In-vessel visible inspection system on KSTAR

Abstract

To monitor the global formation of the initial plasma and damage to the internal structures of the vacuum vessel, an in-vessel visible inspection system has been installed and operated on the Korean superconducting tokamak advanced research (KSTAR) device. It consists of four inspection illuminators and two visible/H-alpha TV cameras. Each illuminator uses four 150 W metal-halide lamps with separate lamp controllers, and programmable progressive scan charge-coupled device cameras with 1004 x 1004 resolution at 48 framess and a resolution of 640 x 480 at 210 framess are used to capture images. In order to provide vessel inspection capability under any operation condition, the lamps and cameras are fully controlled from the main control room and protected by shutters from deposits during plasma operation. In this paper, we describe the design and operation results of the visible inspection system with the images of the KSTAR Ohmic discharges during the first plasma campaign.

Observation of thermal quench induced by runaway electrons in magnetic perturbation

“…The loss of runaway electrons was inferred by measuring the ex-vessel radiation (XVR) [17], consists mainly of neutrons and hard x-rays. The infrared (IR) and visible cameras [18][19][20] were used to check the spatial distribution of the runaway electrons in the plasma before the loss, and to find the evidence of the runaway-induced radiative cooling, respectively. Locations and field-of-views (FoV) of each diagnostic are schematically shown in figure 2, and brief descriptions of the feature of each diagnostic are listed as below.…”

A small, novel, remote in-vessel inspection system for the Alcator C-Mod tokamak

“…Additionally, the compact nature of the device, large toroidal field coils, external support structure and cryostat require the small number (10) of horizontal ports to be long radially and narrow toroidally (∼ 1m by ∼ 0.1m) with smaller vertical ports with similar aspect ratio. Therefore, unlike other tokamaks [8], only a small toroidal field of view is available from each of the limited number of protection cameras leaving much of the tokamak interior unmonitored. Furthermore, the lack of a dedicated illumination source limits the observational periods to operation with a plasma.…”