Collisional-radiative transfer between Rydberg states of helium and electronic recombination of He/sup +/

Journal Article · Fri Apr 01 04:00:00 EST 1977 · Phys. Rev., A; (United States)

DOI:https://doi.org/10.1103/PhysRevA.15.1502· OSTI ID:7120289

Boulmer, J; Devos, F; Stevefelt, J; Delpech, J

We report detailed spectroscopic measurements of light emission and excited level populations in a pure-helium afterglow at a presssure of 2.03 Torr. The free-electron temperature could be varied by microwave heating. Electron density n/sub e/ and temperature T/sub e/ were measured by precision microwave interferometry and they range from 5 x 10/sup 9/ to 3 x 10/sup 11/ cm/sup -3/ for n/sub e/ and from 300 to 600 degreeK for T/sub e/. Rydberg states of neutral helium near the bottleneck for collisional-radiative (CR) recombination were perturbed in a well-controlled manner by photoionization with 10.6-..mu..m photons. Our experimental data are consistent with a CR recombination scheme with simultaneous stabilization by collisions with free electrons and with neutral helium atoms. They establish the fact that the Gryzinski formalism for electron-impact--induced transitions between bound Rydberg states of high principal quantum number seriously overestimates the probability of collisions with small energy transfers. This study gives also experimental indications of what appears to be neutral-stabilized CR recombination of an atomic ion, He/sup +/. The experimental recombination rate coefficient is well represented over the range of parameters covered at rate coefficient is well represented over the range of parameters covered at 2.03 Torr by ..cap alpha.. (cm/sup 3/ sec/sup -1/) = 3.5 x 10/sup -5/ T/sub e//sup -1//sup .//sup 9/ + 6.0 x 10/sup -9/ T/sub e//sup -2//sup .//sup 18/ n/sub e//sup 0//sup .//sup 37/ + 3.8 x 10/sup -9/ T/sub e//sup -4//sup .//sup 5/ n/sub e/, in reasonable agreement with available theories.

• Research Organization: Groupe d'Electronique dans les Gaz, Institut d'Electronique Fondamentale, Batiment 220, Universite Paris-XI, Centre d'Orsay, 91405 Orsay, France
• OSTI ID: 7120289
• Journal Information: Phys. Rev., A; (United States), Journal Name: Phys. Rev., A; (United States) Vol. 15:4; ISSN PLRAA
• Country of Publication: United States
• Language: English

Related Subjects

640304* -- Atomic
Molecular & Chemical Physics-- Collision Phenomena
74 ATOMIC AND MOLECULAR PHYSICS
COLLISIONS
CRYOGENIC FLUIDS
ELECTRON COLLISIONS
ELECTRON-ION COLLISIONS
ELEMENTS
ENERGY LEVELS
ENERGY-LEVEL TRANSITIONS
EXCITED STATES
FLUIDS
HELIUM
HELIUM IONS
ION COLLISIONS
NONMETALS
RARE GASES
RECOMBINATION