The National Ignition Facility (NIF), proposed by the Office of Inertial Confinement Fusion (ICF), will be used to demonstrate fusion ignition in a laboratory environment (1). The primary mission of NIF will be to support U.S. DOE Defense Programs. The facilities' secondary mission will be to support development of inertial fusion as a potential fusion energy source for civilian use (2). Target insertion is one of the technical issues which will need to be addressed before inertial fusion can become a practical energy source, and is one of the issues that can be investigated by experiments on the NIF.

Target insertion systems currently utilized at existing ICF facilities consist of mechanisms inside the target chamber to insert, position, and hold the target at the chamber center. These are not suitable for multiple shots in quick succession, as needed for energy applications. A study was performed to investigate various new techniques for target insertion in NIF.

Insertion concepts involving free-falling and artificially accelerated targets were developed and evaluated against a set of predetermined guidelines. Fixed structure holding systems were not considered due to the destructive environment at the chamber center. Conclusions drawn by the author suggest a system involving a fast retraction positioner would be suitable. A target would be positioned in a holder attached to a moveable arm. The holder is moved to a position slightly above the chamber center. The target is dropped and the holder/arm assembly is quickly retracted to avoid ablation effects. To improve target accuracy, a release system imparting near-zero torque and augmenting the target with additional mass to reduce drag effects would be employed. A plan illustrating a reasonable continuation of the project, leading ultimately to tests in NIF, is also presented.