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P: Fachverband Plasmaphysik

P 7: Poster

P 7.27: Poster

Montag, 19. März 2007, 16:30–18:30, Poster A

First Results of Heavy Ion Beam Probing at WEGA — •Yurij Podoba¹, Martin Schubert¹, and Alexander Zhezhera² — ¹Max-Planck-Institut fuer Plasmaphysik, Greifswald, Germany — ²Kharkov Institute of Plasma Physics, Kharkov, Ukraine

At the classical stellarator experiment WEGA a Heavy Ion Beam Probe (HIBP) diagnostic is currently being installed and tested. The diagnostic principle is based on the difference of the Larmor radii of highly energetic heavy ions with different ionization states. The presented measurements were carried out injecting a primary 33-keV Na+ beam into a He plasma at a magnetic field strength of 0.45 T. The secondary Na++ beam was detected. Energy analysis yields the electrostatic potential inside the secondary ionization volume with an estimated spatial resolution of about 1.5 cm. The intrinsic temporal resolution is high enough to measure plasma parameters in experiments with modulated heating power. Temporal resolution is limited by the noise level and bandwidth of the amplifiers used in the detection system. First measurement results indicate a positive plasma potential, using the vacuum vessel as the potential reference. This is in reasonable agreement with data from Langmuir probes. The WEGA HIBP is being set up and operated in collaboration with the Institute for Plasma Physics in Kharkov, Ukraine.