H2 fluorescence spectrum from 1200 to 1700 A by electron impact: Laboratory study and application to Jovian aurora

A combined experimental study of the fluorescence spectrum of H2 at wavelengths of 1200--1700 A by electron impact and its application to modeling the Jovian aurora have been carried out. Our laboratory data suggest that at 100 eV the relative cross sections for direct excitation of Lyα, Lyman bands (B1Σ+/sub u/-X1Σ+/sub g/), and Werner bands (C1π/sub u/-X1Σ+/sub g/) are 1, 2.3 +- 0.6, and 2.6 +- 0.5, respectively, in conflict with Stone and Zipf's (1972) results for the Werner bands. Cascade from E, F1Σ+/sub g/ states contributes an additional 31% to the B1Σ+/sub u/ state population. It is shown that the most likely fate for the metastable H(22S) atoms produced in the Jovian aurora is collisional quenching to H(22P), and this could add as much as 60% to the predicted Lyα emission. On the basis of detailed atmospheric and radiative transfer modeling, we conclude that the recent IUE and Voyager observations are consistent with precipitation of electrons with energy in the range of 1--30 keV or other energetic particles that penetrate to number densities of 4 x 1010--5 x 1013 cm-3 or column densities of 5 x 1017--2 x 1020 cm-2 in the atmosphere. The globally averaged energy flux and production of hydrogen atoms are 0.5--2 ergs cm-2 and 1--4 x 1010 atoms cm-2 s-1, respectively