<title>Effects of H<formula><inf><roman>2</roman></inf></formula>O on atomic hydrogen generation in hydrogen plasma</title>

Water vapor added hydrogen gas is discharged by microwave. Concentrations of hydrogen atoms are measured in the plasma by actinometry and in the downstream by electron spin resonance (ESR). When water vapor is added to hydrogen gas, the concentration of hydrogen atoms in the plasma increases to an amount three times greater than that of pure hydrogen gas and the concentration in the downstream increases to an amount 90 times greater. When hydrogen gas without water vapor is discharged, the concentration of hydrogen atoms decreases just after the discharge is turned on. When water vapor is added to hydrogen gas, however, this time dependence of hydrogen concentration is not observed.