in recognition for his outstanding work in space physics

 Dr Carl E. McIlwain was the first to recognize, on the basis of sounding rocket measurements, the existence of magnetic-field aligned acceleration of primary auroral electrons.

He made the organization of data on radiation belt particles possible by introducing the magnetic shell parameter, L, whose definition is based on the existence of three adiabatic invariants of the motion of such magnetically trapped particles. The L coordinate system has become universally used as the principal tool for organizing magnetospheric phenomena. 

His measurements of protons and electrons at the geostationary orbit with the ATS-5 spacecraft provided deep insights into the injection of plasma into the inner magnetosphere and its redistribution therein. Based on that, Dr McIlwain deduced global models of the magnetospheric convection field which found wide applications.

Beyond these major achievements, he has been an active researcher on a broad spectrum of subjects. He also was one of the key actors in developing the electron beam technique for measuring electric fields towards high time resolution and under strongly varying conditions. 

Newsletter 67, 38, 1998