Interplanetary Magnetic Field and Its Control of Cosmic-Ray Variations

A model interplanetary magnetic field is described which may explain some features of solar cosmic-ray increases and also fluctuations in the primary radiation. The main features are as follows: (1) A chromospheric "explosion" occurs at the time of a flare in gas permeated by the sunspot field. The gas, linked with magnetic flux {}10²¹ gauss cm², is ejected from the vicinity of the sun.(2) The gas and field remain linked and the latter is so distorted that solar cosmic-rays are released {~}{}-1 hour after the flare.(3) The trailing radial field is drawn out past the earth's orbit to form a magnetic cone with closed ends. The life of the interplanetary field is at least a few months and a number of segments may be built up from different spot fields. The general field may contribute, being extended to largely radial form by a general outward movement of gas.(4) Cosmic rays released after one flare may be influenced by the radial field resulting from a previous flare associated with the same, or perhaps a different, spot group.(5) On February 23, 1956, the magnetic cone enclosing the earth contained irregularities separated by {~}0.5 astronomical unit, capable of deflecting 15-Bev protons up to {~}20^∘{} and completely scattering 1.5-Bev protons. Cosmic-ray diffusion was anisotropic, the rate being {~}65 times greater along the field than across the field. The main features of the solar increase may be explained by such a field.(6) Some observed variations of primary cosmic radiation (Forbush-type decreases, 27-day and diurnal variations) may be qualitatively explained by the model.(7) The model may explain auroras in terms of ions of intermediate energy ({~}10⁵ev) transported from the sun in the magnetic cone which reaches the earth in a day or two and may inclose it for many days or weeks.