Based on He I 10 830 Angstrom triplet observations, we determined the physi
cal parameters of the solar chromosphere: thermal and turbulent velocities,
excitation temperature, effective kinetic temperature, and number of He at
oms at the 2(3)S level. An analysis of spatial variations in these paramete
rs provides new information about thin magnetic flux tubes filling the chro
mosphere. The observed dependence of filling factor on the depth of the mai
n component in the He I 10 830 Angstrom triplet, on heliocentric angle, and
on effective temperature lends support to the following model. A partially
ionized plasma rises from the photosphere along each magnetic flux tube to
the upper chromosphere. Here, the outflow of neutral atoms across magnetic
field Lines leads to an ion-neutral separation. The neutrals fill a more e
xtended region-a "cloud" near the upper part of the flux tube. In active re
gions, we observe the overlapping of He I clouds in the upper chromosphere.