First HIBP results on the WEGA Stellarator

The heavy ion beam probe (HIBP) is an established non perturbing diagnostic for measuring the spatial distributions of plasma potential, density, temperature and poloidal magnetic field (axial current) of magnetically confined fusion plasma. These are determined from the change in the primary ion beam parameters (charge, intensity and trajectory) passing through a plasma volume due to collisions with electrons and interactions with the confining magnetic field. A heavy ion beam probe plasma diagnostic system has been installed and tested on the WEGA stellarator in Greifswald, Germany in 2006–2007. The WEGA HIBP operates with a beam of singly charged sodium ions with an energy of up to 60 keV, ion current up to 100 μA, and beam diameter of 5–6 mm in the confined plasma region. Plasma experiments with the HIBP diagnostic system were carried out at a magnetic field strength of B0 = 0.489 T. In the experiments, an argon plasma was heated with ECRH at 28 GHz. In this work the first plasma potential and total c...