Heavy ion fusion

rdf:langString Heavy ion fusion

rdf:langString Heavy ion fusion is a fusion energy concept that uses a stream of high-energy ions from a particle accelerator to rapidly heat and compress a small pellet of fusion fuel. It is a subclass of the larger inertial confinement fusion (ICF) approach, replacing the more typical laser systems with an accelerator. Accelerators have the potential to be much more efficient in terms of delivering energy to the fuel pellet; typical laser-based "drivers" have overall efficiency on the order of 1%, while heavy-ion systems aim for 30% or more. Additionally, they can produce pulses of energy many times a second, while existing high-energy laser systems require lengthy cooling periods between "shots". These advantages would be useful in a commercial setting, as they would greatly lower the cost of operation, and somewhat lower the cost of building the plant compared to a laser system. The basic concept had been suggested on occasion before 1970, using either electrons or protons. Fundamental limits on the beam focusing using electrons and stopping distances of protons led to the concept of using heavy ions, whose higher mass allows them to remain more focussed and stop more rapidly. A major meeting in 1976 led to the rapid uptake of the concept through the late 1970s and early 1980s. In the late 1970s, heavy ion fusion (HIF) was described as "the conservative approach" to a working fusion reactor. Further work culminated in the HYLIFE-II design, prepared at the Lawrence Livermore National Laboratory (LLNL) in the early 1990s. Since that time, in spite of continued interest, no large-scale experimental device using the approach has been built. It has the disadvantage that accelerators with the required energies can only be built in a large size, on the order of kilometres, which makes it difficult to test with low-cost systems. In contrast, even small lasers can reach the desired conditions, which is why they remain the focus of the ICF approach.