CORONAL ELECTRON STREAM AND LANGMUIR WAVE DETECTION INSIDE A PROPAGATION CHANNEL AT 4.3 AU

Observations of an energetic interplanetary electron event associated with the production of Langmuir waves, both of which are identified at 4.3 AU by instruments on the Ulysses spacecraft, are presented in thi s paper. This electron event propagates inside a well-defined magnetic structure. The existence of this structure is firmly established by j oint particle and plasma observations made by Ulysses instruments. Its local estimated radial width is of the order of 2.3 x 10(7) km (0.15 AU). The electron beam is associated with a type III burst observed fr om Earth at high frequencies and at low frequencies from Ulysses in as sociation with Langmuir waves detected inside the structure. The consi stency of local (Ulysses) and remote (Earth) observations in terms of temporal and geometrical considerations establishes that the structure is anchored in the solar corona near the solar active region responsi ble for the observed type III emission and gives an accurate determina tion of the injection time for the observed electron beam. The width o n the solar surface of the structure is estimated to be 6000 km. Propa gation analysis of the electron event is presented. It is shown that t his event is nearly scatter-free. Ion plasma velocity variations insid e the structure were very small in amplitude as well as in direction. The magnetic field inside this structure was also very quiet and organ ized. In order to quantify the magnetic field properties, a variance a nalysis has been performed and is presented in this paper. The analysi s establishes that inside the structure the amount of magnetic energy involved in the fluctuations is less than 4% of the total magnetic ene rgy; the minimal variance direction is well defined and in coincidence with the direction of the mean magnetic field. This configuration may produce conditions favorable for scatter free streaming of energetic electrons and/or Langmuir wave production. The results presented show that the magnetic field might play a role in stabilizing the coronal-o rigin plasma structures and then preserving them to large, similar to 4 AU, distances in the heliosphere.