Ck. Ng et Dv. Reames, FOCUSED INTERPLANETARY TRANSPORT OF SIMILAR-TO-1 MEV SOLAR ENERGETIC PROTONS THROUGH SELF-GENERATED ALFVEN WAVES, The Astrophysical journal, 424(2), 1994, pp. 1032-1048
We present a model of the focused transport of approximately 1 MeV sol
ar energetic protons through interplanetary Alfven waves that the prot
ons themselves amplify or damp. It is based on the quasi-linear theory
but with a phenomenological pitch angle diffusion coefficient in the
''resonance gap.'' For initial Alfven wave distributions that give mea
n free paths greater than approximately 0.5 AU for approximately 1 MeV
protons in the inner heliosphere, the model predicts greater than rou
ghly an order of magnitude amplification (damping) in the outward (inw
ard) propagating resonant Alfven waves at less than or similar to 0.3
AU heliocentric distance. As the strength of proton source is increase
d, the peak differential proton intensity at approximately 1 MeV at 1
AU increases to a maximum of approximately 250 particles (cm2 s sr MeV
)-1 and then decreases slowly. It may be attenuated by a factor of 5 o
r more relative to the case without wave evolution, provided that the
proton source is sufficiently intense that the resulting peak differen
tial intensity of approximately 1 MeV protons at 1 AU exceeds approxim
ately 200 particles (cm2 s sr MeV)-1. Therefore, in large solar proton
events, (1) one may have to take into account self-amplified waves in
studying solar particle propagation, (2) the number of accelerated pr
otons escaping from a flare or interplanetary shock may have been unde
restimated in past studies by a significant factor, and (3) accelerate
d protons escaping from a traveling interplanetary shock at r less tha
n or similar to 0.3 AU should amplify the ambient hydromagnetic waves
significantly to make the shock an efficient accelerator, even if init
ially the mean free path is greater than or similar to 1 AU.