High-resolution X-ray imaging in fast ignition experiment using Gekko and LFEX lasers

M Koga,H Shiraga,T Sogo,H Azechi,S Fujioka,Y Ishii,K Shigemori,P Mora,E Moses,K A Tanaka

doi:10.1051/epjconf/20135903006

Abstract

We improved diagnostic instruments to measure X-ray images in a hard X-ray harsh environment and succeeded in obtaining clear images with X-ray framing camera and X-ray streak camera in fast ignition experiment conducted in 2011 (FG-02 Experimental Campaign). We found that high-energy X-ray signals could be used as an indicator of the LFEX laser injection time relative to the imploded core. The LFEX laser injection time was estimated with better than 10 ps accuracy. Time-resolved 2D X-ray images suggested that shapes and motions of imploded core plasmas were improved by changing the configuration of the implosion lasers.

Highlights

Fast ignition [1,2,3,4] is one of the methods of achieving laser fusion
We found that high-energy X-ray signals could be used as an indicator of the LFEX laser injection time relative to the imploded core
The size of the imploded core plasma becomes less than 100 micron and its heating process lasts only less than 100 ps

Summary

INTRODUCTION

Fast ignition [1,2,3,4] is one of the methods of achieving laser fusion This scheme separates lasers into two systems: one for implosion and the other for heating the imploded fuel core. In the fast ignition experiment, hard X-rays above 100 keV were generated from hot electrons through bremsstrahlung [5]. These X-rays caused many troubles, such as malfunction of control devices, intense signal overlaps (See Fig. 1(a)) and cathode discharges (See Fig. 2(a)). We report our improvements to overcome such a harsh environment and obtained results

EXPERIMENTAL SETUP

Measurements in a harsh environment

Control of the imploded core plasma using 12 laser beams