We measure the field transmission matrix t for microwave radiation propagating through random waveguides in the crossover to Anderson localization. From these measurements, we determine the dimensionless conductance g and the individual eigenvalues τn of the transmission matrix tt † whose sum equals g. In diffusive samples, the highest eigenvalue, τ1, is close to unity corresponding to a transmission of nearly 100%, while for localized waves, the average of τ1, is nearly equal to g. We find that the spacing between average values of ln τn is constant and demonstrate that when surface interactions are taken into account it is equal to the inverse of the bare conductance.
In this paper, recent progress on experimental analysis and theoretical models for non-local transport (non-Fickian fluxes in real space) is reviewed. The non-locality in the heat and momentum transport observed in the plasma, the departures from linear flux-gradient proportionality, and externally triggered non-local transport phenomena are described in both L-mode and improved-mode plasmas. Ongoing evaluation of 'fast front' and 'intrinsically non-local' models, and their success in comparisons with experimental data, are discussed
The absolute rate of nonlinear energy transfer among broadband turbulence, low-frequency zonal flows (ZFs) and geodesic acoustic modes (GAMs) was measured for the first time in fusion-grade plasmas using two independent methods across a range of heating powers. The results show that turbulent kinetic energy from intermediate frequencies (20-80 kHz) was transferred into ZFs and GAMs, as well as into fluctuations at higher frequencies (>80 kHz). As the heating power was increased, the energy transfer from turbulence into GAMs and the GAM amplitudes increased, peaked and then decreased, while the energy transfer into the ZFs and the ZFs themselves increased monotonically with heating power. Thus there exists a competition between ZFs and GAMs for the transfer of turbulent energy, and the transfer into ZFs becomes dominant as the heating power is increased. The poloidal-radial Reynolds stress and the mean radial electric field profiles were also measured at different heating powers and found to be consistent with the energy transfer measurement. The results suggest that ZFs play an important role in the low-to-high (L-H) plasma confinement transition.
As the desire to explore opaque materials is ordinarily frustrated by multiple scattering of waves, attention has focused on the transmission matrix of the wave field. This matrix gives the fullest account of transmission and conductance and enables the control of the transmitted flux; however, it cannot address the fundamental issue of the spatial profile of eigenchannels of the transmission matrix inside the sample. Here we obtain a universal expression for the average disposition of energy of transmission eigenchannels within random diffusive systems in terms of auxiliary localization lengths determined by the corresponding transmission eigenvalues. The spatial profile of each eigenchannel is shown to be a solution of a generalized diffusion equation. These results reveal the rich structure of transmission eigenchannels and enable the control of the energy distribution inside random media.
Beta-induced Alfvén eigenmode (BAE) during a strong tearing mode activity (termed as m-BAE) has been observed and investigated in HL-2A. BAE excited by energetic electrons (termed as e-BAE) has been identified both in the Ohmic and ECRH plasma. The hard x-ray spectrum detected by cadmium telluride and the non-thermal radiation measured by electron cyclotron emission are used to analyse the behaviour of the energetic electrons. Experimental results show that the e-BAE is related not only to the populations of the energetic electrons, but also their energy distribution. An interesting result about the BAEs modulated by a supersonic molecular beam and gas puffing is presented. In addition, BAEs during a sawtooth cycle are described in this paper. To assess the identification of the e-BAE and m-BAE, the generalized fishbone-like dispersion relation and magnetic-island-induced BAE dispersion relation are solved near marginal stability, respectively. Compared with experimental results, the calculation analysis shows that the observed frequencies are all close to the theoretical results.
Density profiles in pedestal region (H-mode) are measured in HL-2A and the characteristics of the density pedestal are described. Cold particle deposition by Supersonic Molecular Beam Injection (SMBI) within the pedestal is verified. ELM mitigation by SMBI into the H-mode pedestal is demonstrated and the relevant physics is elucidated. The sensitivity of the effect to SMBI pressure and duration are studied. Following SMBI, the ELM frequency increases and ELM amplitude decreases for a finite duration period. Increases in ELM frequency of SMBI ELM f / 0 ELM f 2-3.5 are achieved. This experiment argues that the ELM mitigation results from an increase in Page 2 higher frequency fluctuations and transport events in the pedestal, which are caused by SMBI. These inhibit the occurrence of large transport events which span the entire pedestal width. The observed change in the density pedestal profiles and edge particle flux spectrum with and without SMBI supports this interpretation. An analysis of the experiment and a model shows that ELMs can be mitigated by SMBI with shallow particle penetration into the pedestal.
Classifiers are lexico-syntactic structures that are common in Chinese but not in English. In 3 studies, the authors demonstrated that classifiers provide a language-inherent classification of objects (affecting perceived similarity and memory) and, more importantly, guide individuals' judgments in a practically relevant context (e.g., in the evaluation of advertisements). Chinese speaking participants, relative to English speaking participants, judged objects sharing a classifier as more similar than objects not sharing a classifier and were more likely to recall them in clusters. Moreover, objects, presented as consumer products in an advertising context, were evaluated more positively when cued with a visual stimulus that triggers classifierrelated associations. Results are discussed in the context of the recent reformulation of the Sapir-Whorf hypothesis.How individuals classify objects into categories constitutes one of the prime issues in cognitive psychology. Research on categorization in the 1970s adopted primarily an observation-
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