Nuclear Fusion: How Thrilled Should We Be?

There has been significant excitement about recent results from the Joint European Torus (JET) facility in the UK, suggesting that the dream of nuclear fusion power is inching closer to reality. We know that fusion works– it is the process that powers the Sun, offering heat and light to the Earth. For years, it has been difficult to transition from scientific laboratory experiments to sustained power production.

The central goal of fusion is to merge atomic nuclei to produce a different, heavier nucleus– dispensing energy in the process. This is unlike nuclear fission, in which a heavy nucleus such as uranium is split into smaller ones while also releasing energy.

Significant trouble has been the process of fusing light atoms, isotopes of hydrogen, or helium. As they are electrically billed, repulsing each other, they resist fusing unless nuclei are moving fast enough to get physically really near each other– demanding extreme conditions. The Sun accomplishes this at its core thanks to its enormous gravitational fields and its significant volume.

One approach utilized in laboratories on Earth is “inertial confinement,” wherein a little fusion fuel pellet about one-tenth of a centimeter in diameter is heated and compressed from the outside utilizing laser energy.

The methodology

Over the last few years, some encouraging development on this technique has been made, perhaps most especially by the National Ignition Facility in the US, where a 1.3 million Joules (a measure of energy) fusion return was reported last year. While this produced ten quadrillion Watts of power, it just lasted for a fraction (90 trillionths) of a second.

A different technique, “magnetic confinement,” has been deployed more broadly in laboratories worldwide and is believed to be among the most promising routes to materializing fusion power stations in the future.

It entails using fusion fuel held in the form of a hot plasma– a cloud of charged particles– confined by powerful magnetic fields. When creating the conditions for fusion reactions to occur, the confinement system requires keeping the fuel at an adequate temperature and density and for enough time.

Herein lies a substantial part of the challenge. The small amount of fusion fuel (usually just a few grams) requires to be heated to huge temperatures, of the order of 10 times hotter than the center of the Sun (150 million°C). Furthermore, this needs to occur while preserving confinement in a magnetic cage to sustain an energy output.

Numerous machines can be utilized to try to retain this magnetic confinement of the plasma. However, the most successful to date is the so-called “tokamak” design, which uses a torus (doughnut shape) and intricate magnetic fields to confine the plasma, as employed at the JET facility.

Small Step or Big Leap?

The recent results mark an actual stepping stone in the mission for fusion power. Overall, the 59 million Joules of energy generated over a 5 second period provided an average fusion power of around 11 million Watts.

While this is only sufficient to heat approximately 60 kettles, it is nonetheless impressive– producing an energy output 2.5 times the latest record, established back in 1997 (also at the JET facility, reaching 22 million Joules).

The success at JET is the pinnacle in years of planning and a very experienced team of committed scientists and engineers. JET is presently the biggest tokamak globally and the only device that can use both deuterium and tritium fuel (both isotopes of hydrogen).

The design of the machine, utilizing copper magnets that heat up quickly, means that it can just operate with plasma bursts of approximately a few seconds. Superconducting magnets will be needed to make the step to much longer sustained high-power operations.

The progress

Thankfully, this is the case at the ITER facility, presently being constructed in the south of France as part of an international effort including 35 countries, which is now 80% complete. For that reason, the recent outcomes have offered tremendous confidence in the engineering design and physics performance for the ITER machine design, in addition to a magnetic confinement device, which is designed to generate 500 million Watts of fusion power.

Other important difficulties remain. These consist of developing appropriately durable materials capable of withstanding the intense pressure within the machine, handling the substantial power exhaust, and, most notably, producing economically competitive energy with various other forms of energy manufacturing.

Accomplishing remarkable power outputs and sustaining them for more than a brief amount of time has been the major challenge in fusion for decades. Without this ultimately being solved, a possible fusion powerplant can not be made to work. The JET results represent a substantial landmark, albeit just marking a step along the way.

The large leap will come with scaling up of the present fusion achievements in succeeding fusion systems, such as ITER, in demonstration power plants beyond this. Furthermore, this must be possible in the near future, planning for operation by the 2050s or perhaps a little earlier.

Crucial Benefits

There is a great deal at stake. Fusion generates even more energy per gram of fuel than any other procedure that could be attained on Earth. Some of the major advantages of fusion are that the products of the process are helium and neutrons (particles that compose the atomic nucleus, together with protons)– no co2 or other greenhouse gases are released.

The raw fuels are deuterium, which can be located in seawater, and lithium, which is also abundant in large salt flats. The prospective fusion energy released from the lithium contained in one laptop battery and a bathtub of water is estimated to be equivalent to about 40 metric tons of coal.

Fusion does generate some radioactivity in the materials making up the reactor. This is not expected to be anywhere near as long-lived or extreme as the radioactive waste produced by nuclear fission– making it possibly a much safer and much more acceptable choice than traditional nuclear power.

Ultimately, Rome was not built in a day. Various other elements of human ingenuity, such as aviation, have historically taken significant amounts of time to progress to fruition. That means steps along the way that make progress are hugely important and need to be commemorated appropriately.

Fusion is creeping inexorably forward, and we are getting closer and closer to reaching that once distant dream of commercial fusion power. One day, it will give a near-infinite supply of low-carbon power for many future generations to come. While it is not there yet, it is coming.

Read the original article on Tech Xplore.

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