Bright Coherent Ultrahigh Harmonics in the keV X-ray Regime from Mid-Infrared Femtosecond Lasers

High-harmonic generation (HHG) traditionally combines ~100 near-infrared laser photons to generate bright, phase-matched, extreme ultraviolet beams when the emission from many atoms adds constructively. Here, we show that by guiding a mid-infrared femtosecond laser in a high-pressure gas, ultrahigh harmonics can be generated, up to orders greater than 5000, that emerge as a bright supercontinuum that spans the entire electromagnetic spectrum from the ultraviolet to more than 1.6 kilo–electron volts, allowing, in principle, the generation of pulses as short as 2.5 attoseconds. The multiatmosphere gas pressures required for bright, phase-matched emission also support laser beam self-confinement, further enhancing the x-ray yield. Finally, the x-ray beam exhibits high spatial coherence, even though at high gas density the recolliding electrons responsible for HHG encounter other atoms during the emission process.The experimental work was funded by a National Security Science and Engineering Faculty Fellowship, and the NSF Center for EUV Science and Technology. A.G., A.J.-B., M.M.M., H.C.K. and A. Becker acknowledge support for theory from the U.S. Air Force Office of Scientific Research (grant no. FA9550-10-1-0561); A. Baltuška acknowledges support from Austrian Science Fund (FWF, grant no. U33-16) and the Austrian Research Promotion Agency (FFG, Project 820831 UPLIT); and C.H.-G. and L.P. acknowledge support from Junta de Castilla y León, Spanish MINECO (CSD2007-00013 and FIS2009-09522), and from Centro de Láseres Pulsados, CLPU. T.P., M.-C.C., A. Bahabad, M.M.M. and H.C.K. have filed for a patent on “Method for phase-matched generation of coherent soft and hard X-rays using IR lasers,” U.S. patent application 61171783 (2008)

Lawson criterion for ignition exceeded in an inertial fusion experiment

For more than half a century, researchers around the world have been engaged in attempts to achieve fusion ignition as a proof of principle of various fusion concepts. Following the Lawson criterion, an ignited plasma is one where the fusion heating power is high enough to overcome all the physical processes that cool the fusion plasma, creating a positive thermodynamic feedback loop with rapidly increasing temperature. In inertially confined fusion, ignition is a state where the fusion plasma can begin "burn propagation" into surrounding cold fuel, enabling the possibility of high energy gain. While "scientific breakeven" (i.e., unity target gain) has not yet been achieved (here target gain is 0.72, 1.37 MJ of fusion for 1.92 MJ of laser energy), this Letter reports the first controlled fusion experiment, using laser indirect drive, on the National Ignition Facility to produce capsule gain (here 5.8) and reach ignition by nine different formulations of the Lawson criterion

[Medical education in the field of psychosomatic medicine and psychotherapy at the German universities in 2006]

BACKGROUND: The new licensing regulations for physicians introduced in 2002 place core competencies in the field of Psychosomatic Medicine and Psychotherapy at the centre of medical training and have been considered to constitute a favourable opportunity for psychosocial faculties. To date, no data have been published concerning the consequences of these new regulations. METHODS: All 34 chairs of Psychosomatic Medicine and Psychotherapy currently held by professors were surveyed by means of a written questionnaire at the beginning of the year 2006, regarding the present teaching situation and changes occurring through the introduction of the new regulations, as well as particular problem areas and respective solutions and suggestions. RESULTS: The rate of return for the questionnaires was 100 %. The consequences of the new regulations were rated predominantly positively. From a content point of view, classes continue to be more heavily weighted in cognitive areas and less so in areas of clinical practice; demands for an emphasis on affective learning objectives hence appear to have not been adequately met thus far. The newly established course formats (cross-sectional areas, obligatory optional courses, tutorials) also appear to have been employed to a rather limited degree. In addition to a lack of resources, the co-ordination with other specialist areas as well as the adequate assessment of teaching content poses a particular problem. DISCUSSION: The field of Psychosomatic Medicine and Psychotherapy constitutes an important engine for the didactic and content-related advancement of the medical curriculum in Germany. Nevertheless, the opportunities which the new licensing regulations for physicians offer to psychosocial faculties have not yet been entirely made use of. Surveyed individuals consider nationwide agreement concerning learning objectives, an exchange of experiences regarding the efficient and creative use of available resources and the development of suitable assessment methodologies, to be tasks to be urgently undertaken