Global hybrid (electron fluid, kinetic ions) and fully kinetic simulations of the magnetosphere have been used to show surprising interconnection between shocks, turbulence, and magnetic reconnection. In particular, collisionless shocks with their reflected ions that can get upstream before retransmission can generate previously unforeseen phenomena in the post shocked flows: (i) formation of reconnecting current sheets and magnetic islands with sizes up to tens of ion inertial length. (ii) Generation of large scale low frequency electromagnetic waves that are compressed and amplified as they cross the shock. These "wavefronts" maintain their integrity for tens of ion cyclotron times but eventually disrupt and dissipate their energy. (iii) Rippling of the shock front, which can in turn lead to formation of fast collimated jets extending to hundreds of ion inertial lengths downstream of the shock. The jets, which have high dynamical pressure, "stir" the downstream region, creating large scale disturbances such as vortices, sunward flows, and can trigger flux ropes along the magnetopause. This phenomenology closes the loop between shocks, turbulence, and magnetic reconnection in ways previously unrealized. These interconnections appear generic for the collisionless plasmas typical of space and are expected even at planar shocks, although they will also occur at curved shocks as occur at planets or around ejecta. V C 2014 AIP Publishing LLC. [http://dx.

We present the results of an experiment where amorphous carbon undergoes a phase transition induced by femtosecond 830 eV x-ray free-electron laser pulses. The phase transition threshold fluence is found to be 282 ± 11 mJ/cm 2 . Atomic force microscopy, photoelectron microscopy, and micro-Raman spectroscopy give experimental evidence for the phase transition in terms of a volume expansion, graphitization, and change of local order of the irradiated sample area. The interaction is modeled by an accurate time-dependent treatment of the ionization dynamics coupled to a two-temperature model. At the phase transition fluence threshold the free-electron density N e is found to be at maximum 9 × 10 20 cm −3 while the ion (atom) temperature is found to be 1050 K, e.g., above the crystallization activation temperature reported in the literature. This low ionization rate and high atom temperature suggest a thermally activated phase transition.

No abstract

Los Alamos National Laboratory, an affirmative actionkqual opportunity employer, is operated by the University of California for the U.S. Department of Energy under contract W-7405ENG-36. By acceptance of this article, the publisher recognizes that the U.S. Wemrnent retains a nonexclusive, royalty-free license to publish or reproduce the published form of this contribution, or to allow others to do so, for U.S. Government purposes. Los Alamos National Laboratory requests that the publisher identify this article as work performed under the auspices of the U.S. Department of Energy. The Los Alamos National laboratory strongly supports academic freedom and a researcher's right to publish; as an institution, however, the Laboratory does not endorse the viewpoint of a publication or guarantee its technical correctness. Form 836 (10196)Portions of this document m y be illegible in electronic image products. b a g s are pnrduced from the best mailable original docum- DISCLAIMERThis report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, make any warranty, express or implied, or assumes any legal liability or mpoirsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or senice by trade name, trademark, manufacturer, or otherwise does not necessan'ly constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof. FOAM-BUFFERED LASER-MATTER INTERACTIONS

No abstract

No abstract

No abstract

Plasma flow to an obstacle is examined using the two-fluid equations. In this model the obstacle is assumed to be a two-dimensional strip that extends to infinity in they direction (slab g~ometry?. An obstacle inserted into a magnetized plasma will cast a "shadow" along the m~gnetlc field hn~s. The natural collection length of such an obstacle is a measure of the length of Its sh_adow. This study shows that in a typical fusion tokamak, where c,!Oc;d< 1 (fie;• cs are the Ion cyclotron frequency and the ion acoustic speed, respectively, dis the half-width of the ~trip), the particle collec_tion length of an obstacle can be approximated as L 11 = 0.23c 5