Accession Number : AD0721462

Title :   Lyman-Alpha Emission Cross Sections for Collision of H(+) and H with N2 and O2,

Corporate Author : AEROSPACE CORP EL SEGUNDO CALIF LAB OPERATIONS

Personal Author(s) : Birely,John H. ; McNeal,R. J.

Report Date : 15 FEB 1971

Pagination or Media Count : 38

Abstract : Cross sections are reported for the emission of Lyman-alpha radiation in collisions of beams of 1 - 30 keV H(+) and H with thin targets of N2 and O2. The observed emission cross sections yield the cross sections for population of H(2p) in electron capture collisions of the protons and in excitation collisions of the hydrogen atoms after small corrections for polarization and cascade effects. Application of an electric field of several hundred V/cm in the collision chamber causes the light emission to be enhanced, owing to radiative quenching of metastable H(2s), and the maximum contribution to emission of auroral Lyman-alpha from production of H(2s) can be assessed. The results show that collisional excitation of fast hydrogen atoms rather than electron capture by protons is the major mechanism for H(2s) and H(2p) production in the aurora. Consideration of the ratio of the cross sections for producing H(2s) and H(2p) and of the possible collisional quenching processes for H(2s) leads to the conclusion that the major contribution to auroral Lyman-alpha in the 1 - 30 keV energy range is emission from hydrogen atoms collisionally excited to the 2p state. (Author)

Descriptors :   (*AURORAE, ULTRAVIOLET RADIATION), (*HYDROGEN, *ELECTRON TRANSITIONS), (*PROTON BOMBARDMENT, *DIATOMIC MOLECULES), UPPER ATMOSPHERE, NITROGEN, HYDROGEN, QUENCHING(INHIBITION)

Subject Categories : Atmospheric Physics
      Physical Chemistry

Distribution Statement : APPROVED FOR PUBLIC RELEASE