Abstract
Helium abundance variations in the solar wind have been studied using data obtained with Los Alamos plasma instrumentation on IMP 6, 7, and 8 from 1971 through 1978. For the first time, average flow characteristics have been determined as a function of helium abundance, A(He). Low and average values of A(He) are each preferentially identified with a different characteristic plasma ‘state’ these correspond to what have previously been recognized as the signatures of interplanetary magnetic field polarity reversals and high speed streams, respectively. Helium enhancements at 1 AU also can be identified with a characteristic plasma state, which includes high magnetic field intensity and low proton temperature. This is further evidence that such enhancements are a signal of coronal transient mass ejections. Long-term averages of A(He) at least partially reflect the relative frequency with which coronal streamers, holes, and transients extend their influence into the ecliptic plane at 1 AU. As a result, there is a real and pronounced solar cycle variation of solar wind H(He).
Published Version
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