CORONAL PROTON TRANSPORT IN THE PRESENCE OF ALFVEN WAVES AND IMPLICATIONS FOR IMPACT LINE LINEAR-POLARIZATION

The transport of fast (∼ 1 MeV) protons in the corona is considered when their density and anisotropy are sufficiently large to excite Alfvén waves. The Alfvén waves scatter the protons and make them almost iso tropic. The Alfvén wave instability remains in a marginally stable state in which the proton anisotropy is just large enough to excite Alfvén waves to a level which would eliminate any greater anisotropy. The protons propagate diffusively down a coronal loop and have a path length of order 100 times their length in the absence of Alfvén waves. This increases their Coulomb losses, and much higher energy protons (2-20 MeV) are required initially to produce Ha impact line linear polarization in the chromosphere as compared to the case in the absence of Alfvén waves (∼ 200 keV) for loop lengths ∼ 109 cm. The interpretation of the observed polarization becomes less direct because it depends on more poorly known parameters than in the case of the absence of Alfvén waves.