Sökning: "ion velocity"

Visar resultat 16 - 20 av 63 avhandlingar innehållade orden ion velocity.

1. 16. Beyond scattering – what more can be learned from pulsed keV ion beams?

   Författare :Svenja Lohmann; Daniel Primetzhofer; Andreas Wucher; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Charge exchange; Deep UV photons; Electron emission; Silicon; Sputtering; TOF-MEIS; Fysik; Physics;

   Sammanfattning : Interactions of energetic ions with matter govern processes as diverse as the influence of solar wind, hadron therapy for cancer treatment and plasma-wall interactions in fusion devices, and are used for controlled manipulation of materials properties as well as analytical methods. The scattering of ions from target nuclei and electrons does not only lead to energy deposition, but can induce the emission of different secondary particles including electrons, photons, sputtered target ions and neutrals as well as nuclear reaction products. LÄS MER

3. 17. Cluster Observations and Theoretical Explanations of Broadband Waves in the Auroral Region

   Författare :Marie Backrud; Jan-Erik Wahlund; Mats André; David Knudsen; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Space and plasma physics; ion acoustic waves; auroral region; anomalous resistivity; Cluster; Rymd- och plasmafysik; Space physics; Rymdfysik;

   Sammanfattning : Broadband extremely low-frequency wave emissions below the ion plasma frequency have been observed by a number of spacecraft and rockets on auroral field lines. The importance of these broadband emissions for transverse ion heating and electron acceleration in the auroral regions is now reasonably well established. LÄS MER

4. 18. Fast wave heating and current drive in tokamaks

   Författare :Martin Laxåback; Torbjörn Hellsten; Raymond Koch; KTH; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Tokamak; JET; ITER; thermonuclear fusion; fast wave; heating; current drive; ion cyclotron resonance; polychromatic; finite orbit widths; RF-induced transport; neutral beam injection; fusion born alpha particles; magnetosonic eigenmodes; parasitic absorption; modelling; weighted Monte Carlo scheme; Fysik; Physics; Fysik;

   Sammanfattning : This thesis concerns heating and current drive in tokamak plasmas using the fast magnetosonic wave in the ion cyclotron range of frequencies. Fast wave heating is a versatile heating method for thermonuclear fusion plasmas and can provide both ion and electron heating and non-inductive current drive. LÄS MER

5. 19. Neutron Emission Spectrometry for Fusion Reactor Diagnosis : Method Development and Data Analysis

   Författare :Jacob Eriksson; Göran Ericsson; Carl Hellesen; Sean Conroy; Andreas Dinklage; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; fusion; plasma diagnostics; neutron spectrometry; TOFOR; MPRu; tokamak; JET; fast ions; fuel ion density; relativistic kinematics; Fysik med inriktning mot tillämpad kärnfysik; Physics with specialization in Applied Nuclear Physics;

   Sammanfattning : It is possible to obtain information about various properties of the fuel ions deuterium (D) and tritium (T) in a fusion plasma by measuring the neutron emission from the plasma. Neutrons are produced in fusion reactions between the fuel ions, which means that the intensity and energy spectrum of the emitted neutrons are related to the densities and velocity distributions of these ions. LÄS MER

7. 20. InP-based photonic crystals : Processing, Material properties and Dispersion effects

   Författare :Audrey Berrier; Srinivasan Anand; Alfred Forchel; KTH; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Photonic crystals; indium phosphide; photonic bandgap; Bloch modes; slow light; dispersion; coupled cavity waveguides; chemically assisted ion beam etching; lag effect; cavities; optical losses; carrier transport; carrier lifetimes; negative refraction; photonic bandstructure; Physics; Fysik;

   Sammanfattning : Photonic crystals (PhCs) are periodic dielectric structures that exhibit a photonic bandgap, i.e., a range of wavelength for which light propagation is forbidden. The special band structure related dispersion properties offer a realm of novel functionalities and interesting physical phenomena. LÄS MER