Polarization measurements of the extreme ultraviolet (EUV) emission following excitation and ionization-excitation of helium by fast electron, proton, and molecular hydrogen (H2+ and H3+) impact

Hocine Merabet; Reinhard F. Bruch; Stephan Fuelling; K. Bartschat; Alexander Godunov; James H. McGuire; A. N. Grum-Grzhimailo

doi:10.1117/12.450401

25 September 2002 Polarization measurements of the extreme ultraviolet (EUV) emission following excitation and ionization-excitation of helium by fast electron, proton, and molecular hydrogen (H₂+ and H₃+) impact

Hocine Merabet, Reinhard F. Bruch, Stephan Fuelling, K. Bartschat, Alexander Godunov, James H. McGuire, A. N. Grum-Grzhimailo

Author Affiliations +

Proceedings Volume 4819, Polarization Measurement, Analysis, and Applications V; (2002) https://doi.org/10.1117/12.450401
Event: International Symposium on Optical Science and Technology, 2002, Seattle, WA, United States

Abstract

We report intensive experimental and theoretical data corresponding to helium extreme ultraviolet (EUV) emission in the 30-60 nm wavelengths range for e^- + He, H⁺ + He, and H_n⁺ + He (n=2-3) collisions with impact velocities from 1.4 to 8.5 a.u. Specifically, the degree of linear polarization associated with HeI (1snp) ¹P^o levels, n=2-5, (λ=51.7 to 58.4 nm for n=2-5 to n=1 transitions) and HeII (2p) ²P^o states (λ=30.4 nm) have been measured at intermediate- to high-energy range using a compact lightweight molybdenum/silicon multilayer mirror polarimeter (MLM). The combination of these polarization measurements with our previous total EUV cross sections has enabled us to determine experimental magnetic substate scattering angle-integrated cross sections σ₀ and σ₁for ML = 0, ±1, and 1 following excitation of He (1s²) 1S to HeI (1s2p) ¹P^o levels and ionization-excitation to He⁺ (2p) ²P^o for electron and proton impact at a wide range velocities. The degree of linear polarization and obtained magnetic sublevel cross sections are compared to earlier theoretical calculations together with our recent 23-state R-Matrix, 1st and 2nd Born calculations. Such a detailed comparison may shed more light on the collision processes involved in positively and negatively single charge particle impact in helium. In particular it shows that electron-electron interactions play an important role in the ionization-excitation mechanism. In addition, this comprehensive database possibly will provide a deeper understanding of electron and proton induced jets in solar flare astrophysical investigations.

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Hocine Merabet, Reinhard F. Bruch, Stephan Fuelling, K. Bartschat, Alexander Godunov, James H. McGuire, and A. N. Grum-Grzhimailo "Polarization measurements of the extreme ultraviolet (EUV) emission following excitation and ionization-excitation of helium by fast electron, proton, and molecular hydrogen (H₂+ and H₃+) impact", Proc. SPIE 4819, Polarization Measurement, Analysis, and Applications V, (25 September 2002); https://doi.org/10.1117/12.450401

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