The application of a rotating electric quadrupole field to a pure electron plasma confined in an elongated Penning trap of the Malmberg type operating at 1 Tesla is shown to produce an unusually long‐lived state. The observations are consistent with an assumption that the rotating field suppresses the radial expansion from transport due to alignment imperfections that normally limits the lifetime of such a plasma to a few thousand seconds. With the rotating field in operation, a lifetime of 20 hours was obtained. © 1995American Institute of Physics