Spectroscopic determination of turbulent Langmuir fields in a REB-heated plasma

Spectroscopic measurements of the Stark component of plasma emission lines have proved to be an efficient tool at determining the strength of turbulent Langmuir fields excited in a plasma by an intense relativistic electron beam (REB). Recently, at the REBEX experimental facility, H_α and H_β line profiles with excellent spectral, temporal and spatial resolution have been obtained by means of an advanced imaging spectrograph combined with a gated image intensifier. In this paper we report model calculations of the H_α line profiles, which make it possible to distinguish the Stark component of the investigated lines from the strong Doppler background observed in the experiment, and, thus, to estimate the level of the Langmuir turbulence in the REBEX plasma