Aspects of the macroscopic phenomenology of tokamak plasmas - relaxation, transport, and flow generation - are analyzed in the context of phase space dynamics. Particular problems of interest are: i) fluctuation entropy evolution with turbulence driven flows and its application to flow generation by heat flux driven turbulence, and ii) dynamical coupling between phase space structures and zonal flows and its implication for macroscopic relaxation and transport. In chapter 2, intrinsic toroidal rotation drive by heat flux driven turbulence in tokamak is analyzed based on phase space dynamics. In particular, the dynamics of fluctuation entropy with turbulence driven flows is formulated. The entropy budget is utilized to quantify tokamaks as a heat engine system, where heat flux is converted to macroscopic flows. Efficiency of the flow generation process is defined as the ratio of entropy destruction via flow generation to entropy production via heat input. Comparison of the results to experimental scaling is discussed as well. In chapter 3, dynamics of a single phase space structure (drift hole) is discussed for a strongly magnetized 3D plasma. The drift hole is shown to be dynamically coupled to zonal flows by polarization charge scattering. The coupled dynamics of the drift hole and zonal flow is formulated based on momentum budget. As an application, a bound on the self-bound drift hole potential amplitude is derived. The results show that zonal flow damping appears as a controlling parameter. In chapter 4, dynamics of both a single structure and multi- structures in phase space are discussed for a relevant system, i.e. trapped ion driven ion temperature gradient turbulence. The structures are dynamically coupled to zonal flows, since they must scatter polarization charge to satisfy the quasi-neutrality. The coupled evolution of the structures and flows is formulated as a momentum theorem. An implication for transport process is discussed as well. The transport flux is prescribed by dynamical friction exerted by structures on flows. The dynamical friction exerted by zonal flow is a novel effect and reduces transport by algebraically competing against other fluxes, such as a quasilinear diffusive flux

The effects of a uniform horizontal magnetic field on jets dynamics in 2D Boussinesq turbulence, i.e. Howard-Krishnamurti problem are studied with a numerical simulation. For a fixed fluid and magnetic diffusivity, it is shown that as the imposed field strength becomes larger jets start behaving in a more organized way, i.e. achieve stationary state and are finally quenched. The time evolution of total stress, Reynolds stress, Maxwell stress is examined and all the stresses are shown to vanish when jets are quenched. The quenching of jets is confirmed for different values of magnetic diffusivity, albeit the required field strength increases. It is also shown that the inclusion of overstable modes reinforces jets where Maxwell stress overcomes Reynolds stress. For a larger imposed field jets are shown to quench. A possible mechanism for the transition to the reinforcement of jets by Maxwell stress is discussed based on the transition in the most unstable mode in the underlying turbulence.

Abstract Enhancements of edge zonal flows, radial electric fields, and turbulence are observed in electron cyclotron resonance heating-heated plasmas (Zhao et al 2013 Nucl. Fusion 53 083011). In this paper, the effects of sawtooth heat pulses on flows and turbulence are presented. These experiments are performed using multiple Langmuir probe arrays in the edge plasmas of the HL-2A tokamak. The edge zonal flows, radial electric fields, and turbulence are all enhanced by sawteeth. Propagation of the zonal flow and turbulence intensities is also observed. The delay time of the maximal intensity of the electric fields, zonal flows, and turbulence with respect to the sawtooth crashes is estimated as ∼1 ms and comparable to that of the sawtooth-triggered intermediate phases. Not only the zonal flows but also the radial electric fields lag behind the turbulence. Furthermore, the intensities of both the zonal flows and electric fields nearly linearly increase/decrease with the increase/decrease of the turbulence intensity. A double-source predator–prey model analysis suggests that a relatively strong turbulence source may contribute to the dominant zonal flow formation during sawtooth cycles.