Behaviour of superthermal electrons in the scrape-off layer of DIVA

Superthermal electrons are observed in the scrape-off layer of DIVA. The superthermal electrons discussed in this paper are divided into two groups, high-energy electrons (10 keV – 100 keV) and epithermal electrons (150 eV – 500 eV). The epithermal electrons are studied quantitatively and their loss is shown to be explained by the destruction of magnetic surfaces near the separatrix owing to non-axisymmetric perturbations. The two-dimensional path of the high-energy electrons is studied, and the effects of nonaxisymmetric perturbations on the drift surface are discussed.