Escaping ion measurement with high time resolution on CHS

Shinohara, Koji; Isobe, Mitsutaka*; Darrow, D. S.*

A scintillator probe can measure the temporal evolution of both the gyro-radius and the pitch angle of the escaping ions with relatively large energy. On this system, the time resolution of the 2D measurement is determined by a framing rate of the camera. The framing rate of the old camera was 60Hz, thus the time resolution was about 17 ms. Our interest is to understand the energetic ion transport in fast events such as a bursting Alfvn eigenmode. The typical time scale of these event interested is less than a few ms. The time resolution of the old camera was not enough for this purpose. The FASTCAM ultima II, which is a product of Photron Co., is an image-intensified high-speed video camera system with the ability to record up to 13,500 frames per second. By replacing the old camera with this ultima II, the temporal resolution was improved from about 17 ms to 0.075 ms. We have successfully installed the fast camera and captured some fast events caused by MHDs, which was not observed by the old camera. Here, we will present the specification of this system and the preliminary results using this fast camera.