Hollow shell pellets have been imploded uniformly by the Gekko12 laser system to be compressed to several hundreds g/cm3. The compressed density has been measured both by the neutron activation methods and the electron degeneracy measurement. The densities given by the two methods are consistent. The target parameter dependences of the density are analyzed with the one dimensional implosion simulation code. Except the case of high convergence ratio implosion, the compressed plasma density obtained by the simulation code with nonlocal heat transport and/or high energy electron preheating agrees with the experimental results. As for the high convergence implosion, the one dimensional simulation does not give good prediction of the implosion, in particular for the neutron yield. Actually, the experimental neutron yield for the convergence ratio higher than 20 is lower by more than two orders of magnitude than the simulation value.
High-convergence uniform implosion of fusion pellets with the new GEKKO laser