![]() ![]() ![]() However, it is concluded that in the limit of flat-density profiles characteristic of H-mode discharges, the stabilizing influence of more » perpendicular compressibility is insufficient to corroborate an improvement, if any, in ion confinement quality. Results indicate that the slab and toroidal branches of these instabilities are of comparable importance, and are both strong candidates to explain the observed anomalous ion loss in toroidal fusion devices. An analytic dispersion relation that retains ion drift resonances, and keeps the leading-order contribution from finite Larmor radius effects and parallel compressibility, is derived. « lessĪ unified theory of ion-pressure-gradient-driven drift wave instabilities and transport is presented, which ties the long-wavelength trapped-ion mode to the moderate-wavelength hydrodynamic mode in toroidal geometry. Here this work casts new insights into the nature of ECDI and the associated anomalous transport and demonstrates the potential of the two-fluid moment model in efficient modeling of E × B plasmas. The force balance properties are also studied using the five-moment simulation data. The development of the instability, as well as the anomalous transport, is confirmed and in excellent agreement with theoretical predictions. We then carry out direct numerical simulations of the cross-field setup using the five-moment model. The dependence of the instability on ion-to-electron mass ratio, plasma temperature, and background B field strength is also thoroughly explored. Also, by including more (> = 10) moments, secondary (and possibly higher) unstable branches can be recovered. At low temperatures, the two-fluid models predict the fastest-growing mode in good agreement with the kinetic result. We will first present linear analyses of the instability in the two-fluid five- and ten-moment models, and compare them against the fully-kinetic theory. By treating both electron and ion species on an equal footing, the free energy due to the inter-species velocity shear allows the growth of an anomalous electron flow parallel to the background E field. In this work, however, we demonstrate that a reduced variant of this instability, and more importantly, the associated anomalous transport, can be treated self-consistently in a collisionless two-fluid framework without any adjustable collision parameter. ![]() The development of ECDI and anomalous transport is often considered requiring a fully kinetic treatment. Such anomalous transport more » is important due to its role in particle thermalization at space shocks, and in causing plasma flows towards the walls of E × B devices, leading to unfavorable erosion and performance degradation, etc. A prominent feature of ECDI is its capability to induce an electron flow parallel to the background >E field at a speed greatly exceeding predictions by classical collision theory. This occurs in, for example, collisionless shock ramps in space, and in E × B discharge devices such as Hall thrusters. In the presence of a strong electric field perpendicular to the magnetic field, the electron cross-field (E × B) flow relative to the unmagnetized ions can cause the so-called electron cyclotron drift instability (ECDI) due to resonances of the ion acoustic mode and the electron cyclotron harmonics. It is shown that the MTSI mode results in strong parallel heating of = , Furthermore, the latter mode having a finite wavelength along the magnetic field is identified as the Modified Two-Stream Instability (MTSI). An intense but slowly growing mode with a distinct eigen-mode structure along the magnetic field develops at a later nonlinear stage enhancing the tendency toward long wavelength condensation. Tendency to generate long wavelength components is most clearly observed in the spectra of the electron density and the anomalous current fluctuations. At the same time, nonlinear evolution of fluctuations of the ion and electron density, as well as the anomalous electron current, shows cascade toward long wavelengths. It is found that the instability develops as a sequence of growing cyclotron harmonics demonstrating wave breaking and complex nonlinear interactions, being particularly pronounced in ion density fluctuations at short wavelengths. The emphasis is on two-dimensional effects involving the parallel dynamics along the magnetic field in a finite length plasma with dielectric walls. The Electron Cyclotron Drift Instability driven by the electron E × B drift in partially magnetized plasmas is investigated with highly resolved particle-in-cell simulations. ![]()
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