The possibility is studied of the fast decay of an atomic hydrogen pla
sma jet due to desorption of excited hydrogen molecules from the chamb
er walls and their subsequent transport into the jet by gas-dynamic vo
rtices. The problem is considered using a simple model including time-
dependent two-dimensional gas dynamics of a buffer gas, diffusion, and
ion-molecule reactions of hydrogen both in a volume and on the walls
of a chamber. The conditions and geometry of the problem correspond to
a chemical reactor for depositing thin films by means of plasma jets.
Numerical calculations show that, when the content of desorbed excite
d molecules is sufficiently large, the plasma of the jet relaxes rapid
ly due to charge-exchange and dissipative-recombination reactions.