VOYAGER OBSERVATIONS OF THE MAGNETIC-FIELD IN THE DISTANT HELIOSPHERE

The latitudinal structure of the heliospheric magnetic field during mu ch of the solar cycle is determined by a ''sector zone'', in which bot h positive and negative magnetic polarities are observed, and by the u nipolar regions above and below the sector zone. Distinct corotating s treams and interactions regions are found primarily in the sector zone during the declining phase of the solar cycle. Within a few AU, the s treams and interaction regions are distinct and are related to solar f eatures. A restructuring of the solar wind occurs between 1 AU and app roximate to 15 AU, in which the isolated streams, interaction regions and shocks merge to form compound streams and merged interaction regio ns (''MIRs''). Memory of the source conditions is lost in this process . In the region between approximate to 30 AU and the termination shock (the ''distant heliosphere''), the pressure of interstellar pickup pr otons dominates that of the magnetic field and solar wind particles an d largely controls the dynamical processes. During 1983 and 1994, coro tating streams and corotating interaction regions were observed at 1 A U. Merged interaction regions were observed at approximate to 15 AU in 1983, but not at approximate to 45 AU during 1994. This result sugges ts a further restructuring of the solar wind in the distant heliospher e, but variations from one solar cycle to the next might also contribu te to the result. Approaching solar minimum in 1996, the latitudinal e xtent of the sector zone decreased, and Voyager 2 gradually entered th e unipolar region below it. The speed was lower in the sector zone tha n below it. At Voyagers 1 and 2, the change in cosmic ray intensity is related to the magnetic field strength during each year from 1983 thr ough 1996. The magnetic field strength has a multifractal distribution throughout the heliosphere. This fundamental symmetry of the heliosph ere has not been incorporated explicitly in cosmic ray propagation mod els.