G C Angel

Ionization and charge transfer in fast H+-He+ collisions using an intersecting beam technique

A fast intersecting beam technique has been used to obtain total cross sections sigma (He2+) for He2+ formation from the combined processes H++He+ to H++He2++e (ionization) and H++He+ to H+He2+ (charge transfer) in the centre-of-mass energy range 72-402 keV. At these energies, ionization is believed to provide the main contribution to the measured cross sections which are shown to be in good agreement with cross sections for ionization predicted theoretically by scaling data for H+-H collisions. Values of sigma (He2+) also show the expected tendency to converge to corresponding cross sections for ionization by electron impact at high equivalent velocities.

The velocity distribution of atoms issuing from a multi-channel glass capillary array and its implication on the measurement of atomic beam scattering cross sections

The velocity distribution of caesium atoms issuing from a multi-channel glass capillary array has been studied and an energy-exchange process proposed to account for the modification to a Maxwellian distribution. The importance of knowing the exact distribution in the measurement of atomic beam total scattering cross sections is indicated by the calculation of the appropriate kinetic averaging factors.

Charge transfer and ionisation in fast H+-He+ collisions: further measurements using a coincidence technique

A coincidence technique has been used in a fast intersecting beam study of H+-He+ collisions to determine cross sections for charge transfer in the centre-of-mass energy range 60-180 keV. Cross sections for ionisation have also been determined by reference to previously measured total cross sections for He2+ production from the combined processes of charge transfer and ionisation.

Ionisation and charge transfer in fast H+-Li+ collisions

A fast intersecting beam technique previously developed in this laboratory has been applied to study H+-Li+ collisions at centre-of-mass energies in the range 62-350 keV. Total cross sections for the production of Li2+ from the combined processes of charge transfer and ionisation have been determined. A coincidence technique has also been used to obtain the separate cross sections for these processes which are compared with current theoretical predictions.

An experimental study of charge transfer and ionisation in Cs+-Cs+ collisions

Cross sections for Cs2+ production from the combined processes of charge transfer and ionisation in Cs+-Cs+ collisions have been determined at centre-of-mass energies between 40 and 280 keV using an intersecting-beam technique previously developed in this laboratory. Measured cross sections are at least 1.5*10-16 cm2 and the results are directly relevant to proposed schemes for heavy-ion fusion.

Charge transfer and ionisation in collisions between Li+ ions

Cross sections for the combined processes of charge transfer and ionisation in Li+-Li+ collisions have been determined using an intersecting beam technique for CM energies in the range 53-240 keV. The results are compared with the previous experimental measurements of Peart et al. (1981) spanning the range 19-88 keV and with theoretical predictions. The latter form the basis of models used to describe collisions between much heavier ions of relevance to heavy-ion fusion.

Charge transfer and ionisation of H+-C+ and H+-N+ collisions

An intersecting beam technique has been used to determine cross sections for C2+ and N2+ production from the combined processes of charge transfer and ionisation in H+-C+ and H+-N+ collisions at CM energies ranging from 65 keV to 470 keV. Ionisation is believed to provide the main contribution to the measured cross sections. Results are compared with other relevant data and considered in terms of a simple classical scaling relation.

Charge transfer and ionisation in collisions of protons with Al+, Ga+ and Tl+ ions

An intersecting beam technique has been used to study charge transfer and ionisation in collisions of protons with Al+, Ga+, In+ and Tl+ ions at centre-of-mass energies in the range 50-597 keV. Total cross sections for the combined processes of charge transfer and ionisation have been determined. Separate measurements have also been made of cross sections for charge transfer alone so that cross section for ionisation could then be derived. The results are considered in relation to other relevant experimental data and theoretical predictions where available.