Three-dimensional observation system for pellet ablation traveling in the high-temperature plasmas

In order to investigate the ablation of a solid hydrogen pellet, which is injected into a high-temperature plasma with high speed (∼1km∕s) for the plasma refueling, a three-dimensional observation system using a fast camera has been developed. A stereo method has been employed to obtain the three-dimensional information of the pellet ablation. A pair of the stereo images, which have been taken from different locations, has been focused onto a single fast camera by using a bifurcated fiber scope to ensure the simultaneity of both images. The projection matrix, which is used for stereo reconstruction, is calibrated by taking images of a model plane of known coordinates from the actual camera positions. The measuring error of the stereo observation is within 2% in the depth direction.