fitting procedure, and (5) developing and testing a modeling code that distinguishes unwanted signal contributions from drifting hydrogen-like helium ions (the 'plume effect').;Absolute helium density profiles have been measured for a variety of tokamak operating conditions, including low confinement (L-mode) and high confinement (H-mode) discharges. Helium transport behavior has been observed by injecting helium gas puffs into DIII-D plasmas and measuring the He density profile evolution. The measured profiles are found to have a similar shape as the measured electron density profiles, thereby disputing the unfavorable prediction by neo-classical transport theory that there is preferential accumulation of helium in the plasma center. The effective use of edge-localized modes (ELMs) to purge helium from H-mode discharges has also been observed.
机译：在未来的燃烧聚变设备中，氦将成为等离子体中不可避免的杂质成分。这种装置的整体性能主要取决于受限等离子体的氦气传输特性。反应堆中氦气传输不良可能导致聚变灰堆积，导致燃料稀释和辐射增加，这将导致聚变能力下降并可能完全熄灭点火。因此，必须研究托卡马克等离子体的氦气传输和排气特性，以便为未来的反应堆设计优化的氦气去除系统。这些研究需要对托卡马克等离子体中的氦气密度分布进行准确的时空测量;这项工作的目的是仪器和校准用于测量离子温度和等离子体旋转速度的现有电荷交换复合（CER）光谱诊断在DIII-D托卡马克上也可以同时测量绝对氦气密度曲线。这涉及（1）使用标准校准灯对CER系统进行绝对校准，以及两项涉及将中性束注入到充气圆环和纯He等离子体中的新颖技术，（2）开发和测试中性束衰减码以计算局部中性每个观察位置的电子束密度；（3）组装一个准确的原子数据的数据库；（4）使用多高斯拟合程序分析测得的CER光谱；（5）开发和测试区分非所需信号贡献的建模代码漂移的氢样氦离子（“泡沫效应”）。在多种托卡马克操作条件下（包括低限制（L模式）和高限制（H模式）放电）已测量了绝对氦密度分布。通过将氦气吹入DIII-D等离子体并测量He密度分布演变，可以观察到氦气的传输行为。发现所测量的轮廓具有与所测量的电子密度轮廓相似的形状，从而驳斥了新古典传输理论的不利预测，即等离子体中心中存在氦的优先积累。还观察到有效利用边缘局限模式（ELM）从H模式放电中清除氦气。

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  • 作者

    Finkenthal, Daniel Franklin.;

  • 作者单位

    University of California, Berkeley.;

  • 授予单位 University of California, Berkeley.;
  • 学科 Engineering Nuclear.;Physics Fluid and Plasma.
  • 学位 Ph.D.
  • 年度 1994
  • 页码 274 p.
  • 总页数 274
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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