FRAGMENTATION AND STOPPING OF HEAVY CLUSTER IONS IN A LITHIUM TARGET - APPLICATION TO TARGET IMPLOSION

Heavy-ion clusters are considered for driving directly a pellet for inertial confinement fusion. They are shown to be effective at much lower energy than requested for heavy atomic ions. Multifragmentation, arising from a Coulomb explosion, in the target, is discussed with a maximum entropy hypothesis. Direct driving pressure imparted to a deuterium-tritium (DT) pellet is estimated through the ion debris range in the target. The correlated stopping of N ions flowing close to the initial projectile trajectory is seen to be much larger than the uncorrelated one. Specific attention is paid to a few regular geometrics of cluster ion debris stopped in a lithium pusher. The calculations elaborate on the very high driving pressure obtained, for the case of a solid-state density of cluster ion projectiles around the pellet (moving tamper). A target containing 4 mg of deuterium and tritium fuel is demonstrated to be thus imploded in 5 nsec. A driving pressure of 500 Mbars yields an energy output of 630 MJ. This result can be obtained with an initial cluster kinetic energy smaller than 20 keV/amu.