High-order harmonic generation with a strong laser field and an attosecond-pulse train: the Dirac Delta comb and monochromatic limits

In recent publications, it has been shown that high-order harmonic generation can be manipulated by employing a time-delayed attosecond pulse train superposed to a strong, near-infrared laser field. It is an open question, however, which is the most adequate way to approximate the attosecond pulse train in a semi-analytic framework. Employing the Strong-Field Approximation and saddle-point methods, we make a detailed assessment of the spectra obtained by modeling the attosecond pulse train by either a monochromatic wave or a Dirac-Delta comb. These are the two extreme limits of a real train, which is composed by a finite set of harmonics. Specifically, in the monochromatic limit, we find the downhill and uphill sets of orbits reported in the literature, and analyze their influence on the high-harmonic spectra. We show that, in principle, the downhill trajectories lead to stronger harmonics, and pronounced enhancements in the low-plateau region. These features are analyzed in terms of quantum interference effects between pairs of quantum orbits, and compared to those obtained in the Dirac-Delta limit.Comment: 10 pages, 7 figures (eps files). To appear in Laser Physic

Beamlet scraping and its influence on the beam divergence at the BATMAN Upgrade test facility

For the ITER fusion experiment, two neutral beam injectors are required for plasma heating and current drive. Each injector supplies a power of about 17 MW, obtained from neutralization of 40 A (46 A), 1 MeV (0.87 MeV) negative deuterium (hydrogen) ions. The full beam is composed of 1280 beamlets, formed in 16 beamlet groups, and strict requirements apply to the beamlet core divergence (<7 mrad). The test facility BATMAN Upgrade uses an ITER-like grid with one beamlet group, which consists of 70 apertures. In a joint campaign performed by IPP and Consorzio RFX to better assess the beam optics, the divergence of a single beamlet was compared to a group of beamlets at BATMAN Upgrade. The single beamlet is measured with a carbon fiber composite tile calorimeter and by beam emission spectroscopy, whereas the divergence of the group of beamlets is measured by beam emission spectroscopy only. When increasing the RF power at low extraction voltages, the divergence of the beamlet and of the group of beamlets is continuously decreasing and no inflection point toward an overperveant beam is found. At the same time, scraping of the extracted ion beam at the second grid (extraction grid) takes place at higher RF power, supported by the absence of the normally seen linear behavior between the measured negative ion density in the plasma close to the extraction system and the measured extracted ion current. Beside its influence on the divergence, beamlet scraping needs to be considered for the determination of the correct perveance and contributes to the measured coextracted electron current

Electron propagation in crossed magnetic and electric fields

Laser-atom interaction can be an efficient mechanism for the production of coherent electrons. We analyze the dynamics of monoenergetic electrons in the presence of uniform, perpendicular magnetic and electric fields. The Green function technique is used to derive analytic results for the field--induced quantum mechanical drift motion of i) single electrons and ii) a dilute Fermi gas of electrons. The method yields the drift current and, at the same time it allows us to quantitatively establish the broadening of the (magnetic) Landau levels due to the electric field: Level number k is split into k+1 sublevels that render the $k$th oscillator eigenstate in energy space. Adjacent Landau levels will overlap if the electric field exceeds a critical strength. Our observations are relevant for quantum Hall configurations whenever electric field effects should be taken into account.Comment: 11 pages, 2 figures, submitte

Vitamin C content in Habanero pepper accessions (Capsicum chinense)

O objetivo deste trabalho foi quantificar o teor devitamina C em 22 acessos de C. chinense do grupo varietal 'Habanero", procedentes do programa de melhoramento genético da Embrapa Hortaliças

Metal-Specific Reactivity in Single-Atom Catalysts: CO Oxidation on 4d and 5d Transition Metals Atomically Dispersed on MgO

[EN] Understanding and tuning the catalytic properties of metals atomically dispersed on oxides are major stepping-stones toward a rational development of single-atom catalysts (SACs). Beyond individual showcase studies, the design and synthesis of structurally regular series of SACs opens the door to systematic experimental investigations of performance as a function of metal identity. Herein, a series of single-atom catalysts based on various 4d (Ru, Rh, Pd) and Sd (Ir, Pt) transition metals has been synthesized on a common MgO carrier. Complementary experimental (X-ray absorption spectroscopy) and theoretical (Density Functional Theory) studies reveal that, regardless of the metal identity, metal cations occupy preferably octahedral coordination MgO lattice positions under step-edges, hence highly confined by the oxide support. Upon exposure to O-2-lean CO oxidation conditions, FTIR spectroscopy indicates the partial deconfinement of the monatomic metal centers driven by CO at precatalysis temperatures, followed by the development of surface carbonate species under steady-state conditions. These findings are supported by DFT calculations, which show the driving force and final structure for the surface metal protrusion to be metal-dependent, but point to an equivalent octahedral-coordinated M4+ carbonate species as the resting state in all cases. Experimentally, apparent reaction activation energies in the range of 96 +/- 19 kJ/mol are determined, with Pt leading to the lowest energy barrier. The results indicate that, for monatomic sites in SACs, differences in CO oxidation reactivity enforceable via metal selection are of lower magnitude than those evidenced previously through the mechanistic involvement of adjacent redox centers on the oxide carrier, suggesting that tuning of the oxide surface chemistry is as relevant as the selection of the supported metal.XAS experiments were performed at B18 beamline, Diamond Light Source, United Kingdom (proposals Nr. SP17377 and SP19072) and BL22 beamline, ALBA Light Source, Spain (experiment 2019023278). Beamline scientists D. Gianolio (Diamond) and L. Simonelli and C. Marini (ALBA) are acknowledged for their assistance with the beamline setup during XAS experiments. The authors are grateful to M. Garcia, E. Andres, M. E. Martinez, and I. Lopez (ITQ) for assistance during the XAS experiments. J. Ternieden (MPIKOFO) is acknowledged for the performance of XRD experiments. J.M. Salas (ITQ) is acknowledged for his experimental contribution to the CO-FTIR studies, and M.D. Soriano and A. Munoz for the recording of XP spectra. P.N.P. and F.S. acknowledge support by the state of BademWurttemberg through bwHPC (bwUnicluster and JUSTUS, RV bw17D01) and support from the Helmholtz Association is also gratefully acknowledged. This research received funding from the Alexander von Humboldt Foundation (postdoctoral grant to B.B.S.), the Max Planck Society and the Fonds der Chemischen Industry (FCI, Germany). The authors are grateful to Prof. Ferdi Schuth for the provision of lab facilities and support throughout the project. Funding from the Spanish Ministry of Science, Innovation and Universities (projects SEV 2016-0683 and RTI2018-096399-A-100) is also acknowledged.Sarma, BB.; Plessow, PN.; Agostini, G.; Concepción Heydorn, P.; Pfänder, N.; Kang, L.; Wang, FR.... (2020). Metal-Specific Reactivity in Single-Atom Catalysts: CO Oxidation on 4d and 5d Transition Metals Atomically Dispersed on MgO. Journal of the American Chemical Society. 142(35):14890-14902. https://doi.org/10.1021/jacs.0c03627S148901490214235Ruckenstein, E., & Hu, X. D. (1985). Mechanism of redispersion of supported metal catalysts in oxidative atmospheres. Langmuir, 1(6), 756-760. doi:10.1021/la00066a019Szymura, J. A. (1986). Studies on Redispersion and Stability of Platinum in Pt/MgO System during Oxygen Treatment at High Temperatures. Zeitschrift f�r anorganische und allgemeine Chemie, 542(11), 232-240. doi:10.1002/zaac.19865421130Morgan, K., Goguet, A., & Hardacre, C. (2015). Metal Redispersion Strategies for Recycling of Supported Metal Catalysts: A Perspective. ACS Catalysis, 5(6), 3430-3445. doi:10.1021/acscatal.5b00535Qiao, B., Wang, A., Yang, X., Allard, L. F., Jiang, Z., Cui, Y., … Zhang, T. (2011). Single-atom catalysis of CO oxidation using Pt1/FeOx. Nature Chemistry, 3(8), 634-641. doi:10.1038/nchem.1095Jones, J., Xiong, H., DeLaRiva, A. T., Peterson, E. J., Pham, H., Challa, S. R., … Datye, A. K. (2016). Thermally stable single-atom platinum-on-ceria catalysts via atom trapping. Science, 353(6295), 150-154. doi:10.1126/science.aaf8800Kunwar, D., Zhou, S., DeLaRiva, A., Peterson, E. J., Xiong, H., Pereira-Hernández, X. I., … Datye, A. K. (2019). Stabilizing High Metal Loadings of Thermally Stable Platinum Single Atoms on an Industrial Catalyst Support. ACS Catalysis, 9(5), 3978-3990. doi:10.1021/acscatal.8b04885Liu, L., Zakharov, D. N., Arenal, R., Concepcion, P., Stach, E. A., & Corma, A. (2018). Evolution and stabilization of subnanometric metal species in confined space by in situ TEM. Nature Communications, 9(1). doi:10.1038/s41467-018-03012-6Sarma, B. B., Kim, J., Amsler, J., Agostini, G., Weidenthaler, C., Pfänder, N., … Prieto, G. (2020). One‐Pot Cooperation of Single‐Atom Rh and Ru Solid Catalysts for a Selective Tandem Olefin Isomerization‐Hydrosilylation Process. Angewandte Chemie International Edition, 59(14), 5806-5815. doi:10.1002/anie.201915255Yang, X.-F., Wang, A., Qiao, B., Li, J., Liu, J., & Zhang, T. (2013). Single-Atom Catalysts: A New Frontier in Heterogeneous Catalysis. Accounts of Chemical Research, 46(8), 1740-1748. doi:10.1021/ar300361mGates, B. C., Flytzani-Stephanopoulos, M., Dixon, D. A., & Katz, A. (2017). Atomically dispersed supported metal catalysts: perspectives and suggestions for future research. Catalysis Science & Technology, 7(19), 4259-4275. doi:10.1039/c7cy00881cWang, A., Li, J., & Zhang, T. (2018). Heterogeneous single-atom catalysis. Nature Reviews Chemistry, 2(6), 65-81. doi:10.1038/s41570-018-0010-1Amsler, J., Sarma, B. B., Agostini, G., Prieto, G., Plessow, P. N., & Studt, F. (2020). Prospects of Heterogeneous Hydroformylation with Supported Single Atom Catalysts. Journal of the American Chemical Society, 142(11), 5087-5096. doi:10.1021/jacs.9b12171Cui, X., Li, W., Ryabchuk, P., Junge, K., & Beller, M. (2018). Bridging homogeneous and heterogeneous catalysis by heterogeneous single-metal-site catalysts. Nature Catalysis, 1(6), 385-397. doi:10.1038/s41929-018-0090-9Uzun, A., Ortalan, V., Browning, N. D., & Gates, B. C. (2010). A site-isolated mononuclear iridium complex catalyst supported on MgO: Characterization by spectroscopy and aberration-corrected scanning transmission electron microscopy. Journal of Catalysis, 269(2), 318-328. doi:10.1016/j.jcat.2009.11.017Chen, Y., Ji, S., Sun, W., Chen, W., Dong, J., Wen, J., … Li, Y. (2018). Discovering Partially Charged Single-Atom Pt for Enhanced Anti-Markovnikov Alkene Hydrosilylation. Journal of the American Chemical Society, 140(24), 7407-7410. doi:10.1021/jacs.8b03121Zhang, X., Sun, Z., Wang, B., Tang, Y., Nguyen, L., Li, Y., & Tao, F. F. (2018). C–C Coupling on Single-Atom-Based Heterogeneous Catalyst. Journal of the American Chemical Society, 140(3), 954-962. doi:10.1021/jacs.7b09314Chen, Z., Vorobyeva, E., Mitchell, S., Fako, E., Ortuño, M. A., López, N., … Pérez-Ramírez, J. (2018). A heterogeneous single-atom palladium catalyst surpassing homogeneous systems for Suzuki coupling. Nature Nanotechnology, 13(8), 702-707. doi:10.1038/s41565-018-0167-2Millet, M.-M., Algara-Siller, G., Wrabetz, S., Mazheika, A., Girgsdies, F., Teschner, D., … Frei, E. (2019). Ni Single Atom Catalysts for CO2 Activation. Journal of the American Chemical Society, 141(6), 2451-2461. doi:10.1021/jacs.8b11729Li, J., Guan, Q., Wu, H., Liu, W., Lin, Y., Sun, Z., … Lu, J. (2019). Highly Active and Stable Metal Single-Atom Catalysts Achieved by Strong Electronic Metal–Support Interactions. Journal of the American Chemical Society, 141(37), 14515-14519. doi:10.1021/jacs.9b06482Tang, Y., Wei, Y., Wang, Z., Zhang, S., Li, Y., Nguyen, L., … Hu, P. (2019). Synergy of Single-Atom Ni1 and Ru1 Sites on CeO2 for Dry Reforming of CH4. Journal of the American Chemical Society, 141(18), 7283-7293. doi:10.1021/jacs.8b10910Malta, G., Kondrat, S. A., Freakley, S. J., Davies, C. J., Lu, L., Dawson, S., … Hutchings, G. J. (2017). Identification of single-site gold catalysis in acetylene hydrochlorination. Science, 355(6332), 1399-1403. doi:10.1126/science.aal3439Falsig, H., Hvolbæk, B., Kristensen, I. S., Jiang, T., Bligaard, T., Christensen, C. H., & Nørskov, J. K. (2008). Trends in the Catalytic CO Oxidation Activity of Nanoparticles. Angewandte Chemie International Edition, 47(26), 4835-4839. doi:10.1002/anie.200801479Latimer, A. A., Kulkarni, A. R., Aljama, H., Montoya, J. H., Yoo, J. S., Tsai, C., … Nørskov, J. K. (2016). Understanding trends in C–H bond activation in heterogeneous catalysis. Nature Materials, 16(2), 225-229. doi:10.1038/nmat4760Hensen, E. J. M., Brans, H. J. A., Lardinois, G. M. H. J., de Beer, V. H. J., van Veen, J. A. R., & van Santen, R. A. (2000). Periodic Trends in Hydrotreating Catalysis: Thiophene Hydrodesulfurization over Carbon-Supported 4d Transition Metal Sulfides. Journal of Catalysis, 192(1), 98-107. doi:10.1006/jcat.2000.2824Thornburg, N. E., Thompson, A. B., & Notestein, J. M. (2015). Periodic Trends in Highly Dispersed Groups IV and V Supported Metal Oxide Catalysts for Alkene Epoxidation with H2O2. ACS Catalysis, 5(9), 5077-5088. doi:10.1021/acscatal.5b01105Yang, T., Fukuda, R., Hosokawa, S., Tanaka, T., Sakaki, S., & Ehara, M. (2017). A Theoretical Investigation on CO Oxidation by Single-Atom Catalysts M1 /γ-Al2 O3 (M=Pd, Fe, Co, and Ni). ChemCatChem, 9(7), 1222-1229. doi:10.1002/cctc.201601713Kropp, T., Lu, Z., Li, Z., Chin, Y.-H. C., & Mavrikakis, M. (2019). Anionic Single-Atom Catalysts for CO Oxidation: Support-Independent Activity at Low Temperatures. ACS Catalysis, 9(2), 1595-1604. doi:10.1021/acscatal.8b03298O’Connor, N. J., Jonayat, A. S. M., Janik, M. J., & Senftle, T. P. (2018). Interaction trends between single metal atoms and oxide supports identified with density functional theory and statistical learning. Nature Catalysis, 1(7), 531-539. doi:10.1038/s41929-018-0094-5Tanaka, I., Oba, F., Tatsumi, K., Kunisu, M., Nakano, M., & Adachi, H. (2002). Theoretical Formation Energy of Oxygen-Vacancies in Oxides. MATERIALS TRANSACTIONS, 43(7), 1426-1429. doi:10.2320/matertrans.43.1426Therrien, A. J., Hensley, A. J. R., Marcinkowski, M. D., Zhang, R., Lucci, F. R., Coughlin, B., … Sykes, E. C. H. (2018). An atomic-scale view of single-site Pt catalysis for low-temperature CO oxidation. Nature Catalysis, 1(3), 192-198. doi:10.1038/s41929-018-0028-2Lu, Y., Wang, J., Yu, L., Kovarik, L., Zhang, X., Hoffman, A. S., … Karim, A. M. (2018). Identification of the active complex for CO oxidation over single-atom Ir-on-MgAl2O4 catalysts. Nature Catalysis, 2(2), 149-156. doi:10.1038/s41929-018-0192-4Zhang, B., Asakura, H., & Yan, N. (2017). Atomically Dispersed Rhodium on Self-Assembled Phosphotungstic Acid: Structural Features and Catalytic CO Oxidation Properties. Industrial & Engineering Chemistry Research, 56(13), 3578-3587. doi:10.1021/acs.iecr.7b00376Wang, H., Liu, J.-X., Allard, L. F., Lee, S., Liu, J., Li, H., … Yang, M. (2019). Surpassing the single-atom catalytic activity limit through paired Pt-O-Pt ensemble built from isolated Pt1 atoms. Nature Communications, 10(1). doi:10.1038/s41467-019-11856-9Ravel, B., & Newville, M. (2005). ATHENA,ARTEMIS,HEPHAESTUS: data analysis for X-ray absorption spectroscopy usingIFEFFIT. Journal of Synchrotron Radiation, 12(4), 537-541. doi:10.1107/s0909049505012719Perdew, J. P., Burke, K., & Ernzerhof, M. (1997). Generalized Gradient Approximation Made Simple [Phys. Rev. Lett. 77, 3865 (1996)]. Physical Review Letters, 78(7), 1396-1396. doi:10.1103/physrevlett.78.1396Grimme, S., Antony, J., Ehrlich, S., & Krieg, H. (2010). A consistent and accurate ab initio parametrization of density functional dispersion correction (DFT-D) for the 94 elements H-Pu. The Journal of Chemical Physics, 132(15), 154104. doi:10.1063/1.3382344Kresse, G., & Furthmüller, J. (1996). Efficient iterative schemes forab initiototal-energy calculations using a plane-wave basis set. Physical Review B, 54(16), 11169-11186. doi:10.1103/physrevb.54.11169Kresse, G., & Joubert, D. (1999). From ultrasoft pseudopotentials to the projector augmented-wave method. Physical Review B, 59(3), 1758-1775. doi:10.1103/physrevb.59.1758Plessow, P. N. (2018). Efficient Transition State Optimization of Periodic Structures through Automated Relaxed Potential Energy Surface Scans. Journal of Chemical Theory and Computation, 14(2), 981-990. doi:10.1021/acs.jctc.7b01070Hoffman, A. S., Debefve, L. M., Zhang, S., Perez-Aguilar, J. E., Conley, E. T., Justl, K. R., … Gates, B. C. (2018). Beating Heterogeneity of Single-Site Catalysts: MgO-Supported Iridium Complexes. ACS Catalysis, 8(4), 3489-3498. doi:10.1021/acscatal.8b00143Ren, Y., Tang, Y., Zhang, L., Liu, X., Li, L., Miao, S., … Zhang, T. (2019). Unraveling the coordination structure-performance relationship in Pt1/Fe2O3 single-atom catalyst. Nature Communications, 10(1). doi:10.1038/s41467-019-12459-0Gatla, S., Aubert, D., Agostini, G., Mathon, O., Pascarelli, S., Lunkenbein, T., … Kaper, H. (2016). Room-Temperature CO Oxidation Catalyst: Low-Temperature Metal–Support Interaction between Platinum Nanoparticles and Nanosized Ceria. ACS Catalysis, 6(9), 6151-6155. doi:10.1021/acscatal.6b00677Guan, H., Lin, J., Qiao, B., Yang, X., Li, L., Miao, S., … Zhang, T. (2016). Catalytically Active Rh Sub-Nanoclusters on TiO2 for CO Oxidation at Cryogenic Temperatures. Angewandte Chemie International Edition, 55(8), 2820-2824. doi:10.1002/anie.201510643Gaudet, J. R., de la Riva, A., Peterson, E. J., Bolin, T., & Datye, A. K. (2013). Improved Low-Temperature CO Oxidation Performance of Pd Supported on La-Stabilized Alumina. ACS Catalysis, 3(5), 846-855. doi:10.1021/cs400024uGänzler, A. M., Casapu, M., Doronkin, D. E., Maurer, F., Lott, P., Glatzel, P., … Grunwaldt, J.-D. (2019). Unravelling the Different Reaction Pathways for Low Temperature CO Oxidation on Pt/CeO2 and Pt/Al2O3 by Spatially Resolved Structure–Activity Correlations. The Journal of Physical Chemistry Letters, 10(24), 7698-7705. doi:10.1021/acs.jpclett.9b02768Nie, L., Mei, D., Xiong, H., Peng, B., Ren, Z., Hernandez, X. I. P., … Wang, Y. (2017). Activation of surface lattice oxygen in single-atom Pt/CeO 2 for low-temperature CO oxidation. Science, 358(6369), 1419-1423. doi:10.1126/science.aao2109Carrasco, J., Lopez, N., Illas, F., & Freund, H.-J. (2006). Bulk and surface oxygen vacancy formation and diffusion in single crystals, ultrathin films, and metal grown oxide structures. The Journal of Chemical Physics, 125(7), 074711. doi:10.1063/1.2335842Kropp, T., & Mavrikakis, M. (2019). Brønsted–Evans–Polanyi relation for CO oxidation on metal oxides following the Mars–van Krevelen mechanism. Journal of Catalysis, 377, 577-581. doi:10.1016/j.jcat.2019.08.002Martínez, J. I., Hansen, H. A., Rossmeisl, J., & Nørskov, J. K. (2009). Formation energies of rutile metal dioxides using density functional theory. Physical Review B, 79(4). doi:10.1103/physrevb.79.045120Soave, R., & Pacchioni, G. (2000). New bonding mode of CO on stepped MgO surfaces from density functional cluster model calculations. Chemical Physics Letters, 320(3-4), 345-351. doi:10.1016/s0009-2614(00)00246-3Sterrer, M., Risse, T., & Freund, H.-J. (2006). CO adsorption on the surface of MgO(001) thin films. Applied Catalysis A: General, 307(1), 58-61. doi:10.1016/j.apcata.2006.03.007Trionfetti, C., Babich, I. V., Seshan, K., & Lefferts, L. (2008). Presence of Lithium Ions in MgO Lattice: Surface Characterization by Infrared Spectroscopy and Reactivity towards Oxidative Conversion of Propane. Langmuir, 24(15), 8220-8228. doi:10.1021/la8006316Mihaylov, M. Y., Fierro-Gonzalez, J. C., Knözinger, H., Gates, B. C., & Hadjiivanov, K. I. (2006). Formation of Nonclassical Carbonyls of Au3+ in Zeolite NaY:  Characterization by Infrared Spectroscopy. The Journal of Physical Chemistry B, 110(15), 7695-7701. doi:10.1021/jp057426qWang, C., Bley, B., Balzer-Jöllenbeck, G., Lewis, A. R., Siu, S. C., Willner, H., & Aubke, F. (1995). New homoleptic metal carbonyl cations: the syntheses, vibrational and13C MAS NMR spectra of hexacarbonyl-ruthenium(II) and-osmium(II) undecafluorodiantimonate(V), [Ru(CO)6][Sb2F11]2and [Os(CO)6][Sb2F11]2. J. Chem. Soc., Chem. Commun., (20), 2071-2072. doi:10.1039/c39950002071Fukuda, Y., & Tanabe, K. (1973). Infrared Study of Carbon Dioxide Adsorbed on Magnesium and Calcium Oxides. 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Statistical features of edge turbulence in RFX-mod from Gas Puffing Imaging

Plasma density fluctuations in the edge plasma of the RFX-mod device are measured through the Gas Puffing Imaging Diagnostics. Statistical features of the signal are quantified in terms of the Probability Distribution Function (PDF), and computed for several kinds of discharges. The PDFs from discharges without particular control methods are found to be adequately described by a Gamma function, consistently with the recent results by Graves et al [J.P. Graves, et al, Plasma Phys. Control. Fusion 47, L1 (2005)]. On the other hand, pulses with external methods for plasma control feature modified PDFs. A first empirical analysis suggests that they may be interpolated through a linear combination of simple functions. An inspection of the literature shows that this kind of PDFs is common to other devices as well, and has been suggested to be due to the simultaneous presence of different mechanisms driving respectively coherent bursts and gaussian background turbulence. An attempt is made to relate differences in the PDFs to plasma conditions such as the local shift of the plasma column. A simple phenomenological model to interpret the nature of the PDF and assign a meaning to its parameters is also developed.Comment: 27 pages. Published in PPC

Scrape-off Layer Transport and Filament Characteristics in High-density Tokamak Regimes

A detailed cross-device investigation on the role of filamentary dynamics in high-density regimes has been performed within the EUROfusion framework, comparing the ASDEX Upgrade (AUG) and TCV tokamaks. Both devices run density ramp experiments at different levels of plasma current, keeping the toroidal field or q 95 constant in order to disentangle the role of the parallel connection length and the current. During the scan at a constant toroidal field, in both devices the scrape-off layer (SOL) profiles tend to develop a clear SOL density shoulder at a lower edge density whenever the current is reduced. Different current behaviour is substantially reconciled in terms of the edge density normalized to the Greenwald fraction. During the scan at constant q 95 AUG exhibits similar behaviour, whereas in TCV no upstream profile modification signature has been observed at lower current levels. The latter behaviour has been ascribed to the lack of target density rollover. The relation between the upstream density profile modification and detachment condition has been investigated. For both devices the relation between blob size and the SOL density e-folding length is found independent of the plasma current, with the observation of a clear increase in blob size and the edge density normalized to a Greenwald fraction. ASDEX Upgrade has also explored filamentary behaviour in the H-mode. The experiments in AUG have focused on the role of neutrals, performing discharges with and without cryogenic pumps, highlighting how high neutral pressure, not only in the divertor but also at the midplane, is needed in order to develop an H-mode SOL profile shoulder in AUG.Euratom research and training programme 2014-2018 633053Euratom research and training programme 2019-2020 633053Swiss National Science Foundation AT-0063United States Department of Energy DE-SC001052

Individual variation in orientation promotes a 3000-km latitudinal change in wintering grounds in a long-distance migratory raptor

Migrating juvenile birds rely on endogenous information in choosing the direction in which to fly, but such input may be overridden by social interactions with experienced individuals. We tagged seven juvenile Short-toed Eagles Circaetus gallicus with GPS transmitters in southern Italy. This trans-Saharan migrant flies mainly by soaring and is therefore not well adapted to performing long water crossings. Five of the seven tagged juveniles used the longer but apparently safer route towards the Strait of Gibraltar, and two migrated along a southerly trajectory and subsequently spent the winter in Sicily, apparently forced to do so by the 150-km-wide Sicily Channel. One of these individuals took the longer route the following autumn. These results, combined with long-term (15 years) visual field observations involving thousands of individuals, suggest that inexperienced Short-toed Eagles may learn their migratory routes from experienced adults, whereas some of them migrate south in response to an innate orientation instinct. Transport costs, inherited information and geography apparently interact, forcing some Short-toed Eagles to winter 3000 km to the north of the majority of their conspecifics.The study has been funded by the Osservatorio Faunistico of Regione Basilicata through the Parco Regionale Gallipoli Cognato – Piccole Dolomiti Lucane