ned conditions in plasmas that approach those required for practical fusion-power generation. Work on another major approach to fusion energy, called inertial confinement fusion (ICF), has been carried on since the early 1960s. Initial efforts were undertaken in 1961 with a then-classified proposal that large pulses of laser energy could be used to implode and shock-heat matter to temperatures at which nuclear fusion would be vigorous. Aspects of inertial confinement fusion were declassified in the 1970s, but a key element of the work--specifically the design of targets containing pellets of fusion fuels--still is largely secret. Very painstaking work to design and develop suitable targets continues today. At the same time, significant progress has been made in developing high-energy, short-pulse drivers with which to implode millimeter-radius targets. The drivers include both high-power lasers and particle accelerators capable of producing beams of high-energy electrons or ions. Lasers that produce more than 100,000 joules in pulses on the order of one nanosecond (10-9 second) have been developed, and the power available in short bursts exceeds 1014 watts. Best estimates are that practical inertial confinement for fusion energy will require either laser or particle-beam drivers with an energy of 5,000,000 to 10,000,000 joules capable of delivering more than 1014 watts of power to a small target of deuterium and tritium . ...
