Observation of highly disparateK-shell x-ray spectra produced by charge exchange with bare mid-Zions

Abstract

We performed charge exchange experiments with the electron beam ion trap at the Lawrence Livermore National Laboratory and an x-ray calorimeter spectrometer. We compare the relative strength of the high-n Lyman series emission for different combinations of ions and neutral gases. Theoretical predictions show good agreement with experimental data on relative capture cross section as a function of principle quantum number n; however, the few published predictions of the distribution of captures as a function of orbital angular momentum l do not agree with experiments. Our experimental results show that the relative strength of high-n Lyman series emission varies more widely than previous experiments have found and models predict. We find that hardness ratios from charge exchange with helium and molecular hydrogen are more disparate than charge exchange with many-electron neutral species, which is likely due to differences in the relative importance of multi-electron capture. We also find that there is no clear scaling of the hardness ratio with ionization potential of the neutral species, the number of valence electrons in the neutral, or the atomic number of the ion.

Imaging Plasma Density Structures in the Soft X-Rays Generated by Solar Wind Charge Exchange with Neutrals

“…While some important emission lines like O 6+ and O 7+ have been reasonably well characterized, many others that contribute to the emissions with energies < 500 eV that are relevant to imaging solar wind interactions with the planetary objects are not (see Smith et al 2014, for a discussion of alternative methods). Beiersdorfer et al (1999Beiersdorfer et al ( , 2000Beiersdorfer et al ( , 2001Beiersdorfer et al ( , 2003, Wargelin et al (2008), Greenwood et al (2001), Mawhorter et al (2007), and Betancourt-Martinez et al (2014) present some relatively recent experimental measurements of X-ray emissions generated by charge exchange. (See also the review within Krasnopolsky et al 2004.)…”

LABORATORY MEASUREMENTS COMPELLINGLY SUPPORT A CHARGE-EXCHANGE MECHANISM FOR THE “DARK MATTER” ∼3.5 keV X-Ray LINE

“…Moreover, CX has been recognized as essential for understanding the ionization equilibrium of laboratory plasmas, and it also affects the storage time in ion traps and the energy transport mechanism in the edge region of tokamak fusion plasmas (Beiersdorfer et al 2000;Leutenegger et al 2010). This has motivated a number of CX studies at the LLNL electron beam ion trap (EBIT) group (Beiersdorfer et al 2000Wargelin et al 2005;Leutenegger et al 2010;Betancourt-Martinez et al 2014) Xue et al 2014), with X-ray spectral analysis carried out at both low and high resolution. Various theoretical models have been invoked for data analysis.…”

Charge exchange, from the sky to the laboratory: A method to determine state‐selective cross‐sections for improved modeling

“…While acx and spex‐cx use different databases for the radiative cascade, it is the initial nl distribution of captured electrons that has the dominant impact on the resulting spectrum—in particular, the l distribution, which is highly velocity‐dependent (Beiersdorfer et al ; Betancourt‐Martinez et al ; Mullen et al ). The acx and spex‐cx models provide good fits to certain observations of SWCX (L. Gu et al ; Smith et al ), but they fail to reproduce some laboratory measurements of CX in the low‐velocity regime (Betancourt‐Martinez et al ).…”