9.1 Research programs

instantly producing a surrounding plasma environment for a short period of time. During the process, the density and temperature of the fuel attains a high enough

Nuclear Fusion - One Noble Goal and a Variety of Scientific and Technological Challenges

The capability of present lasers does not allow the inertial confinement technique to obtain break-even conditions, simply because the efficiency for converting electrical energy into radiation is very low, about 1–10%. Consequently, alternative approaches are being explored to achieve the ignition temperature. One such

In 1989, researchers at University of Utah (USA) and University of Southampton (UK) claimed to have achieved fusion at room temperature in a simple tabletop experiment involving the electrolysis of heavy water (deuterium oxide) using palladium electrodes [12]. According to them, when electric current passed through the water, palladium catalyzed fusion by allowing deuterium atoms to get close enough for fusion to occur. Since other experimenters failed to replicate their claim,

But in 2005, cold fusion got a major boost. Scientists at UCLA initiated fusion using a pyroelectric crystal [13]. They put the crystal into a small container filled with hydrogen, warmed the crystal to produce an electric field, and inserted a metal wire into the container to focus the charge. The focused electric field powerfully repelled the positively charged hydrogen nuclei, and in the rush away from the wire, the nuclei smashed into each other with enough force to fuse. The reaction

The aim of the controlled fusion research program is to achieve ignition, which occurs when enough fusion reactions take place for the process to become selfsustaining, with fresh fuel then being added to continue it. Once ignition is achieved, there is a net energy yield—about four times as much as with nuclear fission. As mentioned earlier, such conditions can occur when the temperature increases, causing the ions in the plasma to move faster and eventually reach speeds high enough to bring the ions close enough together. The nuclei can then fuse,

The plasma temperature needed for ignition is produced by external heating.

1. Heating by injection of neutral beams: In this method, neutralized particles with high kinetic energy, produced in an ion source, are injected into the plasma, whereby they transfer their energy to the plasma through collisions.

2. Heating by high-frequency radio or microwaves: When electromagnetic waves of appropriate frequency are beamed into the plasma, the plasma particles absorb energy from the field of the wave and transfer it to the other particles

3. Heating with current: When an electric current is passed through the plasma, it generates heat in the plasma through its resistance. As the resistance decreases with increasing temperature, this method is only suitable for initial heating.

Powerful methods were developed for this purpose. They are:

most of the scientific community no longer considers it a real phenomenon.

approach involves using beams of charged particles instead of lasers.

value to ignite the fusion reaction.

took place at room temperature.

9. Fusion research

causing a release of energy.

through collisions.

12

8. Cold fusion

Experiments with d-t fuel began in the early 1990s in the Tokamak Fusion Test Reactor in Princeton (USA) [14] and the Joint European Torus (JET) in Culham (UK) [15]. The world's first controlled release of fusion power using a 50–50 mix of tritium and deuterium with a fusion output of 16 MW from an input of 24 MW heating (Q-factor is 0.67) was achieved in 1991 by JET. The Q-factor is used to represent the ratio of the power produced in the fusion reaction to the power required to produce the fusion. It should not be confused with the Q-value of a reaction, which is the amount of energy released by that reaction. Obviously, Q-factor of 1 is breakeven. To achieve commercially viable fusion energy, the Q-factor must be much greater than one.

The 35-nation International Thermonuclear Experimental Reactor (ITER, "The Way" in Latin) project currently under construction in Cadarache, France, is the world's largest tokamak fusion reactor [16]. The goals of ITER are:


Launched in 2006, the project has been beset with technical delays, labyrinthine decision-making, and cost estimates that have soared. The reactor is now expected to be completed and become operational by 2030.

According to ITER Newsletter [16], "When completed, the plasma circulating in the core of the reactor will be 150 million degrees Celsius, or about 10 times hotter than the Sun. The massive superconducting magnets surrounding the core will be cooled to 270 degrees, as cold as the depths of space. So many of the technologies involved are really at the cutting edge."

There is a considerable amount of research into many other fusion projects at various stages of development, but ITER is the largest, with 10 times more plasma capacity than any other reactor. Although China is a participating country in the ITER project, the Chinese are nevertheless building a tokamak reactor by themselves. Known as the Experimental Advanced Superconducting Tokamak (EAST), they managed to heat hydrogen gas to a temperature of about 50 million degrees Celsius [17].

Based on the information, technologies, and experience provided by ITER, physicists and engineers at the Culham Laboratory in Oxfordshire (UK) are working to develop a Demonstration Power Station (DEMO) which, if successful in terms of systems and performance, could be used as the commercial prototype, creating a fast track to fusion power. In collaboration with the Princeton Plasma Physics Laboratory, South Korea is also developing a tokamak fusion reactor named Korean Demonstration Fusion Power Plant (K-DEMO) [18]. Both EAST and K-DEMO are due for completion by year 2030.

deliver, in a few billionths of a second, nearly 2 million Joules of energy to targets measuring a few millimeters in size. The main purpose of these projects is, however,

gain of unity. However, for making fusion energy viable in commercial power plants, the gain has to be much greater than breakeven. Since lasers are very inefficient machines, gains of at least 100 are needed for a plant to produce net power output. To that end, researchers at Lawrence Livermore National Laboratory

are exploring other approaches to developing ICF as a source for energy.

Thus far, none of the ICF facilities have achieved scientific breakeven, which is a

1. They will produce at least five times more energy than the amount of energy it will need to heat the fusing nuclei to the desired temperature. Furthermore, it is estimated that to run a 1000 MW power plant for a year, a fusion reactor will require about 3000 m<sup>3</sup> of water (source of deuterium) and 10 tonnes of lithium ore, while the current fission reactors consume 25–30 tonnes of enriched uranium. Clearly, gram for gram, fusion reactor wins the energy race

2. Fusion fuels are widely available and nearly inexhaustible. Deuterium can be distilled from all forms of water, while reserves of lithium, both terrestrial and sea-based, which would be used to produce tritium, would fulfill needs of

3. Unlike fission, fusion will have a low burden of radioactive waste. They will not produce high-level nuclear wastes like their fission counterparts, so disposal will be less of a problem. Fusions by-product is helium—an inert, nontoxic, and nonradioactive gas used to inflate childrens' balloons. Besides, there will be no fissile material that could be diverted by terrorists to build "dirty bombs." Moreover, a fusion power station would not require the

4.Fusion reactors are inherently incapable of a runaway reaction that could result in a core meltdown, the most serious calamity possible in a fission reactor. This is because there is no critical mass required for fusion. Besides, fusion reactors work like a gas burner; once the fuel supply is shut off, the reaction stops. There will, therefore, be no off-site radiation-related deaths, even from a

5. Despite being technically nonrenewable, fusion has many of the benefits of renewable energy sources, such as being a long-term source of energy

Although fusion does not generate long-lived radioactive products and the unburned gases can be treated on site, there are nevertheless few concerns related to the radioactivity induced by the high-energy neutrons (14 MeV) that are

emitting no greenhouse gases. Besides, because it is not dependent on weather, fusion could provide uninterrupted power delivery, unlike solar and wind

to support research for nuclear weapons programs.

Nuclear Fusion: Holy Grail of Energy

DOI: http://dx.doi.org/10.5772/intechopen.82335

10. Advantages/disadvantages of fusion reactors

There are many advantages of fusion reactors:

fusion reactors for millions of years.

transport of hazardous radioactive materials.

by a wide margin.

severe accident.

produced during the d-t reaction. They are:

power.

15

Under an Italian-Russian agreement, Italy's National Agency for New Technologies, Energy and Sustainable Economic Development is developing a small tokamak reactor by the name of Ignitor [19]. The reactor is based on the Alcator machine at MIT [20] which pioneered the high magnetic field approach to plasma magnetic confinement. The scientists of the project believe that unlike the larger ITER reactor, Ignitor could be ready to begin operations within a few years.

By using magnetic fields that are twice as strong as those planned for ITER, two spin-off companies, one in the USA and the other in the UK, hope to create a sustainable fusion reaction in a machine as small as 1/70th the size of ITER. They also believe, according to the August 2018 issue of Physics Today, that their reactor will be able to produce more energy than they consume. It is expected to be operational before ITER, possibly by the mid-2020s.

The Germans are working on a non-tokamak fusion reactor called Wendelstein 7-X [21]. In a test run, they produced helium plasma that lasted for one-quarter of a second and achieved a temperature of 80 million degrees Celsius. The Germans believe that their stellarator design, similar in principal to the tokamaks, will provide an inherently more stable environment for plasma and a more promising route for nuclear fusion research in general.

Another stellarator, TJ-II, designed in collaboration with Oak Ridge National Laboratory (USA), is in operation in Madrid, Spain [22]. This flagship project of the National Fusion Laboratory of Spain is a flexible, medium-size stellarator—the second largest operational stellarator in Europe, after Wendelstein 7-X.

In 2014, scientists and engineers at the American aerospace conglomerate Lockheed Martin claimed to have made a major technological breakthrough in the development of a fusion reactor [23]. They are cautiously optimistic that an operational reactor with enough energy output to power a small city, yet small enough to fit on the back of a truck, can be built before the end of this decade. However, because of the absence of further details on how their reactor works, some scientists are skeptical about the claim.

According to MIT Technology Review [24], while ongoing research centered on large tokamaks may take decades before a commercially feasible fusion reactor is built, several privately funded companies and small university-based research groups pursuing novel fusion reactor designs have delivered promising results that could shorten the timeline for producing a prototype machine from decades to several years. On the other hand, scientists of the mega-projects believe that fusion power could become a reality more quickly if the present international funding for fusion research was increased.

There have also been significant developments in research into inertial confinement fusion (ICF). Research on ICF in the USA is going on at the National Ignition Facility [25] at the Lawrence Livermore National Laboratory in California and Sandia Laboratories in New Mexico. At Sandia, an entirely different method of ICF called the Z-pinch [26], which does not use laser at all, is being investigated. Instead, it uses a strong electrical current in a plasma to generate X-rays, which compresses a tiny d-t fuel cylinder. The other notable research activity on ICF is the Laser Megajoule project in Bordeaux, France [27]. All three projects are designed to Nuclear Fusion: Holy Grail of Energy DOI: http://dx.doi.org/10.5772/intechopen.82335

Based on the information, technologies, and experience provided by ITER, physicists and engineers at the Culham Laboratory in Oxfordshire (UK) are working to develop a Demonstration Power Station (DEMO) which, if successful in terms of systems and performance, could be used as the commercial prototype, creating a fast track to fusion power. In collaboration with the Princeton Plasma Physics Laboratory, South Korea is also developing a tokamak fusion reactor named Korean Demonstration Fusion Power Plant (K-DEMO) [18]. Both EAST and

Nuclear Fusion - One Noble Goal and a Variety of Scientific and Technological Challenges

Under an Italian-Russian agreement, Italy's National Agency for New Technologies, Energy and Sustainable Economic Development is developing a small tokamak reactor by the name of Ignitor [19]. The reactor is based on the Alcator machine at MIT [20] which pioneered the high magnetic field approach to plasma magnetic confinement. The scientists of the project believe that unlike the larger ITER reac-

By using magnetic fields that are twice as strong as those planned for ITER, two

The Germans are working on a non-tokamak fusion reactor called Wendelstein 7-X [21]. In a test run, they produced helium plasma that lasted for one-quarter of a second and achieved a temperature of 80 million degrees Celsius. The Germans believe that their stellarator design, similar in principal to the tokamaks, will provide an inherently more stable environment for plasma and a more promising route

Another stellarator, TJ-II, designed in collaboration with Oak Ridge National Laboratory (USA), is in operation in Madrid, Spain [22]. This flagship project of the National Fusion Laboratory of Spain is a flexible, medium-size stellarator—the

In 2014, scientists and engineers at the American aerospace conglomerate Lockheed Martin claimed to have made a major technological breakthrough in the development of a fusion reactor [23]. They are cautiously optimistic that an operational reactor with enough energy output to power a small city, yet small enough to fit on the back of a truck, can be built before the end of this decade. However, because of the absence of further details on how their reactor works, some scientists

According to MIT Technology Review [24], while ongoing research centered on large tokamaks may take decades before a commercially feasible fusion reactor is built, several privately funded companies and small university-based research groups pursuing novel fusion reactor designs have delivered promising results that could shorten the timeline for producing a prototype machine from decades to several years. On the other hand, scientists of the mega-projects believe that fusion power could become a reality more quickly if the present international funding for

There have also been significant developments in research into inertial confinement fusion (ICF). Research on ICF in the USA is going on at the National Ignition Facility [25] at the Lawrence Livermore National Laboratory in California and Sandia Laboratories in New Mexico. At Sandia, an entirely different method of ICF called the Z-pinch [26], which does not use laser at all, is being investigated. Instead, it uses a strong electrical current in a plasma to generate X-rays, which compresses a tiny d-t fuel cylinder. The other notable research activity on ICF is the Laser Megajoule project in Bordeaux, France [27]. All three projects are designed to

second largest operational stellarator in Europe, after Wendelstein 7-X.

spin-off companies, one in the USA and the other in the UK, hope to create a sustainable fusion reaction in a machine as small as 1/70th the size of ITER. They also believe, according to the August 2018 issue of Physics Today, that their reactor

will be able to produce more energy than they consume. It is expected to be

K-DEMO are due for completion by year 2030.

operational before ITER, possibly by the mid-2020s.

for nuclear fusion research in general.

are skeptical about the claim.

fusion research was increased.

14

tor, Ignitor could be ready to begin operations within a few years.

deliver, in a few billionths of a second, nearly 2 million Joules of energy to targets measuring a few millimeters in size. The main purpose of these projects is, however, to support research for nuclear weapons programs.

Thus far, none of the ICF facilities have achieved scientific breakeven, which is a gain of unity. However, for making fusion energy viable in commercial power plants, the gain has to be much greater than breakeven. Since lasers are very inefficient machines, gains of at least 100 are needed for a plant to produce net power output. To that end, researchers at Lawrence Livermore National Laboratory are exploring other approaches to developing ICF as a source for energy.
