  The background motivation, and some preliminary results, are reported for a
recently begun investigation of a potentially important mechanism for
electromagnetic radiation from space, Double Layer Radiation (DL-radiation).
This type of radiation is proposed to come from DL-associated, spatially
localized high frequency (hf) spikes that are driven by the electron beam on
the high-potential side of the double layer. It is known, but only
qualitatively, from laboratory experiments that double layers radiate in the
electromagnetic spectrum. In our experiment the spectrum has high amplitude
close to the plasma frequency, several hundred MHz. No clear theoretical model
exists today. The quantitative evaluation is complicated because measurements
are made in the near field of the radiating structure, and in the vicinity of
conducting laboratory hardware that distorts the field. Because the localized
electrostatic wavelengths (approximately 1 cm) can be relatively small compared
to the emitted electromagnetic wavelengths, the situation is further
complicated. We discuss the mutual influence between the ion density profile
and hf-spike formation, and propose that some kind of self-organization of the
density profile through the ponderomotive force of the hf spike might be
operating. First results regarding the electromagnetic radiation are reported:
the frequency, the time variation of the amplitude, and the spatial
distribution in the discharge vessel.
