Regular articles|3 Article(s)
Heat wave fast ignition in inertial confinement energy
Shalom Eliezer, and Shirly Vinikman Pinhasi
An accelerated micro-foil is used to ignite a pre-compressed cylindrical shell containing deuterium–tritium fuel. The well-known shock wave ignition criterion and a novel criterion based on heat wave ignition are developed in this work. It is shown that for heat ignition very high impact velocities are required. It is suggested that a multi-petawatt laser can accelerate a micro-foil to relativistic velocities in a very short time duration (?picosecond) of the laser pulse. The cylindrical geometry suggested here for the fast ignition approach has the advantage of geometrically separating the nanosecond lasers that compress the target from the picosecond laser that accelerates the foil. The present model suggests that nuclear fusion by micro-foil impact ignition could be attained with currently existing technology.
High Power Laser Science and Engineering
  • Publication Date: Jan. 01, 1900
  • Vol.1 Issue, 1 01000044 (2013)
The proposal and realization on more exact modeling of COIL performance
Shouxian Li, Xiaojian Shu, Yanyi Du, Hua Su, Yan Li, and Zhen Yu
The chemical oxygen–iodine laser (COIL) is the shortest-wavelength high-power chemical laser that has been demonstrated. The characteristics, such as good atmospheric propagation, short wavelength and excellent transmission through optical fibers, make the COIL a good candidate for high-power laser application. To model the complete COIL lasing interaction, a three-dimensional formulation of the fluid dynamics, species continuity and radiation transport equations is necessary. The computational effort to calculate the flow field over the entire nozzle bank with a grid fine enough to resolve the injection holes is so large as to preclude doing the calculation. The approach to modeling chemical lasers then has been to reduce the complexity of the model to correspond to the available computational capability, adding details as computing power increased. The modeling of lasing in the COIL medium is proposed, which is coupling with the effects induced by transverse injection of secondary gases, non-equilibrium chemical reactions, nozzle tail flow and boundary layer. The coupled steady solutions of the fluid dynamics and optics in a COIL complex three-dimensional cavity flow field are obtained following the proposal. The modeling results show that these effects have some influence on the lasing properties. A feasible methodology and a theoretical tool are offered to predict the beam quality for large-scale COIL devices.
High Power Laser Science and Engineering
  • Publication Date: Jan. 01, 1900
  • Vol.1 Issue, 1 01000050 (2013)
stripe lasers for high-power fiber coupled pump modules
René Platz, Götz Erbert, Wolfgang Pittroff, Moritz Malchus, Klaus Vogel, and Günther Tränkle
We present a 940 nm quasi-continuous wave semiconductor laser designed as a building block for high-power fiber coupled pump modules. The laser comprises a $400~\mathrm{\mu} \mathrm{m} $ narrow-stripe array mounted on an aluminum nitride substrate using hard solder. The chip has been optimized for high optical power and low lateral far-field angles. Two vertical and six lateral structure variations have been investigated to determine the best achievable performance. Operating at 1 ms pulse width and a repetition rate of 10 Hz, the laser device reaches a maximum pulse power of 86 W from a $400~\mathrm{\mu} \mathrm{m} $ aperture and more than 62% maximum conversion efficiency. Low lateral far-field angles (95% power enclosed) of 11.5° and 13.5°, depending on the epitaxial design, enable efficient multimode fiber coupling. The potential for highly reliable applications has been demonstrated.
High Power Laser Science and Engineering
  • Publication Date: Jan. 01, 1900
  • Vol.1 Issue, 1 01000060 (2013)