Collisional-radiative recombination Ar++e

Petr Dohnal¹,

Štěpán Roučka²,

Pavol Jusko³

et al.

Abstract

Rate coefficients for collisional-radiative recombination (CRR) of Ar + ions with electrons have been measured at temperatures from 77 to 180 K in a helium-buffered flowing-afterglow (Cryo-FALP) experiment at electron densities n e from 10 8 to 10 10 cm −3 . The measured ternary rate coefficient K CRR at 77 K is (1.1 ± 0.4) × 10 −17 cm 6 s −1 and the observed variation with temperature agrees well with the theoretical T −4.5 dependence.

Cryo-FALP study of collisional-radiative recombination of Ar+ions at 40–200 K

“…The thermodynamic equilibrium is reached and instead of the temperature of electrons (T e ), ions (T i ) and neutrals (T n ) only one temperature can be used T = T e = T i = T n (for details and discussion on plasma species thermalization in afterglow plasma see refs. [11,[22][23][24]). At the beginning of section B plasma is precooled via collisions with helium buffer gas to 100 -120 K and in section C to the desired temperature adjusted in the range 40 -300K (see discussion later on).…”

“…It is not obvious, that the Stevefelt formula holds also at low temperatures (below 300 K). Only very recently CRR was studied in our laboratory at temperatures below 200 K and K CRR was obtained for temperatures from 77 up to 200 K [11]. Process of CRR has been studied also in ultracold plasmas in connection with formation of neutral antihydrogen, where it is expected that at high positron number density the production of antihydrogen via recombination of positrons with antiprotons can be enhanced by CRR process.…”

Binary recombination of para- and ortho-H 3 + with electrons at low temperatures

“…The possible effects of another ternary process-collisional radiative recombination (CRR) [23,24]-are discussed in detail elsewhere [25].…”

State selective study of H3+recombination in Cryo-FALP and SA-CRDS experiments at 77 K

“…A source of parastate-enriched hydrogen gas (para-hydrogen generator) was also described in our previous publication [12]. The combination of the para-hydrogen generator and Cryo-FALP II allows us to measure the recombination rate coefficients of para-and ortho-H + 3 ions with electrons at temperatures down to 40 K [15,16]. To obtain information on para/ortho H + 3 composition in the afterglow plasma, which is important for evaluation of state specific recombination rate coefficients we measured this composition in parallel SA-CRDS experiment at temperatures 77-300 K [5][6][7]12].…”

“…One of the advantages of plasmatic environment is possibility to study ternary recombination processes assisted by neutrals, by electrons, or eventually by both of them, see Refs. [14][15][16][17] and references therein. In studies of binary recombination of H + 3 ions in He/Ar/H 2 gas mixture it was observed that the decay of afterglow plasma is dependent on He number density [5,6,[18][19][20].…”