  In this report, we describe characteristics of a ring-structure hydrogen
plasma heated in electron cyclotron resonance conditions and confined in a
mirror magnetic trap and discuss the relative efficiency of secondary electrons
and thermoelectrons in negative hydrogen and deuterium ion production. The
obtained data and calculations of the balance equations for possible reactions
demonstrate that the negative ion production is realized in two stages. First,
the hydrogen and deuterium molecules are excited in collisions with the plasma
electrons to high-laying Rydberg or vibrational levels in the plasma volume.
The second stage leads to the negative ion production through the process of
dissociative attachment of low energy electrons. The low energy electrons are
originated due to a bombardment of the plasma electrode by ions of one of the
driven rings and thermoemission from heated tungsten filaments. Experiments
seem to indicate that the negative ion generation occurs predominantly in the
limited volume filled with thermoelectrons. Estimation of the negative ion
generation rate shows that the main channel of and ion production involves the
process of high Rydberg state excitation.
