Energy in density gradient

Abstract

Inhomogeneous plasmas and fluids contain energy stored in inhomogeneity and they naturally tend to relax into lower energy states by developing instabilities or by diffusion. But the actual amount of energy in such inhomogeneities has remained unknown. In the present work the amount of energy stored in a density gradient is calculated for several specific density profiles in a cylindric configuration. This is of practical importance for drift wave instability in various plasmas, and in particular in its application in models dealing with the heating of solar corona because the instability is accompanied with stochastic heating, so the energy contained in inhomogeneity is effectively transformed into heat. It is shown that even for a rather moderate increase of the density at the axis in magnetic structures in the corona by a factor 1.5 or 3, the amount of excess energy per unit volume stored in such a density gradient becomes several orders of magnitude greater than the amount of total energy losses per unit volume (per second) in quiet regions in the corona. Consequently, within the life-time of a magnetic structure such energy losses can easily be compensated by the stochastic drift wave heating.

arXiv comment6 pages, 6 figures

References in corpus (6)

• The universally growing mode in the solar atmosphere: coronal heating by drift waves
• Drift waves in the corona: heating and acceleration of ions at frequencies far below the gyro frequency
• A new paradigm for solar coronal heating
• Kinetic instability of drift-Alfven waves in solar corona and stochastic heating
• Electric fields in solar magnetic structures due to gradient driven instabilities: heating and acceleration of particles
• Solar nanoflares and other smaller energy release events as growing drift waves