Variations of the Cosmic Ray Intensity During Magnetic Storms

A simple mechanism has been suggested by H. Alfvén to explain the main features of the variation of cosmic ray intensity during magnetic storms.

Cosmic ray particles are accelerated or retarded in the electric fields of ionized beams, which are sent out from the sun. Particle orbits hitting the earth have been calculated for different momenta and for solar magnetic fields decreasing with distance as r^–3, r^–2 and r^–1. The influence on the particles of beams of different length and breadth has been analyzed.

A beam length of a few times the orbital radius of the earth and particles with momenta in the range 20–40 GeV Z/c give a time variation in cosmic ray intensity similar to the variation measured during a magnetic storm. This requires a solar magnetic field of 10^–5 gauss at the earth’s orbit.