Gas-mixing: Ion cooling or reduced turbulent heating?

The question posed in the title concerns the explanation of a well-practised technique in ECR ion sources for increasing the output of the highest charge states of the ions of interest. For a long time the most accepted model was that of ion cooling, being a 'single-particle' effect. Two recent papers, likely inspired on earlier work, are proposing a 'collective' effect due to non-linear plasma-wave interaction, giving rise to turbulent heating. The mixing gas will in that picture reduce the heating. A few experiments are suggested to help unravel the problem of stating which effect is dominating.