Electron energy flux in the solar wind

This paper describes studies of electrons between 10 ev and 9.9 kev in the solar wind. The transport of energy in the rest frame of the plasma is evaluated and shown to be parallel to the interplanetary magnetic field. The presence of electrons from solar events causes this energy‐flux density E ∥ to exceed the heat flow H ∥ due to thermal electrons. In one such event, the observations are shown to be consistent with the solar‐electron observations made at higher energies. When observations are made at a point connected to the earth's bow shock by an interplanetary‐field line, a comparatively large energy flux along the field toward the sun is observed, but H ∥ remains outwardly directed during this time interval. In either situation H ∥ is found to be consistent with measurements made on Vela satellites by a different method. These values, less than 1×10 −2 ergs/cm 2 /sec, are sufficiently low to require modifications to the Spitzer‐Harm conductivity formula for use in solar‐wind theories.