Experimental study on laser entrance hole closure of hohlraum in ICF

On Shenguang Ⅲ laser facility, 32 laser beams were symmetrically injected a gas-filled hohlraum to create plasma situation which is close to the ignition condition. An X-ray framing camera on the polar station and an X-ray streak camera near the pole were utilized to obtain the temporal and spacial evolution X-ray images of the plasma from the hohlraum wall and near the laser entrance hole (LEH), which were used to analyse the LEH closure feature of the hohlraum with various LEH size. The experimental results clearly demonstrated the evolution of laser spot motion, plasma expanding near the LEH and closure of the LEH, which supplied the foundation to optimize the LEH dimension.