Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 44 for “"particle acceleration"”.
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Laser-Produced Plasmas for Particle Acceleration
… that aim to stabilise and optimise laser-based particle accelerators. The technique is called laser wakefield acceleration, where electric fields of the order of 102 GV/m accelerate electrons to high energies (⇠102 MeV) over mm-distances in laser-produced plasmas. Among the prerequisites for …
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High Power Microwave Generation for Advanced Particle Acceleration
… sources for application to high gradient particle accelerators. The major effort was directed at the design and successful test of a metamaterial-based power extractor at the Argonne Wakefield Accelerator (AWA). We obtained up to 565 MW, 2.7 ns (FWHM) pulses at 11.7 GHz from the structure. …
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Topics in Energy Release and Particle Acceleration in the Heliosphere
… the release of energy in solar flares, and the acceleration and transport of particles in various astrophysical situations. While numerical simulations are central to this thesis, these are always motivated by analytical arguments. A review of flare energy release is given in Chapter 2, with …
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Laser-Driven Particle Acceleration - Improving Performance Through Smart Target Design
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 …
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Particle acceleration at null-point current sheets in the solar corona
… geometries of reconnecting fields within which particle acceleration can be simulated. A code was written to use a predictor-corrector algorithm to model the full motion of particles in such fields, switching to a Runge-Kutta guiding-centre scheme (adapted from the the St Andrews party orb …
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Hard X-ray diagnostics of particle acceleration and energy release in solar flares and coronal jets
Understanding the origins of energetic particles in the near-earth space environment is a fundamental problem of heliophysics research. This dissertation investigates two forms of solar activity capable of accelerating particles to high energies—solar flares and coronal jets, both of which are …
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Investigation of laser-driven particle acceleration for the development of tunable ion sources for applications in high energy density science
… the use of these high-intensity lasers to drive particle beams. Possible applications of these particle sources include isotope production for medical applications, proton cancer therapy, and fusion energy schemes. This thesis focuses on laser-driven proton acceleration and adds to the existing …
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Experimental Investigation of Particle Lag behind a Shock Wave using a Novel Laser Doppler Accelerometer
Determination of particle slip is a major concern for particle based measurements in un- heated supersonic facilities, as it is a limiting factor for the instruments' frequency response. For the purpose of determining the particle deceleration through a stationary shock wave in a super sonic …
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Predicting Motion of Engine-Ingested Particles Using Deep Neural Networks
… to facilitate the design of gas turbine engine particle separators by reducing the computational expense to accurately simulate the fluid flow and particle motion inside the separator. It has been well-documented that particle ingestion yields many detrimental impacts for gas turbine engines. …
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An analysis of reconnection dynamics in an eruptive flare model
… are considerably more efficient at producing particle acceleration than previously thought since the efficiency of particle acceleration at shocks increases dramatically with Mach number. We compare this model with numerical simulations by T. Yokoyama & K. Shibata and find good agreement.</p>
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Investigating the cosmic-ray ionization rate in the galactic interstellar medium through observations of H3+
… spectra require a large flux of low-energy (MeV) particles to reproduce values inferred from observations. Given the relatively short range of low-energy cosmic rays --- those most efficient at ionization --- the proximity of a cloud to a site of particle acceleration may set its ionization rate. …
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Energy partition in magnetic reconnection and kinetic turbulence in weakly collisional plasmas
… is how magnetic energy is dissipated into particle heating, kinetic energy, and supra-thermal particle acceleration; an understanding of energy partition in reconnection may be used to explain numerous physical phenomena such as the turbulent heating of the solar wind and the formation of …
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Modeling Magnetic Field Amplification in Nonlinear Diffusive Shock Acceleration
… self-consistently coupled to efficient shock acceleration of charged particles. Based on a Monte Carlo simulation of particle transport and acceleration in nonlinear shocks, the model describes magnetic field amplification using the state-of-the-art analytic models of instabilities in …
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Novel approach to laser-driven multi-stage ion acceleration
All-optical approaches to particle acceleration are currently attracting a significant research effort internationally. Key to the interest in a laser based particle accelerator lies in its cost effective and compactness. However, the ion beams accelerated by the laser-driven mechanisms have …
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Gamma-Ray Observations of X-ray Binaries
… emission, thus improving our knowledge of particle acceleration and radiative processes in the jets. The implications have far reaching consequences on the understanding of other XRBs and microquasars and also of active galactic nuclei, which are in many ways similar to microquasars and are …
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Full Mueller imaging: direction dependent corrections in polarimetric radio imaging
… have magnetism at their heart, be it cosmic ray particle acceleration, star formation, or the launch of radio galaxy jets, pulsars, etc. One key fundamental process that allows us to detect and characterize cosmic magnetic fields with radio astronomy is the polarization of synchrotron radiation. …
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