  Novel methods for diagnostics of molecular hydrogen plasma processes, such as
ionization, production of high vibrational levels, dissociation of molecules
via excitation to singlet and triplet states and production of metastable
states, are presented for molecular hydrogen plasmas in corona equilibrium. The
methods are based on comparison of rate coefficients of plasma processes and
optical emission spectroscopy of lowest singlet and triplet transitions, i.e.
Lyman-band ($B^1\Sigma^+_u \rightarrow X^1\Sigma^+_g$) and molecular continuum
($a^3\Sigma^+_g \rightarrow b^3\Sigma^+_u$), of the hydrogen molecule in VUV
wavelength range. Comparison of rate coefficients of spin-allowed and/or
spin-forbidden excitations reduces the uncertainty caused by the
non-equilibrium distributions of electron energy and molecular vibrational
level, which are typically known poorly in plasma sources. The described
methods are applied to estimate the rates of various plasma processes in a
filament arc discharge.
