LMJ Targets for Nuclear Fusion: Recent Experimental and Theoretical Advances on Redistribution Process, Control of Target Temperature, and Effect of D-T Aging

Review on high repetition rate and mass production of the cryogenic targets for laser IFE

“…Such quality parameters are important to overcome the hydrodynamic instabilities during implosion and to reach the ignition at which a nuclear fusion reaction becomes selfsustaining [2,4,8,13,22,29,35] .…”

“…But routine practice is between 1 and 4 attempts, or even 6 attempts [22,29] , which generally requires several days or a week. As a consequence, we can conclude the following:…”

“…[29], the lifetime of the target produced by the beta-layering technique is only several seconds at T = 18.3 K. This gives rise to additional problems in realizing the experiments with such a degree of perfection and accuracy that is required for ignition-level target performance:…”

“…The beta-layering forms very smooth and uniform solid D–T layers using ‘slow cooling’ and ‘rapid cooling’ protocols [21, 29] . At 0.25 K below the D–T triple point temperature ( K), slow-cooled layers meet the NIF smoothness requirement.…”

“…Here we summarize the literature data related to the beta-layering technique: Long-run beta-layering process at very strict isothermal conditions (target temperature must be controlled down to 1 mK precision) requires about 24 h for one attempt. But routine practice is between 1 and 4 attempts, or even 6 attempts [22, 29] , which generally requires several days or a week. As a consequence, we can conclude the following: The method is not efficient to maintain acceptable tritium inventory (for D–T at 19 K, a characteristic constant of the beta-layering is 27 min and increases with decreasing temperature or with increasing concentration of gas [24] ). The method is not efficient for mass target fabrication for IFE (i.e., beta-layering is one-of-a-kind technique). The method is not efficient for repetition-rate fabrication and delivery of the target because all of the experiments on the NIF or Omega laser facilities require a target precisely located in the center of the target chamber.…”