Nuclear Fusion Flashcards
What is the potential advantage of nuclear fusion as an energy source compared to nuclear fission?
Nuclear fusion could provide a cheap, clean, and almost boundless source of energy. The end products are usually light, stable nuclei, rather than radioactive ones.
What is the major challenge in achieving nuclear fusion, and how is it related to the Coulomb barrier?
The major challenge in achieving nuclear fusion is overcoming the strong Coulomb barrier between positively charged nuclei. This barrier must be overcome to bring the nuclei close enough for fusion to occur.
What is the proton-proton chain reaction, and how does it contribute to energy generation in the Sun?
The proton-proton chain reaction is the dominant process by which hydrogen converts to helium in the Sun. It involves a series of fusion reactions starting with two protons, ultimately producing helium and releasing energy.
What are the main fusion reactions considered for controlled fusion on Earth, and why is the D-T reaction favored?
The main fusion reactions considered are deuterium-deuterium (D-D) and deuterium-tritium (D-T) reactions. The D-T reaction is favored because it releases the highest energy per reaction.
How do fusion cross-sections relate to the probability of fusion occurring, and what are they measured in?
Fusion cross-sections represent the probability of fusion occurring and are measured in barns. A larger cross-section indicates a higher probability of fusion
What is the Lawson criterion, and why is it important for achieving controlled fusion?
The Lawson criterion is an estimate of the minimum product of ion density and confinement time required for fusion to generate energy. It is important because it sets a condition for achieving controlled fusion.
What are the two main approaches to achieving fusion reactors, and how do they work?
The two main approaches are magnetic confinement fusion (e.g., Tokamak) and inertial confinement fusion (ICF). Magnetic confinement uses a uniform magnetic field to confine the plasma, while ICF uses X-ray radiation to implode a fuel pellet, achieving high densities and temperatures.
Why is it challenging to achieve fusion on Earth compared to fusion reactions that occur naturally in stars like the Sun?
Achieving fusion on Earth is challenging because it requires replicating the extreme conditions found in stars, such as high temperatures and pressures, within controlled environments.
What role does the Coulomb barrier play in nuclear fusion, and how is it related to the need for high temperatures?
The Coulomb barrier is the electrostatic repulsion between positively charged nuclei that must be overcome for fusion to occur. High temperatures are needed to provide the kinetic energy necessary to overcome this barrier.
What is the significance of the Lawson criterion in the context of fusion research?
The Lawson criterion sets a minimum requirement for the product of ion density and confinement time necessary for fusion to generate energy. Meeting this criterion is essential for achieving sustained and practical fusion reactions.
How does magnetic confinement fusion work, and what is the role of devices like the Tokamak?
Magnetic confinement fusion uses magnetic fields to confine the hot plasma within a reactor vessel. Devices like the Tokamak create a toroidal magnetic field that contains and stabilizes the plasma, enabling sustained fusion reactions.
What is inertial confinement fusion (ICF), and how does it differ from magnetic confinement fusion?
In inertial confinement fusion (ICF), high-energy lasers or particle beams are used to compress and heat a small target containing fusion fuel. Unlike magnetic confinement, ICF relies on rapid compression to achieve high densities and temperatures for fusion
What are some current challenges in achieving practical fusion energy, and what ongoing projects aim to address these challenges?
Challenges include sustaining fusion reactions at a net energy gain, controlling plasma instabilities, and developing materials that can withstand extreme conditions. Ongoing projects like ITER (International Thermonuclear Experimental Reactor) and the National Ignition Facility (NIF) aim to advance fusion research and technology.
