THE RELATIVE DISTRIBUTION OF THE MAGNETIC AND PLASMA KINETIC ENERGY DENSITIES IN THE INNER HELIOSPHERE ( < 1 AU)

摘要

The "quasi-invariant parameter" (QI) is defined as the ratio of magnetic energy density to the plasma kinetic energy density. This quantity was found to be a very good proxy for solar activity, correlating strongly with the sunspot number (correlation coefficient > 0.9). A correlation which holds not only for observations at 1 AU, but also at Venus at 0.72 AU. The Helios mission offers the unique possibility of examining QI as a function of radial distance from the Sun in the range 0.3-1 AU for a large part of solar cycle 21. This work will present the systematics of QI variations in the inner heliosphere. The variation of He~(++) with solar cycle and distance from the Sun is taken into account as a factor when calculating QI.