2D spatial profile measurements of potential fluctuation with heavy ion beam probe on the Large Helical Device

Two-dimensional spatial profiles of potentialfluctuation weremeasured with theheavy ion beam probe (HIBP) in theLarge Helical Device(LHD). For 2D spatial profilemeasurements, the probebeam energy has to be changed, which requires the adjustment of many deflectors in thebeam transport line to optimize thebeam trajectory, since the transport line of LHD-HIBP system is long. The automaticbeam adjustment system was developed, which allows us to adjust thebeam trajectory easily. By analyzingcoherence between potentialfluctuation and magnetic probe signal, the noise level of the mode power spectrum of the potentialfluctuation can be reduced. By using this method, the 2D spatial profile of potentialfluctuation profile was successfully obtained.

Source: Review of Scientific Instruments - October 18, 2016 Category: Physics Authors: A. Shimizu, T. Ido, M. Nishiura, S. Kato, K. Ogawa, H. Takahashi, H. Igami, Y. Yoshimura, S. Kubo and T. Shimozuma Source Type: research