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Electromagnetic Torque in Tokamaks with Toroidal Asymmetries.

机译：托卡马克具有环形不对称性的电磁转矩。

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摘要

Toroidal rotation and rotation shear strongly influences stability and confinement in tokamaks. Breaking of the toroidal symmetry by fields orders of magnitude smaller than the axisymmetric field can, however, produce electromagnetic torques that significantly affect the plasma rotation, stability and confinement. These electromagnetic torques are the study of this thesis.;There are two typical types of electromagnetic torques in tokamaks: 1) "resonant torques" for which a plasma current defined by a single toroidal and single poloidal harmonic interact with external currents and 2) "nonresonant torques" for which the global plasma response to nonaxisymmetric fields is phase shifted by kinetic effects that drive the rotation towards a neoclassical offset. This work describes the diagnostics and analysis necessary to evaluate the torque by measuring the rate of momentum transfer per unit area in the vacuum region between the plasma and external currents using localized magnetic sensors to measure the Maxwell stress. These measurements provide model independent quantification of both the resonant and nonresonant electromagnetic torques, enabling direct verification of theoretical models.;Measured values of the nonresonant torque are shown to agree well with the perturbed equilibrium nonambipolar transport (PENT) code calculation of torque from cross field transport in nonaxisymmetric equilibria. A combined neoclassical toroidal viscosity (NTV) theory, valid across a wide range of kinetic regimes, is fully implemented for the first time in general aspect ratio and shaped plasmas. The code captures pitch angle resonances, reproducing previously inaccessible collisionality limits in the model. The complete treatment of the model enables benchmarking to the hybrid kinetic MHD stability codes MARS-K and MISK, confirming the energy-torque equivalency principle in perturbed equilibria. Experimental validations of PENT results confirm the torque applied by nonaxisymmetric coils is often proportional to the energy put into the dominant ideal MHD kink mode. This reduces the control of nonresonant torque to a single mode model, enabling efficient feed forward optimization of applied fields. Initial results including the anisotropic kinetic pressure tensor directly in the plasma eigenmode calculations are presented here, and may eventually provide accurate metrics for multimodal coupling similar to the established single mode metrics.
机译：环形旋转和旋转剪切力强烈影响托卡马克的稳定性和限制。但是，通过比轴对称场小几个数量级的场来破坏环形对称性，可能会产生电磁转矩，从而显着影响等离子体的旋转，稳定性和限制。这些电磁转矩是本论文的研究。；托卡马克中有两种典型的电磁转矩类型：1）“谐振转矩”，由单个环形和单个多极谐波定义的等离子体电流与外部电流相互作用； 2）“ “非共振转矩”，其对非轴对称场的整体等离子体响应通过驱动旋转朝向新古典偏移的动力学效应而发生相移。这项工作描述了通过使用局部磁传感器测量麦克斯韦应力来测量等离子体和外部电流之间在真空区域中每单位面积的动量传递速率来评估扭矩所需的诊断和分析。这些测量提供了谐振和非谐振电磁转矩的模型独立量化，从而可以直接验证理论模型。非谐振转矩的测量值显示出与扰动平衡非极性移动（PENT）代码的交叉场转矩计算非常吻合在非轴对称平衡中运输。结合新古典环形粘度（NTV）理论，在广泛的动力学范围内有效，首次在一般纵横比和成形等离子体中得到了全面实现。该代码捕获俯仰角共振，从而重现模型中以前无法访问的碰撞极限。该模型的完整处理使得可以对混合动力学MHD稳定性代码MARS-K和MISK进行基准测试，从而确定了扰动平衡中的能量-扭矩等效原理。 PENT结果的实验​​验证证实了非轴对称线圈施加的扭矩通常与占主导地位的理想MHD扭结模式的能量成比例。这将非共振转矩的控制减少到单模模型，从而实现了对应用领域的高效前馈优化。这里介绍了直接在等离子体本征模式计算中包括各向异性动压张量的初始结果，并且最终可能为多峰耦合提供类似于已建立的单模度量的准确度量。

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  • 作者

    Logan, Nikolas Christopher.;

  • 作者单位

    Princeton University.;

  • 授予单位 Princeton University.;
  • 学科 Physics Fluid and Plasma.
  • 学位 Ph.D.
  • 年度 2015
  • 页码 229 p.
  • 总页数 229
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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