Solar wind data from Helios 1 and 2 and from Voyager 1 and 2 are used to show that between 0.3 and 20 AU in the ecliptic plane, the total energy per unit mass contained in the velocity and magnetic field fluctuations decays approximately as a power law of the form R ?α, where R is the heliocentric distance in astronomical units (AU) and ?0.64 ≤ α ≤ ?0.41. It is also shown that to the first order of approximation, this quantity is independent of the effects of solar cycle variations. An analysis of OMNI data at 1 AU from 1969 through 2002 shows that the Alfven ratio, the ratio of kinetic energy to magnetic energy in the fluctuations, exhibits large solar cycle variations rising from 1 or 2 at solar maximum to 8 or 9 either near solar minimum or a couple of years before minimum. This is due to the fact that the kinetic and magnetic energy in the fluctuations both undergo solar cycle variations, with the kinetic energy increasing to a maximum around solar minimum and the magnetic energy decreasing to a minimum around solar minimum. It is found that these effects appear to offset each other so that the sum of the kinetic plus magnetic energies does not exhibit noticeable solar cycle variations.
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