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A soliton explosion is an instability whereby a dissipative soliton undergoes a sudden structural collapse, but remarkably returns back to its original shape after a short transient. We recently reported the first experimental observation of this effect in a fiber laser (A. F. J. Runge et al., Optica 2, 36 (2015)). Here, we expand on our initial work, presenting a more detailed experimental and numerical study of the characteristics and dynamics of soliton explosions in passively mode-locked fiber lasers. Specifically, we explore different cavity configurations and gain levels, observing and characterizing explosion events using spectral and temporal real-time single-shot techniques. Our results highlight that the explosion characteristics observed in experiments depend critically on the position in the cavity where the output coupler is located. Furthermore, we find that the frequency at which explosions occur can be controlled by adjusting the pump power. We also identify a new kind of ``partial'' explosion, where strong spectral interference fringes appear on the pulse spectra, but a full collapse is avoided. Finally, we perform numerical simulations based on a realistic iterative cavity map, and obtain results that are in good agreement with experimental measurements. Careful analysis of the simulation results provide strong credence to the interpretation that soliton explosions can be linked to a multi-pulsing instability.

A soliton explosion is an instability whereby a dissipative soliton undergoes a sudden structural collapse, but remarkably returns back to its original shape after a short transient. We recently reported the first experimental observation of this effect in a fiber laser (A. F. J. Runge et al., Optica 2, 36 (2015)). Here, we expand on our initial work, presenting a more detailed experimental and numerical study of the characteristics and dynamics of soliton explosions in passively mode-locked fiber lasers. Specifically, we explore different cavity configurations and gain levels, observing and characterizing explosion events using spectral and temporal real-time single-shot techniques. Our results highlight that the explosion characteristics observed in experiments depend critically on the position in the cavity where the output coupler is located. Furthermore, we find that the frequency at which explosions occur can be controlled by adjusting the pump power. We also identify a new kind of ``partial'' explosion, where strong spectral interference fringes appear on the pulse spectra, but a full collapse is avoided. Finally, we perform numerical simulations based on a realistic iterative cavity map, and obtain results that are in good agreement with experimental measurements. Careful analysis of the simulation results provide strong credence to the interpretation that soliton explosions can be linked to a multi-pulsing instability.

The motivation for devoting a Theme Issue to explosions is discussed. As subsequent articles in the issue are written with the assumption that the reader has had a certain amount of previous exposure to the subject, some of the history and necessary background information are presented here. The topics on explosions that will be encountered in the remaining articles are previewed. Finally, several important future outstanding research problems, beyond those addressed in the following articles, are discussed, with the objective of complementing the coverage of explosions in this issue.

The motivation for devoting a Theme Issue to explosions is discussed. As subsequent articles in the issue are written with the assumption that the reader has had a certain amount of previous exposure to the subject, some of the history and necessary background information are presented here. The topics on explosions that will be encountered in the remaining articles are previewed. Finally, several important future outstanding research problems, beyond those addressed in the following articles, are discussed, with the objective of complementing the coverage of explosions in this issue.

The 18tb International Colloquium on the Dynamics of Explosions and Reactive Systems was held at the University of Washington from 29 July through 3 August 2001. Two hundred and twenty nine participants from 21 countries gathered to discuss the latest advances in experimental investigation and mathematical modeling of explosions and reactive systems. Two minisymposia focused on pulsed detonation engines and ram accelerators, while 186 podium presentations and 40 posters covered a broad range of theoretical and experimental topics.

The 18tb International Colloquium on the Dynamics of Explosions and Reactive Systems was held at the University of Washington from 29 July through 3 August 2001. Two hundred and twenty nine participants from 21 countries gathered to discuss the latest advances in experimental investigation and mathematical modeling of explosions and reactive systems. Two minisymposia focused on pulsed detonation engines and ram accelerators, while 186 podium presentations and 40 posters covered a broad range of theoretical and experimental topics.

The report focuses on the topic of indoor detonations in multi-chamber structures. The central part of the presented project investigated a generic model of a single-story building. By means of PETN-charges in the range of 0.5g model scales of about 1:70 were feasible. Main diagnostic were pressure measurements at the model walls and high-speed visualization of the flow field. The tests are well reproducible and easily repeated; thus a number of parametric changes was feasible (e.g., variation of the charge location, size of a venting hole in the chamber, where the detonation occurs). In addition, experiments on selected typical components of a multi-chamber structure (e.g., corridors, connecting doors, staircases) were also performed in a shock tube, in order to investigate the typical flow field phenomena in dependence from the Mach number.

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The metadata below describe the original scanning. Follow the "All Files: HTTP" link in the "View the book" box to the left to find XML files that contain more metadata about the original images and the derived formats (OCR results, PDF etc.). See also the What is the directory structure for the texts? FAQ for information about file content and naming conventions.

We study the growth of the explosion energy after shock revival in neutrino-driven explosions in two and three dimensions (2D/3D) using multi-group neutrino hydrodynamics simulations of an $11.2 M_\odot$ star. The 3D model shows a faster and steadier growth of the explosion energy and already shows signs of subsiding accretion after one second. By contrast, the growth of the explosion energy in 2D is unsteady, and accretion lasts for several seconds as confirmed by additional long-time simulations of stars of similar masses. Appreciable explosion energies can still be reached, albeit at the expense of rather high neutron star masses. In 2D, the binding energy at the gain radius is larger because the strong excitation of downward-propagating g-modes removes energy from the freshly accreted material in the downflows. Consequently, the mass outflow rate is considerably lower in 2D than in 3D. This is only partially compensated by additional heating by outward-propagating acoustic waves in 2D. Moreover, the mass outflow rate in 2D is reduced because much of the neutrino energy deposition occurs in downflows or bubbles confined by secondary shocks without driving outflows. Episodic constriction of outflows and vertical mixing of colder shocked material and hot, neutrino-heated ejecta due to Rayleigh-Taylor instability further hamper the growth of the explosion energy in 2D. Further simulations will be necessary to determine whether these effects are generic over a wider range of supernova progenitors.

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218pg.