Analytical solution for minimum length MHD ACCELERATOR with constantpressure.
along the other two trajectories of Fig. 1. We can conclude then that there is discrimination only when the spacecraft is near the apex of the shadow or near its edge. Though this result could have been anticipated, it is felt to be of value to exhibit it quantitatively. In this exploratory study we have ignored complications introduced by centers of activity and ray structure. The sun lacks heliocentric symmetry and this will make interpretation more difficult. A helpful feature is that the emission from a complex distribution may be expressed as the sum of emissions from its parts; with a knowledge of the locations on the sun of bright regions, a set of integrals [Eq. (1) ] could be summed to improve the theoretical model. The important question of how much EUV radiation is scattered by the Earth's atmosphere to the observation point from the occulted part of the chromosphere will be examined in later work. However, a rough overestimate, considering scattering to occur in a uniform belt of upper atmosphere 100 miles thick in which the scattering efficiency is 100%, shows that this scattered radiation can compete with direct coronal light only if all but 10 ~ of the chromospheric emission is eclipsed. This strongly indicates that the Earth is a good occulting disk in the EUV.