Electron gyroharmonic effects in ionization and electron acceleration during high-frequency pumping in the ionosphere
2006 (English)In: Physical Review Letters, ISSN 0031-9007, Vol. 97, no 19, 195002- p.Article in journal (Refereed) Published
Optical emissions and incoherent scatter radar data obtained during high-frequency electromagnetic pumping of the ionospheric plasma from the ground give data on electron energization in an energy range from 2 to 100 eV. Optical emissions at 4278 angstrom from N-2(+) that require electrons with energies above the 18 eV ionization energy give the first images ever of pump-induced ionization of the thermosphere. The intensity at 4278 angstrom is asymmetric around the ionospheric electron gyroharmonic, being stronger above the gyroresonance. This contrasts with emissions at 6300 angstrom from O(D-1) and of electron temperature enhancements, which have minima at the gyroharmonic but have no apparent asymmetry. This direct evidence of pump-induced ionization contradicts previous indirect evidence, which indicated that ionization is most efficiently produced when the pump frequency was below the gyroharmonic.
Place, publisher, year, edition, pages
2006. Vol. 97, no 19, 195002- p.
IdentifiersURN: urn:nbn:se:uu:diva-153398DOI: 10.1103/PhysRevLett.97.195002ISI: 000241960900045OAI: oai:DiVA.org:uu-153398DiVA: diva2:416697