Inertial confinement fusion

From top, left to right

1. A deuterium-tritium target pellet
2. A depiction of the hohlraum absorbing lasers and emitting X-rays
3. The target chamber interior of the National Ignition Facility, US
4. The NIF laser bay
5. The target chamber of Shiva at LLNL, US
6. The target chamber of Orion, UK
7. Diagram of Helios, an early LANL experiment
8. Diagram of LIFE, an LLNL ICF power plant concept
9. The 2022 NIF announcement of the first fusion energy gain factor greater than one

Inertial confinement fusion (ICF) is a fusion energy process that initiates nuclear fusion reactions by compressing and heating targets filled with fuel. The targets are small pellets, typically containing deuterium (²H) and tritium (³H).

Typically, short pulse lasers deposit energy on a hohlraum. Its inner surface vaporizes, releasing X-rays. These converge on the pellet's exterior, turning it into a plasma. This produces a reaction force in the form of shock waves that travel through the target. The waves compress and heat it. Sufficiently powerful shock waves achieve the Lawson criterion for fusion of the fuel.

ICF is one of two major branches of fusion research; the other is magnetic confinement fusion (MCF). When first proposed in the early 1970s, ICF appeared to be a practical approach to power production and the field flourished. Experiments demonstrated that the efficiency of these devices was much lower than expected. Throughout the 1980s and '90s, experiments were conducted in order to understand the interaction of high-intensity laser light and plasma. These led to the design of much larger machines that achieved ignition-generating energies. Nonetheless, MCF currently dominates power-generation approaches.

Unlike MCF, ICF has direct dual-use applications to the study of thermonuclear weapon detonation. For nuclear states, ICF forms a component of stockpile stewardship. This allows the allocation of not only scientific but military funding.^[1]

California's Lawrence Livermore National Laboratory has dominated ICF history, and operates the largest ICF experiment, the National Ignition Facility (NIF). In 2022, an NIF deuterium-tritium shot yielded 3.15 megajoules (MJ) from a delivered energy of 2.05 MJ, the first time that any fusion device produced an energy gain factor above one.^[2][3]