Measurements of spatial structure of plasma potential and density fluctuations by multichannel heavy ion beam probe on large helical device

Heavy ion beam probe (HIBP) on large helical device is currently equipped with three channel detectors, which can observe three spatial points simultaneously inside the plasma with resolution of ∼10 mm. The beam trajectories and observation point location are calculated numerically and optimized allowing for the identification of the mode structure in multichannel (up to 9) HIBP measurements. The calculations show that the radial and poloidal wavenumbers can be identified by proper changing and choosing of the beam energy and trajectory.