Further measurements of the H+3(v=0,1,2) dissociative recombination rate coefficient

A new flowing afterglow apparatus that utilizes a Langmuir probe/mass spectrometer to monitor both electron and ion decay in a hydrogen plasma has been used to measure the dissociative recombination rate coefficient of H+3 at two different electron temperatures. At 300 K a rate coefficient of 1.5×10−7 cm3 s−1 was found for H+3 ions with a low degree of vibrational excitation (v≤2). The rate coefficient for ground state ions H+3(v=0) was measured as 1.1×10−7 cm3 s−1 at 650 K. A discussion is given of the excitation states of H+3 ions in the afterglow in the light of slow deexcitation rates for low vibrational states. A new model for the recombination of H+3 is presented.