Charge-Transfer Cross Sections of Ground State He⁺Ions in Collisions with He Atoms and Simple Molecules in the Energy Range below 4.0 keV

Abstract

Charge-transfer cross sections of the ground state He + ions in collisions with He atoms and simple molecules (H 2 , D 2 , N 2 , CO and CO 2) have been measured in the energy range of 0.20 to 4.0 keV with the initial growth rate method. Since previously published experimental data are scattered in the low energy region, the present observations would provide reasonably reliable cross section data below 4 keV. The charge transfer accompanied by dissociation of product molecular ion can be dominant at low energies for molecular targets. In He + + D 2 collisions, any isotope effect was not observed over the present energy range, compared to H 2 molecule.

Charge Exchange Cross Sections for Noble Gas Ions and N2 between 0.2 and 5.0 keV

“…The charge exchange cross sections for the noble gas ions and neutral N 2 are shown in Figure 2a-d. The He + +N 2 reaction has been studied across a wide energy range [11,[16][17][18][19][20][21]. All seven previous results shown in Figure 2a utilized a gas cell or similar apparatus, and all but Rudd et al [16] and Koopman [19] were able to measure both the charged and neutral components of the ion beam post-charge exchange (CX).…”

“…Charge exchange between ions and neutrals is an important process in a number of fields including fusion science [1], astrophysics [2][3][4][5], and atmospheric physics [6][7][8]. Recently, charge exchange between stellar wind ions (H + , He + , He 2+ ) and molecules has been investigated because of its relevance in astronomy e.g., with CO and CO 2 present in cometary atmospheres [9,10] and N 2 present in planetary atmospheres [11]. The charge exchange process is written…”

“…This is illustrated in particular by collisions between N 2 and atmospheric ions H + and O + in the summary of [7]. In the case of the He + -N 2 reaction, discrepancies still remain between a variety of experimental efforts [11,[16][17][18][19][20][21], including as much as a factor of three in magnitude and qualitatively different behaviors as a function of collision energy.…”

Charge Transfer Cross Sections of Slow Multiply Charged Neon Ions in Collisions with Noble Gas Atoms

“…The charge transfer cross sections were determined from the slope of the linear part of the observed fraction curves. The detection efficiencies of the present MCP-PSD for Ne q+ and neutral Ne particles are assumed to be identical within the experimental uncertainties over the present collision energy range, as discussed in the previous studies [12][13][14]. The vacuum system was evacuated with two turbo molecular pumps (50 and 500 l/s) and a cryogenic pump.…”

Charge-Transfer Cross Sections of Slow Doubly and Triply Charged Carbon Ions from CO and CO₂Molecules

“…The cross sections of charge transfer were determined on the basis of an initial growth rate method: that is, the cross sections were determined from the slope of the linear part of the observed fraction curves for product carbon ions and atoms formed in charge-transfer collisions versus the target gas thickness. It is assumed that the detection efficiencies of the present MCP-PSD for C 3+ , C 2+ , C + and C particles are identical within the experimental uncertainties over the present collision energy range, as discussed in previous studies [10][11][12]. The vacuum system was evacuated with two turbo-molecular pumps (50 and 500 l/s) and a cryogenic pump.…”