Minor Ion Species in the Solar Wind As Seen with SOHO/Celias/Mtof

Abstract:

The continuous solar wind is typically categorized as either fast or slow wind. Unlike the name implies the constitutive difference between these types of solar wind streams lies not in their respective solar wind velocity but in their elemental compositions. The long-term averages of the dominant ions in the solar wind have been measured with various instruments and are remarkably homogeneous. Here, we are interested in investigating the minor species contained in the solar wind. SOHO/CELIAS/MTOF is a high resolution mass spectrometer which has been continuously operational from 1996 to the present day. The high mass resolution and long life time of MTOF allows to complement the existing observations with the abundances of less abundant species for both typical slow and typical fast solar wind. This allows to further strengthen the characteristics of both types of solar wind. In principle MTOF's time resolution of up to five minutes facilitates to investigate the short-term variability of the solar wind. However, MTOF is a complex instrument that was intended to be in-flight calibrated with its sister instrument SOHO/CELIAS/CTOF. But unfortunately CTOF was only fully operable for about half a year in 1996. Instead we use solar wind data from ACE/SWICS for the calibration of MTOF whenever both instruments are sufficiently close to each other that we can expect them to observe the same solar wind stream.