Pulse radiolysis studies of ion–electron recombination in helium. Pressure and temperature effects

Abstract

Using pulse radiolysis techniques, rates of recombination of electrons with Het ions in the presence of helium over a wide pressure range (40-900 Torr) and at temperatures of 200, 235, 275, and 295 K were measured. Two-and three-body recombination processes were resolved, and a temperature dependence for the three-body recombination rate constant of T(;;;.2.9± 1.2) observed. This result agrees well with theoretical predictions of a temperature expo~ent of -2.5 by Bates and Khare and Pitaevskii, and remarkably well with recent work by Cao and Johnsen which gave a temperature exponent of -2.9 for the rate constant for three-body recombination of electrons with simple molecular ions in the presence of helium.

Ignition and afterglow dynamics of a high pressure nanosecond pulsed helium micro-discharge: I. Electron, Rydberg molecules and He (23S) densities

“…However, the recombination rate of electrons becomes highly sensitive to the electron temperature only for < T 0.2 eV e and we can then compare our apparent recombination coefficient with literature values. Sonsbeeck et al [47] and Hofland et al [48] investigated electron recombination in helium for a pressure range compa rable with our work. Pressure is a factor of importance, as with increasing pressure threebody recombination becomes a sig nificant recombination mechanism.…”

A sextupole ion beam guide to improve the efficiency and beam quality at IGISOL

“…Here n 0 is the initial density defined by (Q/α) 1/2 , t represents an evolution time within the ion guide and α is the recombination rate coefficient of helium [30]. The fit to the data in Fig.…”

Collisional–radiative modelling of a helium microwave plasma in a resonant cavity

“…For neutral-assisted recombination of He + 2 ions (process 24 in table 1), we will show that the rate constant for this process is probably weak compared with ambipolar diffusion, indicating that the temperature dependence given by [9] is probably not valid at high temperature. In a recent work [33], Sonsbeek et al show over a limited range of gas temperatures (from 200 to 295 K) that the temperature dependence of the neutral-stabilized recombination of He + 2 is given by 1.60 × 10 −27 (T g /300) −2.9±1.2 . The rate constant decreases with the temperature in agreement with some theoretical predictions but contrary to the dependence given in [9,10].…”