Lα emission from collisional excitation of H Atoms by threshold energy Ar+ ions

In a specially designed collision chamber, H atoms produced by a microwave discharge were excited into the 2 p state by impact of Ar⁺ ions in a beam. A degree of dissociation up to η=94% was measured at the exit of the microwave source, although in the center of the collision cell η is smaller, with a lower limit of 33 %. The effect of vibrational excitation of H2 by the discharge and the resulting difficulties of measuring η are discussed. The cross section for Lα emission increases linearly from the threshold, at 10.2 eVCM, to 17.1 eVCM. The absolute cross section at this energy is 1.5·10^-17 cm² for η=33% (with a minimum of 0.6·10^-17 cm², for the maximum possible η). The absence of an activation barrier rules out some features shown by an earlier ab initio calculation. © 1985 Springer-Verlag.

Duke Scholars

Author Berndt Mueller Physics