WALL TEMPERATURE-DEPENDENCE OF BORONIZATION USING DECABORANE AND DIBORANE

A new boronization technique based on pyrolysis of boron hydrides on h ot walls was investigated in a laboratory experiment. The deposition r ate of boron films through pyrolysis of decaborane was high enough to apply the pyrolysis to actual fusion devices bakable to 300-degrees-C. The hydrogen concentration of boron films prepared by the pyrolysis o r conventional plasma-assisted boronization at various temperatures wa s measured with N-15 nuclear reaction and/or IR absorption methods. Th e hydrogen content markedly decreased with increasing wall temperature , where decaborane always gives higher H content than diborane. Oxygen gettering and hydrogen recycling in a boronized vessel were evaluated by pulsed glow discharge in O2/He and D2, respectively. The results w ere compared between the pyrolysis and the plasma-based boronizations in decaborane or diborane at various wall temperatures.