Nonlinear optics (NLO) is the branch of optics that describes the behaviour of light in nonlinear media, that is, media in which the polarization density P responds non-linearly to the electric field E of the light. The non-linearity is typically observed only at very high light intensities (values of atomic electric fields, typically 108 V/m) such as those provided by lasers. Above the Schwinger limit, the vacuum itself is expected to become nonlinear. In nonlinear optics, the superposition principle no longer holds.
Inertial confinement fusion (ICF) is a type of fusion energy research that attempts to initiate nuclear fusion reactions by heating and compressing a fuel target, typically in the form of a pellet that most often contains a mixture of deuterium and tritium. Typical fuel pellets are about the size of a pinhead and contain around 10 milligrams of fuel.
This timeline of nuclear fusion is an incomplete chronological summary of significant events in the study and use of nuclear fusion.
The National Ignition Facility (NIF), is a large laser-based inertial confinement fusion (ICF) research device, located at the Lawrence Livermore National Laboratory in Livermore, California. NIF uses lasers to heat and compress a small amount of hydrogen fuel with the goal of inducing nuclear fusion reactions. NIF's mission is to achieve fusion ignition with high energy gain, and to support nuclear weapon maintenance and design by studying the behavior of matter under the conditions found within nuclear weapons. NIF is the largest and most energetic ICF device built to date, and the largest laser in the world.
The Kerr effect, also called the quadratic electro-optic (QEO) effect, is a change in the refractive index of a material in response to an applied electric field. The Kerr effect is distinct from the Pockels effect in that the induced index change is directly proportional to the square of the electric field instead of varying linearly with it. All materials show a Kerr effect, but certain liquids display it more strongly than others. The Kerr effect was discovered in 1875 by John Kerr, a Scottish physicist.
Chirped pulse amplification (CPA) is a technique for amplifying an ultrashort laser pulse up to the petawatt level, with the laser pulse being stretched out temporally and spectrally, then amplified, and then compressed again. The stretching and compression uses devices that ensure that the different color components of the pulse travel different distances.
The Shiva laser was a powerful 20-beam infrared neodymium glass laser built at Lawrence Livermore National Laboratory in 1977 for the study of inertial confinement fusion (ICF) and long-scale-length laser-plasma interactions. Presumably, the device was named after the multi-armed form of the Hindu god Shiva, due to the laser's multi-beamed structure. Shiva was instrumental in demonstrating a particular problem in compressing targets with lasers, leading to a major new device being constructed to address these problems, the Nova laser.
Nova was a high-power laser built at the Lawrence Livermore National Laboratory (LLNL) in California, United States, in 1984 which conducted advanced inertial confinement fusion (ICF) experiments until its dismantling in 1999. Nova was the first ICF experiment built with the intention of reaching "ignition", a chain reaction of nuclear fusion that releases a large amount of energy. Although Nova failed in this goal, the data it generated clearly defined the problem as being mostly a result of Rayleigh–Taylor instability, leading to the design of the National Ignition Facility, Nova's successor. Nova also generated considerable amounts of data on high-density matter physics, regardless of the lack of ignition, which is useful both in fusion power and nuclear weapons research.
In nonlinear optics, filament propagation is propagation of a beam of light through a medium without diffraction. This is possible because the Kerr effect causes an index of refraction change in the medium, resulting in self-focusing of the beam.
Argus was a two-beam high power infrared neodymium doped silica glass laser with a 20 cm (7.9 in) output aperture built at Lawrence Livermore National Laboratory in 1976 for the study of inertial confinement fusion. Argus advanced the study of laser-target interaction and paved the way for the construction of its successor, the 20 beam Shiva laser.
The Janus laser was a two beam infrared neodymium doped silica glass laser built at Lawrence Livermore National Laboratory in 1974 for the study of inertial confinement fusion. Janus was built using about 100 pounds of Nd:glass laser material. Initially, Janus was only capable of producing laser pulses of about 10 joules of energy at a power of 0.5TW. It was the first laser at Livermore to generate thermonuclear fusion via the irradiation of DT gas filled glass targets.
Novette was a two beam neodymium glass testbed laser built at Lawrence Livermore National Laboratory in about 15 months throughout 1981 and 1982 and was completed in January 1983. Novette was made using recycled parts from the dismantled Shiva and Argus lasers and borrowed parts from the future Nova laser. Its main intended purpose was to validate the proposed design and expected performance of the then planned Nova laser. In addition to being used for the further study of enhanced laser to target plasma energy coupling utilizing frequency tripled light and examining its benefits with respect to inertial confinement fusion, Novette was also used in the world's first laboratory demonstration of an x-ray laser in 1984.
The Long Path laser was an early high energy infrared laser at the Lawrence Livermore National Laboratory used to study inertial confinement fusion. Long path was completed in 1972 and was the first ICF laser ever to use neodymium doped glass as the lasing medium. It was capable of delivering about 50 joules of light at 1,062 nm onto a target in ~10 ns pulses. It did not use spatial filters to smooth the beam after amplification stages and thus had a fairly poor beam quality. Long path was mostly used to investigate laser energy absorption in deuterated plastic targets.
The High Power laser Energy Research facility (HiPER), is a proposed experimental laser-driven inertial confinement fusion (ICF) device undergoing preliminary design for possible construction in the European Union. As of 2019, the effort appears to be inactive.
Self-focusing is a non-linear optical process induced by the change in refractive index of materials exposed to intense electromagnetic radiation. A medium whose refractive index increases with the electric field intensity acts as a focusing lens for an electromagnetic wave characterized by an initial transverse intensity gradient, as in a laser beam. The peak intensity of the self-focused region keeps increasing as the wave travels through the medium, until defocusing effects or medium damage interrupt this process. Self-focusing of light was discovered by Gurgen Askaryan.
A laser beam profiler captures, displays, and records the spatial intensity profile of a laser beam at a particular plane transverse to the beam propagation path. Since there are many types of lasers — ultraviolet, visible, infrared, continuous wave, pulsed, high-power, low-power — there is an assortment of instrumentation for measuring laser beam profiles. No single laser beam profiler can handle every power level, pulse duration, repetition rate, wavelength, and beam size.
KMS Fusion was the only private sector company to pursue controlled thermonuclear fusion research using laser technology. Despite limited resources and numerous business problems KMS successfully demonstrated fusion from the Inertial Confinement Fusion (ICF) process. They achieved compression of a deuterium-tritium pellet from laser-energy in December 1973, and on May 1, 1974 carried out the world’s first successful laser-induced fusion. Neutron-sensitive nuclear emulsion detectors, developed by Nobel Prize winner Robert Hofstadter, were used to provide evidence of this discovery.
LIFE, short for Laser Inertial Fusion Energy, was a fusion energy effort run at Lawrence Livermore National Laboratory between 2008 and 2013. LIFE aimed to develop the technologies necessary to convert the laser-driven inertial confinement fusion concept being developed in the National Ignition Facility (NIF) into a practical commercial power plant, a concept known generally as inertial fusion energy (IFE). LIFE used the same basic concepts as NIF, but aimed to lower costs using mass-produced fuel elements, simplified maintenance, and diode lasers with higher electrical efficiency.
John D. Lindl is an American physicist who specializes in inertial confinement fusion (ICF). He is currently the Chief Scientist of the National Ignition Facility at the Lawrence Livermore National Laboratory.
