An investigation of the sympathetic cooling method for the studies of large ultra-cold molecular ions in a quadrupole ion trap has been conducted.Molecular dynamics simulations are performed to study the rf heating mechanisms in the ion trap. The dependence of rf heating rates on the ion temperature, trapping parameters, and the number of ions is obtained. New rf heating mechanism affecting ultra-cold ion clouds exposed to laser radiation is described.The saturation spectroscopy setup of the hyperfine spectra of the molecular iodine has been built to provide an accurate frequency reference for the laser wavelength. This reference is used to obtain the fluorescence lineshapes of the laser cooled Mg$^+$ ions under different trapping conditions.The ion temperatures are deduced from the measurements, and the influence of the rf heating rates on the fluorescence lineshapes is also discussed. Cooling of the heavy ($m=720$a.u.) fullerene ions to under 10K by the means of the sympathetic cooling by the Mg$^+$ ions($m=24$a.u.) is demonstrated. The single-photon imaging system has been developed and used to obtain the images of the Mg$^+$ ion crystal structures at mK temperatures.

No description available.

Fusion reactors need methods to couple externalpower to confined plasmas. Ion cyclotron resonance heating(ICRH) is a method to radiate electromagnetic waves to couplepower to the kinetic motion of gyrating ions in a plasma. In thisreport we study ICRH with regard to the dispersive effects ofthe confined plasma in the JET tokamak. We study this witha division of the electric field with regard to toroidal modenumbers. Specifically we examine where dispersive effects arelocated in the plasma and if they have any importance. We alsostudy the ion-ion hybrid layer, where according to the dispersionrelation a singularity can occur. To do the analysis, we use thecode FEMIC to simulate fusion scenarios.The results show that ion absorption is stronger and morelocalized for low toroidal mode numbers. This is true for toroidalmode numbers n 10, and for n < 6 the resolution ofthe solutions does not suffice for a meaningful analysis. Anexamination of the effects of the singularity in the dispersionrelation at the ion-ion hybrid layer shows that the amount ofabsorbed power in the ion-ion hybrid layer is significantly smallerthan for the central region of absorption. This means that thesingularity does not affect ICRH heating in our scenarios in anymajor sense. / Fusionsreaktorer behöver metoder för attöverföra extern effekt till ett inneslutet plasma. Joncycklotronresonansuppvärmning (ICRH) är en uppvärmningsmetod därman strålar elektromagnetiska vågor in i ett plasma, vars effektöverförs till roterande joner. I denna rapport studerar vi ICRHmed avseende på de dispersiva effekterna i ett inneslutet plasma itokamaken JET. Detta undersöks med en uppdelning av det totalaelektriska fältet med avseende på toroidala moder. Vi undersökerspecifikt var i plasmat de dispersiva effekterna uppstår ochanalyserar deras påverkan på effektöverföringen. Vi studeraräven en singularitet som uppstår i dispersionsrelationen vid jonjon-hybridlagret. För att göra en analys används koden FEMICför att simulera ICRH-scenarion.Resultaten visar att jonernas absorption är starkare och merlokaliserad för låga toroidala modtal. Detta är sant för modtaln 10. För n < 6 är lösningarnas upplösning för dålig fören betydelsefull analys. En undersökning av jon-jon-hybridlagretvisar att mängden absorberad effekt inom detta område är avsevärt mindre än för de centrala områdena för absorption. Dettamedför att singulariteten i dispersionsrelationen inte påverkarICRH-uppvärmningen i våra simuleringar till en betydelsefullgrad. / Kandidatexjobb i elektroteknik 2021, KTH, Stockholm

<p>Lyophilization is the process of controllably removing the water content from a material with the objective of increasing its stability and, hence, its shelf life. This dissertation addresses two of the challenges faced by lyophilization, namely continuous temperature-monitoring and lengthy primary drying step.</p> <p>Continuous temperature monitoring of the product is imperative to a successful lyophilization process. It is more efficient to employ wireless temperature sensors rather than the conventional thermocouples. These wireless sensors need to keep a low profile that does not allow bulky battery attachment. Therefore, harvesting microwave energy is an excellent practice to power these sensors. Energy harvesting problem is twofold. One, designing an efficient flexible power-harvester (rectenna). To address this problem, we present a flexible rectenna with superior efficiency. While doing so, we establish the design procedure that can be followed for similar designs. Two, delivering sufficient power to the rectenna location inside the chamber. To address this problem, we propose two electromagnetic techniques, namely the statistical electromagnetics (SEM) and the electromagnetic time reversal (EMTR). These enable uniform power distribution and higher total efficiency.</p> As for the lengthy primary drying, to speed up the process, we propose RF-heating as a replacement for conventional heating. We establish a procedure for frequency selection based on the material under lyophilization and the geometrical properties of the freeze-drier’s chamber. The same techniques, SEM and EMTR are used. We conduct RF-assisted lyophilization processes based on SEM on different pharmaceutical bare excipients and on Myoglobin in four different excipients. The results confirm the superiority of the proposed technique in terms of drying time and heating uniformity.

<p>NR 20140805</p>

No description available.

This thesis concerns modelling of Coulomb collisions in toroidal plasma with Monte Carlo operators, which is important for many applications such as heating, current drive and collisional transport in fusion plasmas. Collisions relax the distribution functions towards local isotropic ones and transfer power to the background species when they are perturbed e.g. by wave-particle interactions or injected beams. The evolution of the distribution function in phase space, due to the Coulomb scattering on background ions and electrons and the interaction with RF waves, can be obtained by solving a Fokker-Planck equation.The coupling between spatial and velocity coordinates in toroidal plasmas correlates the spatial diffusion with the pitch angle scattering by Coulomb collisions. In many applications the diffusion coefficients go to zero at the boundaries or in a part of the domain, which makes the SDE singular. To solve such SDEs or equivalent diffusion equations with Monte Carlo methods, we have proposed a new method, the hybrid method, as well as an adaptive method, which selects locally the faster method from the drift and diffusion coefficients. The proposed methods significantly reduce the computational efforts and improves the convergence. The radial diffusion changes rapidly when crossing the trapped-passing boundary creating a boundary layer. To solve this problem two methods are proposed. The first one is to use a non-standard drift term in the Monte Carlo equation. The second is to symmetrize the flux across the trapped passing boundary. Because of the coupling between the spatial and velocity coordinates drift terms associated with radial gradients in density, temperature and fraction of the trapped particles appear. In addition an extra drift term has been included to relax the density profile to a prescribed one. A simplified RF-operator in combination with the collision operator has been used to study the relaxation of a heated distribution function. Due to RF-heating the density of thermal ions is reduced by the formation of a high-energy tail in the distribution function. The Coulomb collisions tries to restore the density profile and thus generates an inward diffusion of thermal ions that results in a peaking of the total density profile of resonant ions. / <p>QC 20130415</p>

No description available.

QC 20100622

The objective of the proposed research is to design, implement, and characterize low-cost, lightweight front-end components and subsystems in the microwave domain through innovative packaging architectures for remote sensing applications. Particular emphasis is placed on system-on-package (SoP) solutions implemented in organic substrates as a low-cost alternative to conventional, expensive, rigid, and fragile radio- frequency substrates. To this end, the dielectric properties of organic substrates RT/duroid 5880, 6002 and 6202 are presented from 30 GHz to 70 GHz, covering most of the Ka and V radar bands, giving also a thorough insight on the uncertainty of the microstrip ring resonator method by means of the Monte Carlo uncertainty analysis. Additionally, an ultra-thin, high-power antenna-array technology, with transmit/ receive (T/R) functionality is introduced for mobile applications in the X band. Two lightweight SoP T/R array panels are presented in this work using novel technologies such as Silicon Germanium integrated circuits and microelectromechanical system switches on a hybrid organic package of liquid crystal polymer and RT/duroid 5880LZ. A maximum power of 47 dBm is achieved in a package with a thickness of 1.8 mm without the need of bulky thermal management devices. Finally, to address the thermal limitations of thin-film substrates of interest (liquid crystal polymer, RT/duroid 6002, alumina and Aluminum Nitride), a thermal assessment of microstrip structures is presented in the X band, along with the thermal characterization of the dielectric properties of RT/duroid 6002 from 20 C to 200 C and from 30 GHz to 70 GHz. Additional high-power, X-band technologies presented in this work include: a novel and compact topology for evanescent mode filters, and low-profile Wilkinson power dividers implemented on Aluminum Nitride using Tantalum Nitride thin-film resistors.