Glossary

powers the stars and holds promise as a clean energy source on Earth. It combines light atomic nuclei to form heavier ones, releasing enormous energy. The process faces challenges but offers potential benefits like abundant fuel and minimal waste.

Controlled fusion research focuses on overcoming obstacles to harness this power. Scientists explore magnetic and methods, aiming to meet strict criteria for sustainable reactions. plays a crucial role in enabling fusion at lower temperatures than classically expected.

Nuclear Fusion

Principles of nuclear fusion

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  • Nuclear fusion combines light atomic nuclei (hydrogen isotopes and ) to form heavier nuclei
  • Fusion releases large amounts of energy due to the conversion of mass to energy according to Einstein's equation E=mc2E=mc^2
  • Fusion reactions power the Sun and other stars by gravitational compression and high temperatures enabling fusion in stellar cores
  • Fusion has potential as a nearly limitless, clean energy source on Earth with abundant fuel sources
    • Deuterium extracted from seawater
    • Tritium bred from lithium
  • Fusion produces no greenhouse gas emissions or long-lived radioactive waste
  • Fusion has higher energy density compared to fossil fuels and fission reactors
  • The energy released in fusion reactions is related to the of the nuclei involved

Controlled fusion for energy production

  • Challenges in achieving controlled fusion include overcoming electrostatic repulsion between positively charged nuclei, confining and stabilizing hot plasma, and achieving high enough temperature, density, and confinement time simultaneously ()
  • (MCF) uses strong magnetic fields to confine plasma in a toroidal shape
    • Tokamaks
    • Stellarators
  • (ICF) uses high-powered lasers or ion beams to compress and heat a small fuel pellet, relying on the inertia of the fuel to maintain confinement during the reaction
  • Other methods being researched include , , and reactions ()
  • The probability of fusion occurring is described by the , which varies with particle energy and type of reaction

Quantum tunneling in fusion reactions

  • Quantum tunneling is a quantum mechanical phenomenon where particles can pass through potential barriers that they classically could not surmount
  • In stellar fusion, quantum tunneling allows hydrogen nuclei to overcome their electrostatic repulsion and fuse at lower temperatures than classically predicted, enabling stars to sustain fusion reactions at their core temperatures (around 15 million K for the Sun)
  • In practical applications, muon-catalyzed fusion relies on quantum tunneling enhanced by the presence of muons (heavy electrons)
    • Muons shield the positive charge of nuclei, allowing them to tunnel and fuse more easily
  • concept uses electron confinement to create a virtual cathode, which can enhance quantum tunneling rates
  • Understanding and harnessing quantum tunneling could lead to more efficient fusion reactor designs and lower the temperature and confinement requirements for practical fusion power

Fusion reactor considerations

  • Fusion reactions in a controlled environment are often referred to as thermonuclear reactions due to the high temperatures required
  • Achieving , where the fusion reaction becomes self-sustaining, is a crucial milestone in fusion research
  • of reactor materials is an important consideration in fusion reactor design and safety

Key Terms to Review (31)

Aneutronic Fusion: Aneutronic fusion is a type of nuclear fusion reaction that produces energy without the emission of free neutrons. Unlike traditional fusion reactions, aneutronic fusion aims to generate power through the fusion of light nuclei, resulting in the release of charged particles rather than neutrons.
Binding energy: Binding energy is the energy required to disassemble a nucleus into its component protons and neutrons. It is a measure of the stability of a nucleus and is equivalent to the mass defect of the nucleus.
Binding Energy: Binding energy is the amount of energy required to separate a nucleus into its individual protons and neutrons. It represents the strong nuclear force that holds the nucleus together, and it is a crucial concept in understanding nuclear stability, radioactive decay, and nuclear reactions such as fusion and fission.
Break-even: The break-even point in nuclear fusion is the condition where the energy produced by the fusion reactions equals the energy input required to sustain those reactions. Achieving break-even is a significant milestone towards practical and sustainable fusion energy.
D-T Fusion: D-T fusion, also known as deuterium-tritium fusion, is a nuclear fusion reaction in which a deuterium (D) nucleus and a tritium (T) nucleus fuse to form a helium nucleus and a high-energy neutron. This type of fusion reaction is one of the most promising approaches for generating controlled nuclear fusion power, as it requires relatively low temperatures compared to other fusion reactions.
Deuterium: Deuterium, also known as heavy hydrogen, is a stable isotope of hydrogen with one proton and one neutron in the nucleus, as opposed to the more common hydrogen isotope with just one proton. This unique composition gives deuterium distinct properties that are relevant in the contexts of nuclear fusion and nuclear weapons.
Electron volt: An electron volt (eV) is a unit of energy equal to the amount of kinetic energy gained or lost by an electron when it moves through an electric potential difference of one volt. It is commonly used in atomic and particle physics.
Electron Volt: The electron volt (eV) is a unit of energy used in atomic and nuclear physics to measure the energy gained by a single electron when it is accelerated through a potential difference of one volt. It is a fundamental unit that connects the concepts of electric potential, energy, and the behavior of charged particles in various physics contexts.
Fusion Cross Section: The fusion cross section is a measure of the probability of fusion occurring between two nuclei. It represents the effective area of interaction between the nuclei and is a crucial parameter in understanding and predicting the rate of nuclear fusion reactions, which are the fundamental processes powering the Sun and other stars.
Helium Ash: Helium ash refers to the byproduct of nuclear fusion reactions, specifically the fusion of hydrogen isotopes to form helium. This process, known as the proton-proton chain, is the primary energy-generating mechanism in the core of stars, including our Sun.
Ignition: Ignition is the process of initiating a chemical reaction, such as combustion, by providing the necessary energy to start the reaction. It is a critical concept in the context of fusion, where the ignition of a fusion reaction is a crucial step in the energy-generating process.
Inertial confinement: Inertial confinement is a technique used to achieve nuclear fusion by using high-energy lasers or ion beams to compress and heat a small fuel pellet. The rapid compression creates the high temperatures and pressures necessary for fusion reactions to occur.
Inertial Confinement Fusion: Inertial confinement fusion (ICF) is a type of nuclear fusion process where energy is generated by compressing and heating a fuel target, typically a small pellet containing a mixture of deuterium and tritium, to the point where nuclear fusion reactions occur. The confinement of the fuel is achieved through the inertia of the imploding material rather than by magnetic fields as in magnetic confinement fusion.
KeV: keV, or kiloelectron volt, is a unit of energy commonly used in the context of atomic and nuclear physics. It represents the amount of energy gained by an electron when it is accelerated through a potential difference of one thousand volts. This unit is particularly relevant in the understanding of X-rays and fusion processes.
Lawson Criterion: The Lawson criterion is a set of conditions that must be met for a nuclear fusion reaction to be self-sustaining and produce a net energy output. It is a fundamental concept in the field of fusion energy research and development.
Magnetic confinement: Magnetic confinement is a method used to contain hot plasma within a magnetic field to sustain nuclear fusion reactions. It prevents the plasma from coming into contact with the reactor walls, which could cool and contaminate it.
Magnetic Confinement Fusion: Magnetic confinement fusion is a process of generating energy by fusing light atomic nuclei, such as hydrogen, in a controlled environment using powerful magnetic fields to confine and heat the plasma. This method aims to harness the immense energy released during the fusion process to potentially provide a sustainable and clean source of energy.
Magnetized Target Fusion: Magnetized target fusion (MTF) is a type of fusion energy technology that combines aspects of magnetic confinement fusion and inertial confinement fusion. It aims to achieve nuclear fusion by using a magnetically confined plasma that is then rapidly compressed to achieve the high temperatures and densities required for fusion to occur.
Muon-Catalyzed Fusion: Muon-catalyzed fusion is a nuclear fusion process in which a muon, a subatomic particle similar to an electron but with a much greater mass, is used to catalyze the fusion of hydrogen isotopes, such as deuterium and tritium, at much lower temperatures than normally required for thermonuclear fusion. This process allows for the possibility of achieving fusion reactions more efficiently than traditional methods.
Neutron Activation: Neutron activation is the process by which a stable nucleus is transformed into a radioactive nucleus by the absorption of a neutron. This process is particularly important in the context of nuclear fusion, where the fusion of light nuclei can lead to the production of neutrons that can then activate other nuclei.
Neutron Emission: Neutron emission is the process in which a nucleus spontaneously ejects a neutron, resulting in the transformation of the parent nucleus into a daughter nucleus with one less neutron. This phenomenon is a common occurrence in various nuclear processes, including fusion reactions.
Nuclear Fusion: Nuclear fusion is the process in which two or more atomic nuclei collide at high speeds and join together to form a new, heavier nucleus. This release of energy is the fundamental source of power for stars and can be harnessed for practical applications on Earth.
Plasma Confinement: Plasma confinement refers to the process of containing and controlling a high-temperature plasma, which is a state of matter composed of ionized gases, in order to harness its potential for fusion energy production. This is a critical aspect of nuclear fusion research and technology development.
Polywell Fusion: Polywell fusion is a type of fusion reactor design that utilizes a magnetic field to confine a plasma and facilitate the fusion of light atomic nuclei, generating energy in the process. It is a novel approach to achieving controlled nuclear fusion as a potential source of clean, sustainable energy.
Proton-Boron Fusion: Proton-boron fusion, also known as the proton-boron cycle or the p-B11 fusion, is a nuclear fusion reaction that occurs between a proton and the boron-11 isotope. This fusion process is of interest in the field of nuclear energy and fusion power generation due to its potential advantages over other fusion reactions.
Proton-Proton Chain: The proton-proton chain, also known as the proton-proton fusion process, is the primary mechanism by which energy is generated in the core of main-sequence stars like our Sun. It is a series of nuclear fusion reactions that convert hydrogen into helium, releasing a significant amount of energy in the process.
Quantum Tunneling: Quantum tunneling is a quantum mechanical phenomenon where a particle, such as an electron, can penetrate and traverse through a potential energy barrier, even though the particle does not have enough classical energy to overcome the barrier. This process is a fundamental concept in quantum physics and has important implications in various fields, including nuclear fusion.
Stellarator: A stellarator is a type of magnetic confinement fusion reactor that uses a complex, twisted magnetic field to confine a hot plasma, enabling nuclear fusion reactions to occur. It is one of the main approaches to achieving controlled thermonuclear fusion power.
Thermonuclear Reaction: A thermonuclear reaction, also known as a fusion reaction, is a nuclear reaction in which two light atomic nuclei combine to form a heavier nucleus, releasing a large amount of energy in the process. This type of reaction is the fundamental process powering the Sun and other stars, as well as being the basis for the development of thermonuclear weapons and fusion power.
Tokamak: A tokamak is a device used to confine a plasma in the shape of a torus for the purpose of generating energy through nuclear fusion. It is one of the most widely studied magnetic confinement devices and is considered a leading candidate for the realization of fusion power.
Tritium: Tritium is a radioactive isotope of hydrogen with two neutrons and one proton in its nucleus. It is a key component in the fusion process and plays a crucial role in the development of nuclear weapons.
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