Toward a full exploitation of the helium beam edge diagnostic.

In this article, extension of the He beam diagnostic, which is routinely applied in fusion devices for the characterization of the edge electronic parameters—ne and Te—and their profile, to the measurement of ion temperature and plasma rotation is proposed. The theoretical background for these new applications is reviewed and examples of their use in TJ-II are provided. Also, the shortcomings and their possible solutions are addressed. Finally, the field of application of the technique to other beam-based diagnostics is discussed.