Modelling of scrape-off layer biasing experiments

Based on the extended B2-code a method has been developed to simulate electrode as well as divertor biasing experiments. To improve the convergence speed of the code a new implicit discretisation scheme for the potential equation based on the Braginski equations was implemented, incorporating viscosity and pressure gradient effects in the expression for the radial current. The organisation of the article is as follows : In a first paragraph a short introduction about the B2-code and the additional equations that determine the electric field and the currents is given. Paragraph 2 deals with electrode and divertor biasing. Some results are shown. Next, a new discretisation scheme to improve the previous one is discussed.