Laser blow-off system

To study impurity transport in the main and divertor plasmas by active injection of metal impurity with a laser blow-off.

[Detectors, Diagnostic Method]
High power light from a YAG laser is transferred to a two-lens condenser using a optical fiber light guide with a large diameter quartz fiber. The focused laser spotlight is irradiated metal targets, which are installed inside the JT-60U vacuum vessel. The metal target is evaporated and its vapor is injected to the main and divertor plasmas by absorption of the injected laser energy.

„YAG laser: Max. 70 J/pulse (duration:10 ms), 1-50 pulses/sec
„Fiber light guide : Quartz fiber, core diameter of 0.4 mm (GI) and 0.6 mm (SI)
„Position: P-18 section, IN-1A-a port (to the main plasma)
:P-6 section, R-3-b port (to the divertor plasma)
„Targets: 1 position (midplane), size 50x10x10 mm/piece, material Al, Ti, Fe, Ni, Mo, W,SUS (main)
3 positions (inner divertor plate, inner baffle plate, dome), size 20x20x19 mm/piece, material Al, Ti, Fe, Ni (divertor)

(1) A. Matsunawa et al., "Laser Production of Ultra-Fine Metal Particles", Kouon Gakkai-shi, Vol. 13, No. 1, 30 (1987), in Japanese.