A new fuel compression method for a fast ignition scheme is discussed. To form a high areal density fuel plasma for the ignition condition, homogenous isentropic compression (HIC) with solid spherical target is effective. We improve a multi-step pulse shape method that uses progressive shockwaves and reflected shockwaves for the compression, where a precisely controlled step-pulse laser drives the shockwaves to compress the fuel and suppress entropy increase. Another advantage of this approach is the relatively smooth high dense fuel is distributed at maximum compression time, compared to our previous design based on Kidder's HIC method. In addition, we insert a power dip as a preconditioning before the last pulse step to reduce the electron and ion temperature near critical density. As a result, an optimum implosion is designed using 245 kJ of implosion laser energy to meet the ignition condition.
This paper presents a new fuel compression method for fast ignition fusion. It uses a multi-step pulse shape and precisely controlled shockwaves to isentropically compress the fuel, forming a high-density core suitable for ignition. The approach aims to create a smooth, high-density fuel distribution at maximum compression, improving on previous designs.