1,358 research outputs found

    Characterization of self-injected electron beams from LWFA experiments at SPARC_LAB

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    The plasma-based acceleration is an encouraging technique to overcome the limits of the accelerating gradient in the conventional RF acceleration. A plasma accelerator is able to provide accelerating fields up to hundreds of GeV/mGeV/m, paving the way to accelerate particles to several MeV over a short distance (below the millimetre range). Here the characteristics of preliminary electron beams obtained with the self-injection mechanism produced with the FLAME high-power laser at the SPARC_LAB test facility are shown. In detail, with an energy laser on focus of 1.5¬†J1.5\ J and a pulse temporal length (FWHM) of 40¬†fs40\ fs, we obtained an electron plasma density due to laser ionization of about 6√ó1018¬†cm‚ąí36 \times 10^{18}\ cm^{-3}, electron energy up to 350¬†MeV350\ MeV and beam charge in the range (50‚ąí100)¬†pC(50 - 100)\ pC.Comment: 6 pages, 11 figures, conference EAAC201

    On the welding of different materials by diode laser

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    In technical literature, there are few papers about the use of diode lasers in material processing and particularly in metal welding. In this paper, different materials, according to specific and particular industrial needs and requests, have been tested with a welding process by a diode laser, emitting a 808 nm laser radiation. Beads on plate have been studied. The goal was to evaluate the maximum weldable thickness and define the best process parameters for each material. The experimental evaluation has been carried out considering the following parameters: power level, welding speed (WS), shielding gas, gas nozzle and orientation of the focused elliptical spot as to the welding direction

    Diversidade e distribuição espacial de bromeliáceas epifíticas do Altíssimo Rio Tibagi - Paraná - Brasil.

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    O presente estudo teve como objetivo caracterizar a diversidade e a distribui√ß√£o espacial das bromeli√°ceas epif√≠ticas na regi√£o do alt√≠ssimo rio Tibagi, considerando os fatores geomorfol√≥gicos, pedol√≥gicos, clim√°ticos e vegetacionais. A avalia√ß√£o fitossociol√≥gica das bromeli√°ceas foi realizada mediante instala√ß√£o de parcelas em n√ļmero vari√°vel nas tr√™s √°reas de estudo. O levantamento flor√≠stico foi complementado por observa√ß√Ķes nas √°reas adjacentes √†s parcelas, respeitando a compartimenta√ß√£o geomorfol√≥gica, pedol√≥gica e vegetacional. Foram registradas onze esp√©cies de bromeli√°ceas no total, tendo sido sete delas observadas na √°rea da cabeceira do rio Tibagi, oito no c√Ęnion e nove na floresta da foz do rio Bugio. A riqueza foi relacionada, principalmente, com as condi√ß√Ķes macro e microclim√°ticas. A umidade fornecida pelas nuvens e chuvas formadas na cuesta do segundo planalto, assim como, em microescala, a umidade atmosf√©rica gerada pelas cachoeiras existentes no c√Ęnion e originada da evapora√ß√£o da √°gua dos Organossolos, √© o fator clim√°tico fundamental na defini√ß√£o dos padr√Ķes encontrados. Considerando a distribui√ß√£o horizontal das esp√©cies, a diminui√ß√£o de bromeli√°ceas da por√ß√£o mais pr√≥xima ao canal para a mais distante est√° atrelada ao gradiente microclim√°tico, formado pela redu√ß√£o em umidade relativa associada √† diminui√ß√£o em luminosidade
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