Application of multigrid energy analyzer to the scrape-off layer plasma in DIVA

A multigrid energy analyzer was used to measure the ion temperature in the scrape-off layer of DIVA, where the plasma parameters were relatively high, i.e. electron and ion temperatures T sub(e) and T sub(i) <= 60 eV; electron density n sub(e) <= 5 x 1012 cm-3; heat flux q <= 2 kW/cm2. It was found that to obtain the true ion temperature, the bias voltage V sub(E) of the entrance apertures of the analyzer must be chosen so as to satisfy the criterion e+V sub(S) - V sub(P)+<<T sub(i), where V sub(S) and V sub(P) are the plasma potentials before and after the entrance apertures, respectively. The data were consistent with those obtained by other methods, i.e. the Doppler broadening of impurity lines and the Katsumata probe (ion-sensitive probe). (author)