Lecturer: M. Yamauchi (IRF) Date: 2007-03-29 10:00 Place: Aula
Ion Pickup Phenomenon upstream of the Mars observed by ASPERA 3
Swedish Institute of Space Physics
The Mars Express (MEX) Ion Mass Analyser (IMA) often observed cycloid distributions (two dimensional partial ring distributions in velocity phase space) of protons flowing anti-sunward upstream of the Martian bow shock. Since ions are expected to gyrate around the interplanetary magnetic field (IMF) in velocity phase space, the observation suggests that a source of plasma with nearly the same initial velocity (low temperature) exists over a wide range upstream of the Mars. Using several analyses techniques, the initial velocity is fount to be nearly zero, and the only reasonable explanation for the source plasma is the newly ionized hydrogen corona. Since the ring plane is perpendicular to the IMF, the ring data is also useful in estimating the IMF orientation at MEX which does not have the magnetometer. However, this derivation is not very easy when using the actual IMA data which is not designated for such derivation. I present the current status of the derivation method. If I have time, I would also mention the other component that the pick up ions of hydrogen corona origin.
Created 2007-03-29 12:08:36 by Mats HolmstrÃ¶m Last changed 2007-03-29 12:08:36 by Mats HolmstrÃ¶m