Turbulence is a state of fluids and plasma where nonlinear interactions including cascades to finer scales take place to generate chaotic structure and dynamics 1 . However, turbulence could generate global structures 2 , such as dynamo magnetic field, zonal flows 3 , transport barriers, enhanced transport and quenching transport. Therefore, in turbulence, multiscale phenomena coevolve in space and time, and the character of plasma turbulence has been investigated in the laboratory 4-10 as a modern and historical scientific mystery. Here, we report anatomical features of the plasma turbulence in the wavenumber-frequency domain by using nonlinear spectral analysis including the bi-spectrum 11 . First, the formation of the plasma turbulence can be regarded as a result of nonlinear interaction of a small number of irreducible parent modes that satisfy the linear dispersion relation. Second, the highlighted finding here, is the first identification of a streamer (state of bunching of drift waves 12,13 ) that should degrade the quality of plasmas for magnetic confinement fusion 14,15 . The streamer is a poloidally localized, radially elongated global structure that lives longer than the characteristic turbulence correlation time, and our results reveal that the streamer is produced as the result of the nonlinear condensation, or nonlinear phase locking of the major triplet modes.Fluctuation measurements were carried out on the Large Mirror Device-Upgrade linear plasma device 16 (Fig. 1). The axial length of the vacuum vessel is z = 3.74 m and the cylindrical plasma is confined by an axial magnetic field of 0.09 T. (x : horizontal, y : vertical, z : axial, r : radial and θ : poloidal direction.) Positive and negative poloidal directions correspond to the electron and ion diamagnetic drift directions, respectively. The plasma is generated by a helicon wave (the radiofrequency (7 MHz) power is 3 kW, excited by a double-loop antenna around a quartz tube with an axial length of 0.4 m and an inner diameter of 9.5 cm). The quartz tube is filled with argon gas with a pressure of 0.2-0.8 Pa. A linear plasma (radius of 5 cm, electron density/temperature of 10 19 m −3 /3 eV) is generated inside the vacuum vessel 16 . A 64-channel poloidal probe array is installed at the plasma radius r = r p = 4 cm (where the density gradient is steep) and axial position z = 1.885 m. A 48-channel radially movable probe array 17 is installed at the axial position z = 1.625 m. (All 48 channels are used for measurement at r ≥ r p , and 24 channels are used at r < r p , such as r = 2 cm.) A two-dimensionally (2D) movable probe, which is movable in the x-y plane in the plasma cross-section, is installed at the

Zonal flows, which means azimuthally symmetric band-like shear flows, are ubiquitous phenomena in nature and the laboratory. It is now widely recognized that zonal flows are a key constituent in virtually all cases and regimes of drift wave turbulence, indeed, so much so that this classic problem is now frequently referred to as "drift wave-zonal flow turbulence." In this review, new viewpoints and unifying concepts are presented, which facilitate understanding of zonal flow physics, via theory, computation and their confrontation with the results of laboratory experiment. Special emphasis is placed on identifying avenues for further progress.

Multiscale gyrokinetic turbulence simulations with the real ion-to-electron mass ratio and β value are realized for the first time, where the β value is given by the ratio of plasma pressure to magnetic pressure and characterizes electromagnetic effects on microinstabilities. Numerical analysis at both the electron scale and the ion scale is used to reveal the mechanism of their cross-scale interactions. Even with the real-mass scale separation, ion-scale turbulence eliminates electron-scale streamers and dominates heat transport, not only of ions but also of electrons. Suppression of electron-scale turbulence by ion-scale eddies, rather than by long-wavelength zonal flows, is also demonstrated by means of direct measurement of nonlinear mode-to-mode coupling. When the ion-scale modes are stabilized by finite-β effects, the contribution of the electron-scale dynamics to the turbulent transport becomes non-negligible and turns out to enhance ion-scale turbulent transport. Damping of the ion-scale zonal flows by electron-scale turbulence is responsible for the enhancement of ion-scale transport.

The configuration of multiple hydrogen atoms trapped in a tungsten monovacancy is investigated using first-principles calculations. Unlike previous computational studies, which have reported that hydrogen in bcc metal monovacancies occupies octahedral interstitial sites, it is found that the stable sites shift toward tetrahedral interstitial sites as the number of hydrogen atoms increases. As a result, a maximum of twelve hydrogen atoms can become trapped in a tungsten monovacancy.

of the anomalous transport, which is caused by microscopic fluctuations, on the pressure-gradient-driven modes is analysed. The E X B nonlinearity is renormalized as a form of the transport coefficient such as the thermal diffusivity, the ion viscosity and the current diffusivity. Destabilization by current dsusivity and stabilization by thermal transport and ion viscosity are analysed. By use of the mean-field approximations, the nonlinear dispersion relation is solved. Growth rate and stability conditions are expressed in terms of the renormalized transport coefficients. The transport coefficients in the steady state are obtained by the marginal stability condition for the microscopic ballooning mode in tokamaks. A formula for the anomalous transport is obtained. The role of the pressure gradient in enhancing the anomalous transport is identified. An important role is found for the collisionless skin depth. Effects of geometrical parameters such as the rotational transform ,and magnetic shear are also quantified. Comparison with experimental observations shows a good agreement in a various aspects of the L-mode confinement, including the dependences on the ion mass, plasma current, internal inductance and reversed shear. The large transport coefficient at the edge is also explained. The typical wavenumber and level of fluctuations for self-sustained turbulence are also obtained.