SUMER spectral observations of post-flare supra-arcade inflows

On 21 April 2002 a large eruptive flare on the west limb of the Sun developed a bright, very dynamic, post-flare arcade. In TRACE 195 Angstrom images, a series of dark, sunward moving flows were seen against the bright extreme ultraviolet (EUV) arcade. SUMER obtained a series of spectra of the dark EUV flows in the lines C II, Fe XII, and Fe XXI at a fixed position above the limb. These spectra give spatially resolved line-of-sight velocities and emission measures for the arcade plasma over a temperature range 2 x 10(4) to 10(7) K. The flows are dark in all SUMER lines. The UV continuum longward (similar to1350 Angstrom) and shortward (similar to675 Angstrom) of the hydrogen Lyman limit is used to determine whether the dark 195 Angstrom inflows are due to regions of low plasma density ( plasma voids) or cold absorbing material. There is some evidence of absorption near the front of one of the inflows; however, along most of the dark channels there is no change in continuum ratio and we therefore conclude, as originally suggested by McKenzie and Hudson ( 1999), that they are plasma voids.