Search for dissertations about: "Sheath"

Showing result 1 - 5 of 56 swedish dissertations containing the word Sheath.

  2. 1. Modelling of cathode-plasma interaction in short high-intensity electric arc : Application to Gas Tungsten Arc Welding

    Author : Alireza Javidi Shirvan; Isabelle Choquet; Håkan Nilsson; Armelle Vardelle; Högskolan Väst; []
    Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; NATURVETENSKAP; NATURAL SCIENCES; Electric arc discharge; sheath; pre-sheath; Knudsen layer; doped refractory cathode; arc-cathode coupling; Gas Tungsten Arc simulation; OpenFOAM.; Production Technology; Produktionsteknik; Manufacturing and materials engineering; Produktions- och materialteknik;

    Abstract : In arc welding the quality of the weld is strongly influenced by the thermal history of the workpiece which is itself governed by the electric arc heat source. The models for predicting weld properties thus need a good evaluation of the distribution of the heat input from thearc to the workpiece. READ MORE

  4. 2. Detector Development, Source Characterization and Novel Applications of Laser Ion Acceleration

    Author : Lovisa Senje; Atomfysik; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Laser; Ion; Acceleration; Proton; Water; Sheath; Lifetime; Laser; Ion; Acceleration; Proton; Water; Radiolysis; Sheath; Detector; Fysicumarkivet A:2017:Senje;

    Abstract : The main focus of the work presented in this thesis is on experimental studies oflaser acceleration of protons and other positive ions from solid targets. The topic is explored from three different angles: firstly, the development of diagnostics adapted to the ion pulses, secondly, the characterization of the source of the energetic particles and, finally, the application of laser-accelerated protons for time-resolved radiolysis of glass and water. READ MORE

  5. 3. Laser-Driven Particle Acceleration - Improving Performance Through Smart Target Design

    Author : Matthias Burza; Atomfysik; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; wakefield; ultra-relativistic; ultra-intense; TNSA; Terawatt; sheath; proton; polarimetry; plasma mirror; plasma; Petawatt; particle; oscillation; Normarski; micromachining; LWFA; laser; interferometry; electron; contrast; acceleration; bubble; Fysicumarkivet A:2012:Burza;

    Abstract : Laser-driven particle acceleration makes use of sub-picosecond, pulsed, high-power laser systems, capable of producing intensities ~10^{19} W/cm^2 at the laser focus to form plasmas, and use ultra-relativistic and nonlinear dynamics to produce quasistatic acceleration fields. This allows electrons to be accelerated to ~100 MeV over sub-centimetre distances, while protons may be accelerated to the ~10 MeV regime. READ MORE

  6. 4. Modelling of Electric Arc Welding : arc-electrode coupling

    Author : Alireza Javidi Shirvan; Isabelle Choquet; Håkan Nilsson; Alexei Heintz; Högskolan Väst; []
    Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; electric welding; arc welding simulation; electrode; plasma; cathode layer; sheath; arc discharge; Manufacturing and materials engineering; Produktions- och materialteknik;

    Abstract : Arc welding still requires deeper process understanding and more accurateprediction of the heat transferred to the base metal. This can be provided by CFD modelling.Most works done to model arc discharge using CFD consider the arc corealone. READ MORE

  7. 5. Target and Laser Pulse Optimization for Laser-Driven Ion Acceleration

    Author : Alexander Permogorov; Atomfysik; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Terawatt laser; Target normal sheath acceleration; laser-driven ion acceleration; proton acceleration; double plasma mirror; Thomson parabola spectrometer; Fysicumarkivet A:2021:Permogorov;

    Abstract : The research presented in this thesis is primarily focused on experimental investigations of laser-driven ion acceleration from solid targets via the target normal sheath acceleration mechanism. In particular, ways of optimizing the absorption of the laser pulse energy by free plasma electrons in the target, or modifying the shape of the accelerating electron sheath were addressed. READ MORE