Appendix G: Glossary of Terms and Acronyms Used in This Report

Terms

Cryogenic: involving very low temperatures

Diode-pumped lasers: lasers wherein laser diodes illuminate a solid gain medium (such as a crystal or glass).

Direct drive: inertial confinement fusion (ICF) technique whereby the driver energy strikes the fuel capsule directly.

Driver: The mechanism by which energy is delivered to the fuel capsule. Typical techniques use lasers, heavy-ion beams, and Z-pinches.

Fast ignition: ICF technique whereby the driver gradually compresses the fuel capsule, at which point a high-intensity, ultrashort-pulse laser strikes the fuel to trigger ignition.

Gain: ratio of the fusion energy released by the target to the driver energy applied to the target in a single explosion.

Heavy-ion fusion: ICF technique whereby ions of heavy elements are accelerated and directed onto a target.

High average power: maintaining a high, repeatable driver power that is suitable for an inertial confinement fusion-based power plant.

High-energy-density science: the study of the creation, behavior, and interaction of matter with extremely high energy densities.

High repetition rate: maintaining a high rate for engaging the driver or igniting the target, suitable for an inertial confinement fusion-based power plant (e.g., 10 Hz).

Ignition (broad definition): the condition in a plasma when self-heating from nuclear fusion reactions is at a sufficient rate to maintain the plasma, its temperature and fusion reactions, without the need to apply any external energy to the plasma.

Ignition (IFE): a state when fusion gain exceeds unity, i.e., when the fusion energy released in a single explosion exceeds the energy applied to the target.



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Appendix G: Glossary of Terms and Acronyms Used in This Report Terms Cryogenic: involving very low temperatures Diode-pumped lasers: lasers wherein laser diodes illuminate a solid gain medium (such as a crystal or glass). Direct drive: inertial confinement fusion (ICF) technique whereby the driver energy strikes the fuel capsule directly. Driver: The mechanism by which energy is delivered to the fuel capsule. Typical techniques use lasers, heavy-ion beams, and Z-pinches. Fast ignition: ICF technique whereby the driver gradually compresses the fuel capsule, at which point a high-intensity, ultrashort-pulse laser strikes the fuel to trigger ignition. Gain: ratio of the fusion energy released by the target to the driver energy applied to the target in a single explosion. Heavy-ion fusion: ICF technique whereby ions of heavy elements are accelerated and directed onto a target. High average power: maintaining a high, repeatable driver power that is suitable for an inertial confinement fusion-based power plant. High-energy-density science: the study of the creation, behavior, and interaction of matter with extremely high energy densities. High repetition rate: maintaining a high rate for engaging the driver or igniting the target, suitable for an inertial confinement fusion-based power plant (e.g., 10 Hz). Ignition (broad definition): the condition in a plasma when self-heating from nuclear fusion reactions is at a sufficient rate to maintain the plasma, its temperature and fusion reactions, without the need to apply any external energy to the plasma. Ignition (IFE): a state when fusion gain exceeds unity, i.e., when the fusion energy released in a single explosion exceeds the energy applied to the target. 45

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Indirect drive: inertial confinement fusion technique whereby the driver energy strikes the fuel capsule indirectly, i.e., by the x-rays produced by heating a high-Z enclosure (hohlraum) that surrounds the fuel capsule. Inertial confinement fusion (ICF): concept in which a driver delivers energy to the outer surface of a pellet of fuel (typically containing a mixture of deuterium and tritium), heating and compressing it. The heating and compression then initiate a fusion chain reaction. Inertial fusion energy: concept whereby ICF is used to predictably and continuously initiate fusion chain reactions that yield more energy than that incident on the fuel from the driver for the ultimate purpose of producing electrical power. Krypton fluoride (KrF) laser: a gas laser that operates in the ultraviolet at 248nm. Magnetic target fusion: ICF technique whereby a magnetic field is created surrounding the target, and the magnetic field is then imploded around the target, initiating fusion reactions. Pulse compression: a technique whereby the incident pulse is compressed to deliver the energy in a shorter time. Pulsed-power fusion: ICF technique whereby a large electrical current is used to magnetically implode a target. Reactor chamber: The apparatus in which the fusion reactions would take place in an inertial fusion energy power plant, and which would contain and capture the resulting energy released from repeated ignition. Shock ignition: ICF technique that uses hydrodynamic shocks to ignite the compressed hot spot. Target: the fuel capsule, together with a holhraum or other energy-focusing device (if one is used), that is struck by the driver’s incident energy in order to initiate fusion reactions. Acronyms DOE U.S. Department of Energy GWe Gigawatts of electrical power ICF Inertial confinement fusion 46

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IFE Inertial fusion energy LIFE Laser Inertial Fusion Energy MeV Million electron volts MFE Magnetic fusion energy NIF National Ignition Facility NNSA National Nuclear Security Administration NRC National Research Council OFES Office of Fusion Energy Sciences (DOE) R&D Research and development 47