HYDROGEN-ATOM DETECTION BY H(-) CONVERSION

Surface ionization on a commercially available barium oxide converter has been used to find the total beam intensity in the forward directio n of hyperthermal hydrogen atoms dissociated by an arc discharge. The H- ions are selected by a mass spectrometer and measured by a Faraday cup in a high vacuum system. A Monte Carlo simulation is used to calcu late the H- yield of low-energy atoms perpendicularly reflected from t he converter as a model for atom-surface ionization. A beam intensity of approximately 4 X 10(17) atoms/sr s is found by means of the calcul ated H- yield and the measured H- current. The results of this experim ent are compared with the characterization of the same atom beam achie ved by other methods and similar atom beams published in recent litera ture.