Recombination of neutral hydrogen atoms on AISI 304 stainless steel surface

The recombination coefficient of neutral hydrogen atoms in the ground state on polycrystalline AISI 304 stainless steel surface was determined experimentally. The H source was an inductively coupled RF hydrogen plasma with the density of 10(16) m(-3) and the electron temperature of 6 eV. The gas from the discharge vessel was leaked into another vessel through a Schott 8250 glass tube with the inner diameter of 5 mm and the length of 6 cm. Charged particles created in the discharge vessel were effectively recombined on the walls of the glass tube, so that the gas entering the experimental chamber was solely a mixture of neutral hydrogen atoms and molecules. The density of hydrogen atoms in the experimental chamber was measured with a well activated nickel catalytic probe. The H density depended on pressure in the discharge vessel and was between 3 and 19 x 10(20) m(-3.) The nickel catalytic probe was replaced with an identical probe made of stainless steel. After successful activation of the stainless steel surface, the signal due to atomic hydrogen recombination was measured at different pressure. Comparing the results obtained with the nickel probe and the stainless steel disc enabled determination of the recombination coefficient for the reaction 2H --> H(2) on polycrystalline stainless steel surface: gamma = 0.10. (C) 1999 Elsevier Science B.V. All rights reserved.