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[en] The experimental X-ray mass absorption coefficients data of the most usual absorbants (aluminium, beryllium and nickel) were subject to a careful computational processing. The best fits for these values are given. This note presents some useful computations to facilitate the filter method use for the hot plasma electron temperature determination. (author)
[en] The drift waves related to the magnetic plasma confinement are observed in confinement devices. A number of mechanisms are theoretically shown to be able to render them instable. ODE experiments devoted to the study of their behavior in connection with a specific stabilizing mechanism (collisionnal wave, resonant wave and partly trapped electron wave) shown a strong agreement between observations and theoretical predictions in the laminar range
[fr]Les ondes de derive liees au confinement magnetique des plasmas sont observees dans des appareils de confinement. La theorie montre que de nombreux mecanismes peuvent les rendre instables. Les experiences ODE consacrees a l'etude de leur comportement en liaison avec un mecanisme destabilisant specifique (onde collisionnelle, onde resonnante et en partie onde d'electrons pieges) ont montre un accord tres pousse entre les observations et les previsions de la theorie dans le domaine laminaire
[en] We present observations of hot plasma from solar eruptions recorded by the Atmospheric Imaging Assembly (AIA) on the Solar Dynamics Observatory. AIA is the first narrowband instrument capable of taking images of hot plasma in the 5-15 MK range. We find that there are hot structures above flare loops, and that they are typically more diffuse and nebulous than the well-defined flare loops. Because of the narrowband response, high sensitivity, and high spatial resolution of AIA, these supra-arcade structures are visible in exquisite detail, particularly in the 131 A and 94 A channels. In one event, a C4.9 flare observed on 2010 November 3, hot plasma is seen to outline an erupting plasmoid and possibly a current sheet. We compare hot plasma observed with AIA to structures observed with the X-Ray Telescope on the Hinode mission and find that the plasma imaged in AIA contains more fine detail. These new AIA observations show that supra-arcade flare structures and coronal mass ejections are highly structured not only in space and time, but also in temperature. This thermal structuring is expected, based on modeling efforts, but has now been imaged directly for the first time over a large range of temperatures.
[en] The stability of the boundary regions of gas insulated plasmas are important for two reasons. Firt, large pressure and density gradients are likely to arise across the boundaries on account of plasma neutral gas interaction effects. Second, minimum-average-B and shear are expected to become less effective due to insufficient magnetic line tying and the small localization regions of the modes considered respectively. In this communication we discuss the joint effects of plasma neutral gas interaction and resistivity on the stability of electrostatic current convective modes. Within specific parameter ranges strong stabilizing effects are introduced
[en] This paper presents the first direct experimental measurements of the Salpeter enhancement of collisions due to particle correlations. The perpendicular-to-parallel collision rate νperpendicular|| is measured in laser-cooled pure ion plasmas, spanning the regimes from weak to strong magnetization, and from weak to strong particle correlations. The abrupt suppression of collisions in the strongly magnetized regime of T < or approx. 10-3 eV is observed, mitigated by the Salpeter enhancement when correlation effects become significant. This νperpendicular|| enhancement due to correlations is directly analogous to the enhancement of fusion collisions in hot dense stellar plasmas. The measured collisional enhancement is approximately exp(Γ), where Γ is the correlation parameter, and this is quantitatively consistent with analytical estimates based on thermal equilibrium shielding and correlations.
[en] In this brief report, I summarize the rather involved recent work of Brown, Preston, and Singleton (BPS). In Refs.  and , BPS calculate the energy partition into ions and electrons as a charged particle traverses a non-equilibrium two-temperature plasma. These results are exact to leading and next-to-leading order in the plasma coupling g, and are therefore extremely accurate in a weakly coupled plasma. The new BPS calculations are compared with the more standard work of Fraley et al. . The results differ substantially at higher temperature when TI ≠ Te.
[en] Measurements of electron cyclotron radiation near the fundamental frequency on the high and low magnetic field side of the TFR Tokamak are reported. In the presence of a superthermal electron component the measured intensities are asymmetric. A theoretical explanation based on the combined effects of the electron relativistic mass variation and the 1/R variation of the tokamak magnetic field is discussed