Investigation of excitation and ionization excitation of He following electron and proton impact using EUV polarimetry

Hocine Merabet; Annette Siems; Reinhard F. Bruch; Jonathan Hanni; Matthew Bailey; Hsiang-Chi Tseng; Chii-Dong Lin; Antonio Gomes Trigueiros

doi:10.1117/12.410547

18 December 2000 Investigation of excitation and ionization excitation of He following electron and proton impact using EUV polarimetry

Hocine Merabet, Annette Siems, Reinhard F. Bruch, Jonathan Hanni, Matthew Bailey, Hsiang-Chi Tseng, Chii-Dong Lin, Antonio Gomes Trigueiros

Author Affiliations +

Proceedings Volume 4139, Instrumentation for UV/EUV Astronomy and Solar Missions; (2000) https://doi.org/10.1117/12.410547
Event: International Symposium on Optical Science and Technology, 2000, San Diego, CA, United States

Abstract

A detailed investigation of excitation of He (1s²) ¹S to He (1snp) ¹P degree(s) (n equals 2 - 5) states and ionization-excitation of He (1s²) ¹S to He (2p) ²P degree(s) and He (3p) ²P degree(s) states in e^- + He and H⁺ + He collision systems is presented for a wide range of projectile velocities (2.2 a.u. < v < 6.9 a.u.). Specifically new experimental data are presented on measurements of the degree of linear polarization for excitation and excitation-ionization of He following proton impact in the extreme ultraviolet (EUV) wavelengths. These measurements have been performed using a characterized molybdenum/silicon multilayer mirror polarimeter (MLM) whose polarization characteristics have been optimized for EUV emission of He and He⁺. Furthermore, the proton experimental results are compared with theoretical polarization data using the first Born approximation and recent atomic orbital close coupling (AOCC) calculations for the excitation process. A comprehensive comparison of experimental data for negatively and positively charged projectiles at equal impact velocities is also given in order to elucidate differences in the collision mechanisms of two electron targets. It is important to note that these results are relevant for astrophysical diagnostics such as solar flares.

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Hocine Merabet, Annette Siems, Reinhard F. Bruch, Jonathan Hanni, Matthew Bailey, Hsiang-Chi Tseng, Chii-Dong Lin, and Antonio Gomes Trigueiros "Investigation of excitation and ionization excitation of He following electron and proton impact using EUV polarimetry", Proc. SPIE 4139, Instrumentation for UV/EUV Astronomy and Solar Missions, (18 December 2000); https://doi.org/10.1117/12.410547

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