Abstract—Both observational evidence and theoretical study
suggests the presence of a plasma double layer (DL) above the
surface of the Sun. Such a DL, together with a single charge layer
(SL) directly below it, provides a possible explanation for the
existence of the temperature minimum in the lower corona, the xray
emissions observed above sunspots, and the enigmatic
variations observed in the intensity of the solar wind current. This
plasma sheath is arguably a generic feature, in varying degree,
around all stars.
Index Terms— Plasma sheaths, plasma properties, solar
atmosphere, solar corona, solar wind velocity, temperature
inversions, photosphere, velocity distribution.
I. INTRODUCTION
One of the most persistently enigmatic observations of the
near-solar environment is the temperature inversion that
includes the rise in temperature from approximately 5000K on
the photosphere to over 2 million K in the lower corona.
Immediately above the photosphere, the chromosphere
supports a temperature rise from ~5,000K to 20,000K with
increasing altitude above the solar surface. Above that, the
transition region is a thin, irregular layer in the Sun’s
atmosphere that separates the chromosphere from the hot
lower corona. In this transition region temperatures rise from
~20,000K to over 2 million K. This abrupt rise in temperature
with increasing altitude above the surface has been one of the
most unrelenting enigmas in our knowledge of the workings of
the Sun [1]. Because the solar atmosphere is constituted of
plasma, it has recently been suggested that a well-known
plasma phenomenon, the double layer (DL) may be involved in
a causal way in this mechanism. [.....]
