EUV spectroscopic observations of spray ejecta from an X2 flare

An X2.3 class flare was reported on 10 April 2001 in AR 9415. A halo coronal mass ejection (CME) was associated with this flare. The Coronal Diagnostic Spectrometer (CDS) on board the Solar and Heliospheric Observatory (SOHO), which was running in its daily synoptic mode, recorded a very high-velocity ejection of plasma associated with this activity. The spatial scanning and spectral capabilities of CDS allow the measurement of both transverse and line-of-sight velocities. Components of the plasma, as seen in emission from O v at around 2.5x10(5) K, reached transverse velocities in excess of 800 km s(-)1. The nature of the spectral line profiles suggests that a rotational motion of +/- 350 km s(-1) was superimposed upon the general outward expansion of approximately 150 km s(-1). The ejection detected using CDS was found to have a constant acceleration and is thought to be a spray of plasma with a helical structure driven by the magnetic topology.