Lennard A. Fisk
University of Michigan
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Primary Section: 16, Geophysics Membership Type:
Member
(elected 2003)
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Research Interests
I am a theoretician who studies a broad-range of plasma and energetic particle phenomena in the atmosphere of the Sun and the heliosphere, the region of space carved out by the expansion of the solar atmosphere, the solar wind. In this field there have been a number of exciting observations for which new theories needed to be developed. In 1974, I proposed that the newly discovered anomalous cosmic rays, highly overabundant in helium, oxygen, nitrogen and neon, are interstellar atoms that are ionized in the solar wind, and then accelerated by four orders of magnitude in the outer heliosphere. This theory, confirmed by subsequent observations, has influenced our current understanding that the heliosphere is a dynamic and interesting astrophysical location. In 1978, I introduced a plasma-heating model that accounted for the newly observed Helium-3 rich solar flares, in which this isotope is greatly enhanced. In 1996, I developed a new model for the configuration of the magnetic field in the heliopshere to explain the unexpected transport of energetic particles in solar latitude. This model, in which the solar magnetic field undergoes systematic motions, has led to my recent research on the evolution of the solar magnetic field during the solar cycle, the acceleration of the solar wind, and the acceleration of energetic particles in the solar wind.
