Spectropolarimetric measurements of the extreme-ultraviolet emission from helium following e-, H+, H2+, and H3+ charged particle impact

Hocine Merabet; Reinhard F. Bruch; Jonathan Hanni; Alexander Godunov; James H. McGuire; Igor Bray; D. V. Fursa; Klaus Bartchat; Hsiang-Chi Tseng; Chii-Dong Lin; Silvano Fineschi

doi:10.1117/12.450057

10 December 2001 Spectropolarimetric measurements of the extreme-ultraviolet emission from helium following e-, H⁺, H2⁺, andH₃ ⁺ charged particle impact

Hocine Merabet, Reinhard F. Bruch, Jonathan Hanni, Alexander Godunov, James H. McGuire, Igor Bray, D. V. Fursa, Klaus Bartchat, Hsiang-Chi Tseng, Chii-Dong Lin, Silvano Fineschi

Author Affiliations +

Proceedings Volume 4498, UV/EUV and Visible Space Instrumentation for Astronomy and Solar Physics; (2001) https://doi.org/10.1117/12.450057
Event: International Symposium on Optical Science and Technology, 2001, San Diego, CA, United States

Abstract

We present here comprehensive experimental data corresponding to helium extreme ultraviolet emission (EUV) for the 300-600A wavelength range in e^- + He, H⁺ + He, and Hn_n⁺ + He (n=2-3) collisions with impact velocities ranging from 1.4 to 6.9 a.u. The degree of linear polarization associated with HeI (1snp) ¹P^o -> (1s²) ¹S decays for n-2-5 ((lambda) =510 to 584A) and HeII (2p) ²P^o -> (1s) ²S transitions ((lambda) =304A), have been measured at intermediate and higher energies. These measurements have been conducted using a compact lightweight molybdenum/silicon multilayer mirror (MLM) spetropolarimeter. These experimental results are compared with our most advanced theoretical calculations using the close coupling method and several many body perturbation approaches. In this study, the degree of linear polarization will be discussed as a function of the projectile charge to elucidate few body excitation and ionization-excitation processes. Specifically, more sophisticated calculations including second Born approximation with full off-energy terms for the HeII (2p) ²P^o sublevels have been used. The excellent agreement with our HeII Lyman-(alpha) data clearly demonstrates that off-energy terms in two-electron atomic interaction have very prominent effects. Our comprehensive experimental and theoretical database is also of great importance for the understanding of solar physics phenomena. Such results can be used as a new diagnostic tool for clarifying the role of electron and proton beams in solar flares.

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Hocine Merabet, Reinhard F. Bruch, Jonathan Hanni, Alexander Godunov, James H. McGuire, Igor Bray, D. V. Fursa, Klaus Bartchat, Hsiang-Chi Tseng, Chii-Dong Lin, and Silvano Fineschi "Spectropolarimetric measurements of the extreme-ultraviolet emission from helium following e-, H⁺, H2⁺, andH₃ ⁺ charged particle impact", Proc. SPIE 4498, UV/EUV and Visible Space Instrumentation for Astronomy and Solar Physics, (10 December 2001); https://doi.org/10.1117/12.450057

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