Fast magnetosonic waves in the ion cyclotron range of frequencies have the potential to heat plasma and drive current in a thermonuclear fusion reactor. A code, SELFO-light, has been developed to study the physics of ion cyclotron resonantheating and current drive in thermonuclear fusion reactors. It uses a global full wave solver LION and a new 1D Fokker-Planck solver for the self-consistent calculations of the wave field and the distribution function of ions.In present day tokamak experiments like DIII-D and JET, fast wave damping by ions at higher harmonic cyclotron frequencies is weak compared to future thermonuclear tokamak reactors like DEMO. The strong damping by deuterium, tritium and thermonuclear alpha-particles and the large Doppler width of fast alpha-particles in DEMO makes it difficult to drive the current when harmonic resonance layers of these ionspecies are located at low field side of the magnetic axis. At higher harmonic frequencies the possibility of fast wave current drive diminishes due to the overlapping of alpha-particle harmonic resonance layers. Narrow frequency bands suitable for the fast wave current drive in DEMO have been identified at lower harmonics of the alpha-particles. For these frequencies the effect of formation of high-energy tails in the distribution function of majority and minority ion species on the current drive have been studied. Some of these frequencies are found to provide efficient ion heating in the start up phase of DEMO. The spectrum where efficient current drive can be obtained is restricted due to weak electron damping at lower toroidal mode numbers and strong trapped electron damping at higher toroidal mode numbers. The width of toroidal mode spectra for which efficient current drive can be obtained have been identified, which has important implications for the antenna design. / <p>QC 20130327</p>

The main object of this work is the technology of radio frequency controlled inductively coupled plasma, abbreviated RF-ICP. The specific goal of the work was the application of surface layers of tungsten and analysis of the influence of changes in process conditions on the resulting microstructure and chemical composition of deposited coatings. The monitored conditions were torch power, choice of carrier gas, powder feedrate.

The increased effects of global warming have been a driving force to further research and develop sustainable energy sources, such as fusion. In this study, two different fusion devices are compared in terms of ion cyclotron resonance heating (ICRH)of plasma. The two devices are the tokamaks ASDEX Upgrade and not yet built ITER. To make the comparison, ICRH was simulated in the two tokamaks using the FEMIC code. ASDEXUpgrade was simulated with a deuterium plasma and ITER was simulated both with a deuterium and a deuterium-tritium plasma. In all scenarios a 3% minority species concentration,consisting of helium-3, was introduced. The obtained results showa higher and more centered wave absorption in ITER, compared to ASDEX Upgrade. This is mainly due to the size difference of the tokamaks. The smaller plasma radius of ASDEX Upgrade allowed for more wave reflection in the plasma, resulting in standing waves that formed eigenmode patterns. For simulationsin ITER, the waves were absorbed before they could be reflected in the plasma. Instead of standing waves and eigenmode patterns,the waves behaved as beams, propagating in a narrow region of the plasma. This indicates that ITER is more effective in terms of ICRH, as the absorption is greater and more focused to the center, minimizing power losses to the surroundings. / De ökade konsekvenserna av den globala uppvärmningen har varit en drivkraft för fortsatt forskning och utveckling av hållbara energikällor, bland annat fusion. I den här studien jämförs två olika fusionsanläggningar med avseende på joncyklotronresonansuppvärmning (ICRH) av plasma. De två anläggningarna är tokamakerna ASDEX Upgrade och ännu inte byggda ITER. För att göra jämförelser simulerades ICRH i de två tokamakerna med hjälp av FEMIC-koden. ASDEX Upgrade simulerades med ett deuteriumplasma och ITER simulerades med både ett deuteriumoch ett deuterium-tritiumplasma. För alla scenarier introducerades en 3% minoritetskoncentration av helium-3. Resultaten visar en högre och mer centrerad vågabsorption i ITER jämfört med ASDEX Upgrade. Detta beror framför allt på storleksskillnaden mellan tokamakerna. Den kortare plasmaradien av ASDEX Upgrade tillät mer reflektion i plasmat, vilket resulterade i stående vågor som bildade egenmodsmönster. För simuleringar i ITER absorberades vågorna innan de kunde reflekteras i plasmat. I stället för stående vågor och egenmodsmönster uppförde vågorna sig som strålar som propagerade över en smal region i plasmat. Det här indikerar att ITER är mer effektiv med avseende på ICRH, då absorptionen re och mer centrerad, vilket minimerar effektförluster till omgivningen. / Kandidatexjobb i elektroteknik 2022, KTH, Stockholm

Fusion energy has been said to be the solution to all the world’s energy problems. The International Thermonuclear Experimental Reactor (ITER) is the flagship project to demonstrate the feasibility of fusion energy. The Central Solenoid (CS), an important component of the reactor, is needed to induce plasma current, initiate, ramp-up, ramp-down, and sustain plasma in a very controlled manner. In order to achieve this, the CS coil packs must be manufactured under controlled conditions. The CS conductor is an advanced cable-in-conduit Nb3Sn superconductor. The CS cable will be made in long continuous sections but with thousands of meter of cable needed, splices will have to be made in the field during construction of the ITER reactor. With the ends of the CS cable being exposed to the environment for an unspecified amount of time, concern has been expressed about the effect of the cable exposure on the quality of the splice. As a result an experimental program was devised to replicate and expedite the environmental damage the cable may see while in the field. The CS cable samples were exposed to 100% humidity at 60, 80, and 100oC for periods ranging from one week to four weeks. Once the samples were soaked for a period of time they were then sintered as would be done in the field. After sintering the mechanical tests were done to determine the load required to push the sintered strands out of the copper sleeve. Initial results obtained with samples having the sleeve thickness of 1.25mm (0.05in) were inconclusive due to the presence of a fold in the copper sleeve formed during the compaction of the sleeve around the cable. To prevent the fold formation, another set of samples were prepared with thicker copper sleeve of 5mm (0.20in). Results from these samples yielded data that was more conclusive and showed a possible correlation between aging temperature and sintering strength. The experimental data suggests that the thin oxide layer formed during the elevated temperature soak at 100% humidity may even be beneficial to the sinter quality.

Over the past decade, fusion research has showed the potential of being a main candidate for energy production for future generations. Further advances in improved fusion performance are therefore vital. This thesis focuses on advanced fusion plasma scenarios and their diagnostic requirements. In particular the design of a motional Stark effect (MSE) diagnostic at the MAST spherical tokamak and the analysis of magneto-hydrodynamic mode feedback control and pulsed poloidal current drive (PPCD) at the reversed field pinch (RFP) experiment EXTRAP T2R are discussed. The MSE diagnostic is important for the determination of the plasma current profile, information that is necessary for studies in advanced confinement scenarios like reversed shear profiles or current holes. The MAST MSE system has two channels and selects the spectral components using 1Å FWHM interference filters. The diagnostic has been commissioned during the fall of 2006 and the results show the feasibility of the technique with rms-noise ~0.5° using a time resolution of 1 ms. Investigations of mirror labyrinths for the future ITER MSE diagnostic highlight the need for careful calibration considerations. Feedback control and PPCD are techniques for improved confinement. Feedback control dramatically decreases impurity influx at the end of discharges while transport in the bulk plasma is largely unaffected. During PPCD the transport is seen to decrease and it is demonstrated that PPCD and feedback control can be employed simultaneously. New and innovative techniques for fusion spectroscopy are furthermore described. This includes the use of correlations in line integrated signals to determine ion emission profiles in poloidally symmetric environments. Good agreement with other diagnostic methods is obtained. The assessment of electron temperature profiles using measured differences between Thomson scattering and vacuum ultra-violet spectroscopy is also shown. / QC 20100907

The understanding and modelling of heat and radiation transport in tokamak plasmas is essential in order to progress in the development of thermonuclear fusion towards a practical energy source which meets all the future needs of environment, safety, and fuel inexhaustibility. This activity enables prospective studies and design to be carried out for next step tokamaks. Due to the complexity of the exact calculation, synchrotron losses are usually estimated in such studies, with expressions derived from a plasma description using simplifying assumptions on the geometry, radiation absorption, density and temperature profiles. In this thesis, a complete formulation of the transport of synchrotron radiation is performed for realistic conditions of toroidal plasma geometry with elongated cross-section, using a precise method for the calculation of the absorption coefficients, and for arbitrary shapes of density and temperature profiles. In particular, this formulation is able to describe plasmas with arbitrary aspect ratios and with temperature profiles obtained in internal transport barrier regimes, which cannot be described accurately with the present expressions. As an illustration, we show that in the case of an advanced high-temperature plasma envisaged for a steady state D-T commercial reactor, synchrotron losses represent approximately 20% of the total losses. Considering the quantitative importance of the above effects and the significant magnitude of synchrotron losses in the thermal power balance of a D-T tokamak reactor plasma, a new fit for the fast calculation of the synchrotron radiation loss is proposed. Using this improved model in the thermal balance, prospective and sensitivity studies are performed for future tokamak projects, and the key issues which limit the performance are isolated. It is shown that, the most restrictive constraint for achieving higher plasma performance is the peak heat flux on the divertor plates. In non-inductive steady-state operation, advanced tokamak regimes are required to achieve relevant thermonuclear plasma performance for next step tokamaks and for a commercial reactor. In the frame of a multi-step strategy towards a commercial reactor, a superconducting next step tokamak compatible with the European budget possibilities is optimized. Considering both the plasma physics and the magnetic system technology and for a given aspect ratio, the smallest machine meeting the physical and technological requirements is determined. In a steady state tokamak commercial reactor, we show that there is an optimal value for the confinement enhancement factor which maximizes the plasma performance, for a given and also for the highest electrical power into the network. This highest electrical power meeting the stability requirements steadily decreases with the confinement enhancement factor. This effect is crucial because both a high plasma performance and a high enough electrical power into the network are required to minimize the cost of electricity, and consequently to make fusion energy more competitive.

A back scatter time of flight neutron spectrometer consisting of two scintillation detectors is simulated in Geant4 to examine whether it is possible to perform a proof of concept test at the NESSA facility at Uppsala University. An efficiency of ε = 2.45 · 10^-6 is shown to be large enough for a neutron generator intensity of 1.9 · 10^10 neutrons per second to achieve a minimal required signal count rate of 10000 counts per hour. A corresponding full width at half maximum energy resolution of 8.3% is found. The background in one of the detectors is simulated in MCNP and found to be a factor 62 larger than the signal for a given set of pulse height thresholds in the detectors. Measures to increase the signal to background ratio are discussed and an outlook for future work concerning testing the spectrometer at NESSA is presented.

Memoria (licenciado en ciencias jurídicas y sociales) / La presente investigación tiene como objetivo analizar sobre la eventual afectación de la responsabilidad penal de la víctima de trata de personas por la comisión del delito de tráfico de drogas en concreción al ánimo de explotación de la trata. De esta manera se realizará una descripción general orientada sobre el delito de trata de personas en nuestro ordenamiento, centrándose en ciertos elementos como lo son sus verbos rectores, medios comisivos y fines de explotación. Posteriormente tratamos la tipificación del ilícito de tráfico de drogas junto con su vinculación con el delito de trata, elementos necesarios para su ulterior análisis en cuanto a la eventual responsabilidad penal que pudiera tener la víctima respecto al cometer el delito de tráfico de drogas en el contexto de la trata. Finalmente, en base a lo anterior se analiza la eventual responsabilidad penal de la víctima en las hipótesis del delito de tráfico de drogas en cuanto se examina un caso hipotético basado en casos extraídos de la jurisprudencia junto con sus respectivas variantes. Por lo tanto, en el desarrollo de la investigación se permite estudiar el caso hipotético con sus respectivas variantes para establecer el juicio de responsabilidad penal de la víctima, en particular, verificando si alguno de los medios comisivos utilizados en contra ella en el contexto de la trata tienen incidencia o no en el iter criminis del delito de tráfico de drogas.

Memoria para optar al grado de Licenciado en Ciencias Jurídicas y Sociales

Le nettoyage des surfaces métalliques est nécessaire dans différents domaines de l'industrie moderne. L'industrie nucléaire cherche de nouvelles méthodes de décontamination des surfaces oxydées, et les installations thermonucléaires nécessitent le nettoyage des composants face au plasma pour enlever la couche déposée contenant tritium. L'ablation laser est proposée comme une méthode efficace et sûre pour le nettoyage des surfaces métalliques et leur décontamination. Le facteur important influençant le chauffage et l'ablation laser est la distribution en profondeur de l’intensité laser. Le modèle de propagation de la lumière dans une couche diffusant sur un substrat métallique est développé et appliqué pour analyser les caractéristiques de distribution de lumière. Pour simuler les surfaces contaminées, l'inox AISI 304L a été oxydé par laser et chauffé dans un four. La contamination radioactive de la couche d'oxyde a été simulée par l'introduction d’europium et / ou de sodium. Un facteur de décontamination de plus de 300 a été démontré avec le régime de nettoyage optimal trouvé. Une diminution de la résistance à la corrosion a aussi été montrée après un nettoyage laser. Les seuils d'ablation des surfaces ITER-like (représentatives d’ITER) ont été mesurés. Une vitesse de nettoyage de 0,07 m2/W∙h a été trouvée. Pour les surfaces miroir, les seuils de dommages étaient déterminés pour éviter les dommages lors du nettoyage au laser. La possibilité de restaurer la réflectivité après le dépôt d’une couche mince de carbone a été démontrée. Les perspectives de développement ultérieur de nettoyage laser sont discutées. / Metal surface cleaning is highly required in different fields of modern industry. Nuclear industry seeks for new methods for oxidized surface decontamination, and thermonuclear installations require the cleaning of plasma facing components from tritium-containing deposited layer. The laser ablation is proposed as an effective and safe method for metal surface cleaning and decontamination. The important factor influencing the laser heating and ablation is the in-depth distribution of laser radiation. The model of light propagation in a scattering layer on a metal substrate is developed and applied to analyse the features of light distribution. To simulate the contaminated surfaces, the stainless steel AISI 304L was oxidized by laser and in a furnace. Radioactive contamination of the oxide layer was simulated by introducing europium and/or sodium. The decontamination factor of more than 300 was demonstrated with found optimal cleaning regime. The decreasing of the corrosion resistance was found after laser cleaning. The ablation thresholds of ITER-like surfaces were measured. The cleaning productivity of 0.07 m2/hour∙W was found. For mirror surfaces, the damage thresholds were determined to avoid damage during laser cleaning. The possibility to restore reflectivity after thin carbon layer deposition was demonstrated. The perspectives of further development of laser cleaning are discussed.