MECHANISM FOR GENERATION AND RELAXATION OF DISRUPTIONS BASED ON NAMOLAOUS TRANSPORT

本研究旨在对环形等离子体中的各种扰动现象有一个基本的认识。我们提出了反常输运与等离子体不稳定性之间的非线性联系的新机制。结果表明，如果满足色散条件，电子粘性就会大大增加，从而导致不稳定辉光率的增加。作为这种耦合的结果，在微扰幅度超过磁随机性的阈值条件的情况下，发生等离子体形变的爆炸性爆发。如果形变变得太大，导致离子粘度增加，则模式生长被禁止。这些机制解释了破裂的突然发生，似乎与电阻率无关的快速增长，以及破坏的突然终止。这种方法被扩展到等离子体中的微观波动。研究发现，等离子体湍流可以引起涨落的增长：定态是由非线性失稳(通过驻极子粘性)和非线性稳定化(通过离子粘性和热扩散率)之间的平衡实现的。与传统的拟线性湍流图景相比，这一理论框架在输运理论方面取得了质的进展。这一“自持节流”理论所给出的输运系数似乎解释了环形等离子体中L模和改进的限制模的各种特征。

This research aims to provide a basic understanding for the various disruptive phenomena in toroidal plasmas. We propose a new mechanism of the nonlinear link between the anomalous transport and the plasma instabilities. It is found that the electron viscosity, which is enhanced much if the stachasticity condition is satisfied, can cause the increment in the instability glowth rate. As a result of this coupling, an explosive burst of the plasma deformation occurs, in the case that the perturbation amplitude exceeds a threshold condition for the magnetic stochasticity. If the deformation becomes so large that the ion viscosity is enhanced, then the mode growth is prohibited. These mechanisms explain an abrupt occurence of the disruption, rapid growth which seems to be independent of the resistivity, and the sudden termination of the destruction.This methodology is extended to the microscopic fluctuations in the plasma. It is found that the plasma turbulence can causes the growth of fluctuations : The stationary state is realized by the ballance between the nonlinear destabilization (via electreon viscosity) and the nonlinear stabilization (through ion viscosity and thermal diffusivity). This theoretical framwork gives a qualitative advancement in the transport theory in comparison with the conventional quasi-linear picture of turbulence. The transport coefficient, which is given by this'Self-sustained Thrbulence'theory, seems to explain various features in the L-mode and improved confinement modes in toroidal plasmas.