This thesis analyses the effect spin-orbit coupling has on the dispersion of Langmuir waves in magnetized plasmas, using recently developed kinetic theories of plasmas including quantummechanical and relativistic effects. Two new wave modes appearclose to the resonance <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?%5CDelta%20%5Comega_%7Bc%7D" /> = ( g/2 − 1)<img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?%5Comega_%7Bc%7D" /> , where <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?%5Comega_%7Bc%7D" /> is the cyclotron frequency and g is the electron gyromagnetic ratio. Forconsidered long wave lengths the deviation from this resonanceis very small. The wave modes are also very weakly damped.

Many astrophysical plasmas and some laboratory plasmas are relativistic: either the thermal speed or the local bulk flow in some frame approaches the speed of light. Often, such plasmas are magnetized in the sense that the Larmor radius is smaller than any gradient scale length of interest. Conventionally, relativistic MHD is employed to treat relativistic, magnetized plasmas; however, MHD requires the collision time to be shorter than any other time scale in the system. Thus, MHD employs the thermodynamic equilibrium form of the stress tensor, neglecting pressure anisotropy and heat flow parallel to the magnetic field. We re-examine the closure question and find a more complete theory, which yields a more physical and self-consistent closure. Beginning with exact moments of the kinetic equation, we derive a closed set of Lorentz-covariant fluid equations for a magnetized plasma allowing for pressure and heat flow anisotropy. Basic predictions of the model, including its thermodynamics and the dispersion relation's dependence upon relativistic temperature, are examined. Further, the model is applied to two extant astrophysical problems. / text

A three-beam heterodyne polarimeter has been designed and constructed to measure line-integrated density and Faraday rotation of accelerated spheromak plasmas in the Plasma Injector 1 and 2 devices (PI-1, PI-2) at General Fusion Inc. Faraday rotation is a function of the local magnetic field and electron density. Therefore, the polarimeter has the potential to provide information on the internal magnetic field of the plasma. A typical spheromak is about 1m in length and is accelerated to speeds on the order of 100km/s. At a bandwidth of 1MHz, the polarimeter can axially resolve the spheromak down to about 10cm. The polarimeter uses a $\nit{CO}_2$ laser that produces a Faraday rotation signal of about $0.5\degrees$ for a typical plasma with density and magnetic field on the order of $\ee{21}\mmt$ and 1T. The Faraday rotation measurement noise floor for a null signal is about $0.1\degrees$. Two important sources of Faraday rotation error are the ellipticity and collinearity of the plasma-immersed beams. These error sources are examined by sending the plasma beams through a rotating optic to mimic the path through a dense, magnetized plasma. The error due to the ellipticity effect has been reduced to below the noise floor by careful alignment and use of zero phase reflectors that minimize elliptical polarization of the beams. Collinearity error has been greatly improved by aligning the beams with a rotating ZnSe wedge. Measurements after the alignment match well with a model Faraday rotation signal generated from magnetic probe measurements. However, beam collinearity continues to be a significant source of error. For regions with strong density gradients, the size of this error can be on the order of the signal magnitude. For future work, steps should be taken to improve the alignment of the two plasma-immersed beams, and to shorten the length of the beam path to further reduce the beam collinearity error. / Thesis (Ph.D, Physics, Engineering Physics and Astronomy) -- Queen's University, 2014-04-30 22:17:18.648

Typical microwave components such as antennas are large in size and occupy considerable space. Since multiple standards are utilized in modern day systems and thus multiple antennas are required, it is best if a single component can be reconfigured or tuned to various bands. Similarly phase shifters to provide beam scanning and polarization reconfigurable antennas are important for modern day congested wireless systems. Tunability of antennas or phase shifting between antenna elements has been demonstrated using various techniques which include magnetically tunable components on ferrite based substrates. Although this method has shown promising results it also has several issues due to the use of large external electromagnets and operation in the magnetically saturated state. These issues include the device being bulky, inefficient, non-integrable and expensive. In this thesis, we have tried to resolve the above mentioned issues of large size and large power requirement by replacing the large electromagnets with embedded bias windings and also by operating the ferrites in the partially magnetized state. New theoretical models and simulation methodology have been used to evaluate the performance of the microwave passive components in the partially magnetized state. A multilayer ferrite Low Temperature Cofired Ceramic (LTCC) tape system has been used to verify the performance experimentally. There exists a good agreement between the theoretical, simulation and measurement results. Tunable antennas with tuning range of almost 10 % and phase shifter with an FoM of 83.2/dB have been demonstrated in this work, however the major contribution is that this has been achieved with bias fields that are 90 % less than the typically reported values in the literature. Finally, polarization reconfigurability has also been demonstrated for a circular patch antenna using a low cost additive manufacturing technique. The results are promising and indicate that highly integrated ferrite based tunable components are feasible in small form factor, without the need of the large electromagnets and coils, and thus can be operated at very low bias levels as compared to the ones which are operated in the saturated state with external bias mechanisms.

京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第19487号 / 理博第4147号 / 新制||理||1596(附属図書館) / 32523 / 京都大学大学院理学研究科物理学・宇宙物理学専攻 / (主査)教授 青山 秀明, 教授 田中 貴浩, 教授 畑 浩之 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DFAM

Relaxation mechanisms in perpendicularly-magnetized ultrathin Fe/ 2 ML Ni(111)/ W(110) films, with thickness between 1.25 and 2.00 ML, have been studied using the ac magnetic susceptibility as a function of temperature and/or time. Different time scales were probed by varying the constant rate of temperature variation, R as the susceptibility was measured. After quenching the film from high temperature, the susceptibility curve was found to relax through a shift in the peak position along the temperature axis and through changes in shape, as a function of time. In general, two opposing behaviors were found; for small R (≤0.30 K/s) the susceptibility peak temperature decreases as R increases, for large R (≥ 0.30 K/s) the peak temperature increases with R. The first behavior is understood as a "dynamical observation" of a domain phase transformation. The density of topological defects in the quenched high temperature delocalized phase undergoes an activated relaxation as low temperature ordered stripe phase is established. The fundamental time scale (𝜏_0R) of this process is in the order of 1.0 s. These findings complement the results of numerical simulation [24, 26, 27] and quantify the important dynamical barriers involved in the geometrical rearrangement of domains in moving from a delocalized phase to the ordered stripe phase. The experiments at large R are sensitive to a much shorter time scale over which the domain density equilibrates when temperature is changed. This process causes an increase in the peak temperature with R that depends linearly on R over the range of values of R accessible in this study. / Thesis / Doctor of Philosophy (PhD)

Experiments in high energy density (HED) plasma physics have become more accessible with the increasing availability of high-intensity pulsed lasers. Extending the experiment parameters to include magnetized HED plasmas requires a field source that can generate fields of order 100 tesla. This dissertation discusses the design and implementation of a pulsed field driver with a designed maximum of 2.2 MA from a 160 kJ capacitor bank. Faraday rotation measurement of 63 T for a 1.0 MA discharge supported Biot-Savart estimates for a single-turn coil with a 1 cm bore. After modification, the field driver generated up to 15 T to magnetize supernova-like spherical blast waves driven by the Texas Petawatt Laser. The presence of the high field suppressed blast wave expansion, and had the additional effect of revealing a cylindrical plasma along the laser axis. / text

<p>Thin films of metals and compounds have a very wide range of applications today. Many of the deposition methods used for the production of such films utilize plasma to support the growth the film, e.g. by the supply of energy and the enhancement of reactivity. This thesis focuses on the physical vapor deposition (PVD) of thin films by high density plasma sources based on hollow cathodes and aims to increase the understanding of the deposition process and its influence on the film properties.</p><p>Titanium nitride films reactively deposited by the low-pressure hybrid plasma (HYP LP) source exhibited excellent properties and was deposited at considerable higher rates than films deposited by conventional methods.</p><p>An original finding in this work is the influence of substrate material on the deposition process and consequently on the properties of the deposited film. In the deposition of TiN films by the HYP LP source it was found that the substrate temperature was higher for Si substrates than for steel substrates due to a more efficient absorption of microwave power in Si than in steel. Further, it was found that ferromagnetic substrates influence the film growth in magnetized plasma systems. An effect of the ferromagnetic substrates is the enhancement of ion bombardment that increases the growth temperature and affects the texture and morphology of the growing films. It was also found that a DC bias can change the TiN film properties considerably and compensate the effect of ferromagnetic substrates.</p><p>High rate depositions of chromium and chromium nitride films by the RF hollow cathode plasma jet (RHCPJ) source were studied. The performance of the reactive diffuse arc process and the CrN film properties indicates that the process can be transferred from small cylindrical cathodes to linear magnetized hollow cathodes which allow deposition on considerable larger areas and this is important for industrial applications.</p>

Thin films of metals and compounds have a very wide range of applications today. Many of the deposition methods used for the production of such films utilize plasma to support the growth the film, e.g. by the supply of energy and the enhancement of reactivity. This thesis focuses on the physical vapor deposition (PVD) of thin films by high density plasma sources based on hollow cathodes and aims to increase the understanding of the deposition process and its influence on the film properties. Titanium nitride films reactively deposited by the low-pressure hybrid plasma (HYP LP) source exhibited excellent properties and was deposited at considerable higher rates than films deposited by conventional methods. An original finding in this work is the influence of substrate material on the deposition process and consequently on the properties of the deposited film. In the deposition of TiN films by the HYP LP source it was found that the substrate temperature was higher for Si substrates than for steel substrates due to a more efficient absorption of microwave power in Si than in steel. Further, it was found that ferromagnetic substrates influence the film growth in magnetized plasma systems. An effect of the ferromagnetic substrates is the enhancement of ion bombardment that increases the growth temperature and affects the texture and morphology of the growing films. It was also found that a DC bias can change the TiN film properties considerably and compensate the effect of ferromagnetic substrates. High rate depositions of chromium and chromium nitride films by the RF hollow cathode plasma jet (RHCPJ) source were studied. The performance of the reactive diffuse arc process and the CrN film properties indicates that the process can be transferred from small cylindrical cathodes to linear magnetized hollow cathodes which allow deposition on considerable larger areas and this is important for industrial applications.

A code that solves the coupled electron drift kinetic and temperature equations has been written to study the effects of collisionality and particle trapping on temperature equilibration along magnetic field lines. A Chapman-Enskog-like approach is adopted with the time-dependent distribution function written as the sum of a dynamic Maxwellian and a kinetic distortion expanded in Legendre polynomials. The drift kinetic equation is solved on a discrete grid in normalized speed, and an FFT algorithm is used to treat the onedimensional spatial domain along the magnetic field. The dependence of the steady-state temperature on collisionality and magnetic well depths is discussed in detail. As collisionality decreases (increasing background temperature), temperature variations decrease. As magnetic well depth increases (at fixed collisionality), temperature variations along the field line increase.