In a normal and an abnormal ELCAD plasmas the density of electrons and
positive ions were estimated from the earlier measured values of the
cathodic current density, the cathode fall, the electric field, the length
of cathode dark space, the kinetic energy, the last free path of positive
ions hitting the cathode and the rate of secondary electron emission. In a
normal ELCAD, the density of positive ions forming the space charge:
$n_{sp}^{+}$
≈ 5.7×1012 cm-3, the density of positive ions hitting the
cathode: n+ ≈ 1.1×1012 cm-3, the electron density at the cathode:
$n_{e,c}$
≈ 3.7×1011 cm-3, the electron density at the end of cathode dark
space: ne ≈ 5.7×1012 cm-3 and the multiplication of electron in cathode
dark space M ≈ 15.3 were obtained. In an abnormal case, $n_{sp}^{+}$
≈ 2.1×1013 cm-3,
n+ ≈ 4.3×1012 cm-3, $ n_{e,c}$
≈ 3.9×1012 cm-3, ne ≈ 2×1013 cm-3, M ≈ 5.17 were
received.