81 research outputs found
The universally growing mode in the solar atmosphere: coronal heating by drift waves
The heating of the plasma in the solar atmosphere is discussed within both
frameworks of fluid and kinetic drift wave theory. We show that the basic
ingredient necessary for the heating is the presence of density gradients in
the direction perpendicular to the magnetic field vector. Such density
gradients are a source of free energy for the excitation of drift waves. We use
only well established basic theory, verified experimentally in laboratory
plasmas. Two mechanisms of the energy exchange and heating are shown to take
place simultaneously: one due to the Landau effect in the direction parallel to
the magnetic field, and another one, stochastic heating, in the perpendicular
direction. The stochastic heating i) is due to the electrostatic nature of the
waves, ii) is more effective on ions than on electrons, iii) acts predominantly
in the perpendicular direction, iv) heats heavy ions more efficiently than
lighter ions, and v) may easily provide a drift wave heating rate that is
orders of magnitude above the value that is presently believed to be sufficient
for the coronal heating, i.e., J/(ms) for active
regions and J/(ms) for coronal holes. This heating
acts naturally through well known effects that are, however, beyond the current
standard models and theories.Comment: To appear in MNRA
Solar Wind Turbulence and the Role of Ion Instabilities
International audienc
Deep Groundwater Flow Patterns Induced by Mine Water Injection Activity
Mine water injection into deep formations is one of the effective approaches for reducing the drainage from coal mines in the arid and semi-arid region of the Ordos basin, China. Many coal mines are attempting to execute the related projects. Under the influence of groundwater protection, the understanding of regional groundwater flow is becoming highly important to the mine water monitoring, whereas quite few academic research teams focus on the deep groundwater flow pattern by mine water injection. This paper reveals the spatial distribution of Liujiagou Formation that is in positive correlation with the terrain, and its local thickness is influenced by the dominant W-E and NE-SW directions of geological structures. Only a part of sandstone rocks consists of aquifers, the rest 61.9% of relatively dry rock provide the enhanced storage space and partial mudstone aquicludes decrease the possibility of the vertical leakage for mine water. The dynamic storage capacity is evaluated at 2.36 Mm3 per 1 km2 and over 25.10 billion m3 in this study area. Two hydrogeologic cross-sections of basin-scale identify the W-E and N-S regional groundwater flow directions, with the lower Yellow River catchment becoming the discharged region. The hierarchically and steadily nested flow systems containing coal mining claims are influenced by coal mining activity. The groundwater depression cone in a shallow coal measure aquifer is caused by mine water drainage whereas the groundwater mound in Liujiagou Formation is generated by mine water injection activity. The numerical simulation revealed that the groundwater head rebound is slightly decreased and will not recover to its initial baseline within 500 years due to its low porosity and permeability. This study elucidates the deep groundwater flow patterns induced by mine water injection and provides a practical methodology for the management and pollution monitoring of mine water injection activity
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