(Kyle Palmer/PPPL Communications Department)
The Sun at the center of our own Solar System is a great advert for nuclear fusion: ultra-high temperatures and pressures combining to fuse hydrogen nuclei together into helium nuclei, releasing a huge amount of energy along the way. If we can get the same reactions happening on Earth, nuclear fusion has the potential to drive a revolution in abundant, carbon-free energy – but replicating a star inside a science lab is proving as challenging as you might expect. Now, researchers from Princeton University have published a study in Physical Review Letters that details how we might get to nuclear fusion more quickly………Continue reading….
By David Nield
Source: ScienceAlert
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Critics:
Fusion power is a potential method of electric power generation from heat released by nuclear fusion reactions. In fusion, two light atomic nuclei combine to form a heavier nucleus and release energy. Devices that use this process are known as fusion reactors.
Research on fusion reactors began in the 1940s. As of 2025, the National Ignition Facility (NIF) in the United States is the only laboratory to have demonstrated a fusion energy gain factor above one, but efficiencies orders of magnitude higher are required to reach engineering breakeven (a net electricity-producing plant) or economic breakeven (where the net electricity pays for the plant’s whole-life cost).
Thermonuclear fusion reactions require fuel in a plasma state and a confined environment with high temperature, pressure, and sufficient confinement time. The relationship between these parameters is expressed by the Lawson criterion. In stars, gravity provides the conditions for fusing hydrogen isotopes. Experimental reactors use deuterium and tritium, heavier isotopes of hydrogen, in a process known as DT fusion. This reaction forms a helium nucleus and an energetic neutron.
Fusion fuel is extremely energy-dense, but tritium is scarce on Earth and decays with a half-life of about 12.3 years. Future reactors plan to use lithium breeding blankets that generate tritium when exposed to neutron radiation. Fusion offers advantages compared with nuclear fission. It produces minimal high-level radioactive waste and involves lower inherent safety risks. However, the process generates intense neutron radiation that gradually damages the inner walls of a reactor.
Achieving sustained energy gain beyond breakeven and converting it efficiently into electricity remain major technical challenges. Research focuses mainly on two methods: magnetic confinement fusion (MCF) and inertial confinement fusion (ICF). MCF devices use magnetic fields to contain plasma. Early concepts included the z-pinch, stellarator, and magnetic mirror, with the tokamak design becoming dominant after Soviet experiments in the 1960s.
ICF compresses and heats small fuel pellets using high-energy lasers, developed primarily since the 1970s. The largest active projects are ITER in France and the National Ignition Facility in the United States. Commercial and academic teams are also studying alternatives such as magnetized target fusion and modern stellarator designs.
Multiple approaches have been proposed to capture the energy that fusion produces. The simplest is to heat a fluid. The commonly targeted D–T reaction releases much of its energy as fast-moving neutrons. Electrically neutral, the neutron is unaffected by the confinement scheme. In most designs, it is captured in a thick “blanket” of lithium surrounding the reactor core. When struck by a high-energy neutron, the blanket heats up. It is then actively cooled with a working fluid that drives a turbine to produce power.
Another design proposed to use the neutrons to breed fission fuel in a blanket of nuclear waste, a concept known as a fission-fusion hybrid. In these systems, the power output is enhanced by the fission events, and power is extracted using systems like those in conventional fission reactors. Designs that use other fuels, notably the proton-boron aneutronic fusion reaction, release much more of their energy in the form of charged particles.
In these cases, power extraction systems based on the movement of these charges are possible. Direct energy conversion was developed at Lawrence Livermore National Laboratory (LLNL) in the 1980s as a method to maintain a voltage directly using fusion reaction products. This has demonstrated energy capture efficiency of 48 percent.
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