Among the scientific objectives of UVCS is the observation of ``bullets" or ``jets" above the quiet chromosphere. Such observations have been made previously at several occasions with the HRTS--instruments at given wavelengths, e.g. of C IV or O VI etc. It is proposed to put some emphasis on weakly ionized (or neutral) species of as many elements as possible within the range of wavelengths of UVCS.
These observations are extremely interesting as they pertain to the question of the origin of the solar wind and the feeding of solar wind with minor ions. The ``official" picture (e.g. Bürgi 1992, or Bürgi and Geiss 1986) which describes the solar wind as a steady--state phenomenon has been successful in reproducing many of the observed features like charge--state distribution, helium depletion etc. The alternative picture would be to have, at least in the innermost corona, a non--stationary solar wind with a principally patchy nature, made up from plasmoids emanating and being pushed upwards through the ambient (magnetic) pressure of the background corona. The evidence for such a scenario comes largely from the observation of explosive events near the solar limb. Some additional evidence comes from the observations of the Lindau--Group, indicating, that the quiet solar wind at 0.3 AU is highly structured as well, with a strong periodicity of magnetic pressure and gas pressure, caused by the existence of flux--ropes. It is still not clear, how the two representations of the solar wind, the steady--state picture and the grainy--picture, have to be merged; or, if the low energy solar particle flow in the inner corona is organised in plasmoids or bubbles, what the further fate of plasmoids or jets might be. We have made some preliminary investigations and found that weakly ionized species at high altitudes above the solar limb might serve as powerful diagnostics for a ``grainy" solar wind in the inner corona.
It is therefore proposed to conduct a systematic search for lines of weakly
ionized species above the solar surface. This search should be done above
active regions but also above quiet areas and above coronal holes.
It may be possible, though difficult, to follow
plasmoids from the solar limb to
the outer range of the field of view, moving the aperture within one or two
hours radially across the corona. A probably more realistic and appealing
option is to look for some time at a given line at one
place and try to take a ``statistical" average of grainy features as
function of the distance above the solar limb.
Possible interesting candidates for observations are C III, N II, N III,
etc. in the Ly--
channel, and Si III, S II and S III in
the O VI channel of the instrument.
As a corollary to these observations, one could also make a search for cometary debris using this technique. The point of this observation is that, even if negative, it will provide extremly valuable information for the question of the feeding of the solar wind.
Correlated observations : with CELIAS (possibily with LASCO, SUMMER, and CDS) (Observational Specifications as for CME program, with low ionization lines).