35 research outputs found
Image Registration with Particles, Examplified with the Complex Plasma Laboratory PK-4 on Board the International Space Station
No full textOften, in complex plasmas and beyond, images of particles are recorded with a side-by-side camera setup. These images ideally need to be joined to create a large combined image. This is, for instance, the case in the PK-4 Laboratory on board the International Space Station (the next generation of complex plasma laboratories in space). It enables observations of microparticles embedded in an elongated low temperature DC plasma tube. The microparticles acquire charges from the surrounding plasma and interact strongly with each other. A sheet of laser light illuminates the microparticles, and two cameras record the motion of the microparticles inside this laser sheet. The fields of view of these cameras slightly overlap. In this article, we present two methods to combine the associated image pairs into one image, namely the SimpleElastix toolkit based on comparing the mutual information and a method based on detecting the particle positions. We found that the method based on particle positions performs slightly better than that based on the mutual information, and conclude with recommendations for other researchers wanting to solve a related problem
Influence of Reduced Soot Emission and Increased Water Vapor Content on Contrail Climate Impact
No full textContrails have a significant impact on climate and contribute to global warming. Their formation is primarily caused by the emission of water vapor and soot particles from aircraft engines. When water vapor is released into the cold and humid upper atmosphere, it can rapidly condensate on soot particles and form ice crystals.
Reducing carbon and soot emissions from aviation is critical in mitigating the climate impact of air travel. Hydrogen presents a compelling alternative to traditional jet fuels; it emits no carbon when burned in an engine, although it does produce more water vapor, which could intensify contrail formation.
In our study, we explore the effect of reducing soot emissions and increasing water vapor in the engine exhaust as a first step towards using hydrogen as fuel. The Contrail Cirrus Prediction (CoCiP) model was used to simulate contrail properties and estimate their climate impact.
We focus on Europe with air traffic data from Eurocontrol for the entire year 2019. Specific aircraft data were obtained from the BADA3 database, soot emissions stem from a state-of-the-art method to scale ICAO emissions to cruise conditions and weather data from ECMWF-IFS forecast.
For our investigations we reduce the engine soot emissions for kerosene by up to 99% for the complete fleet. Then for each flight and aircraft, we calculate the optical thickness and radiative forcing from contrails in Europe in 2019 based on ECMWF weather information and quantify the relative changes for a stepwise reduction in soot emissions of the fleet. In a second step we increase the water vapor emissions in relation to the expected change for future hydrogen combustion. Results from the simulations are presented and the potential impact for future novel engine technologies and fuels are discussed
The journey from newly qualified to a professional opera singer
No full textIn my work I process my development of vocal technique and how it was affecting me during my artistic project "My home - a way back" with director Mira Bartov. During the training, I have met different coaches and singing teachers who have meant a lot for me to find my vocal identity. I discuss and analyze in this work from my process diary, which has been continuously during the work and the methods (sound recording and video filming) come to the tools I use to develop in the best way.
My intention with this work has been that in the future I will be able to use this work and the different types of documentation, which I have used both in the singing room so that on stage. I pay attention to my strengths and weaknesses and educators help adapt the vocal technique exercises and mental settings for these properties to be processed adequately.
I have chosen to refer to the book: The inner voice - The Making of a Singer by Renée Fleming which I have found similarities with myself in the description she has in her book both on a vocally and musically plan. The choice to use this book as a starting point to the work has been that it puts into words a lot of my experiences and approaches that I can relate to. This book has been formulated in a way that others can partake observations and tips author writes about.
In this work, we read about how different teachers approaching my musicality and largely focus and ultimate goal of my project above. The bulk of this work has focused on finding the natural sound that is the basis for vocal identity. Thereby, my work is about my individual process and is not an analytical, problem-work
Interaction of particles with complex electrostatic structures and 3D clusters
No full textParticles of micrometer size externally introduced in plasmas usually find their positions of levitation in the plasma sheath, where the gravity force is compensated by the strong electric field. Here due to electrostatic interaction they form different structures, which are interesting objects for the investigation of strongly coupled systems and critical phenomena. Because of the low
damping (e.g. in comparison to colloidal suspension) it is possible to measure the dynamics up to the relevant highest frequency (e.g. Einstein frequency) at the most elementary level of single particle motion. The task of this work was to analyze the three dimensional structure, dynamical processes and the limit of the cooperative behavior in small plasma crystals. In addition to the
study of the systems formed, the immersed particles themselves may be used for diagnostics of the plasma environment: estimation of parameters or monitoring of the processes inside plasma. The laboratory experiments are performed in two radio-frequency (RF) plasma reactors with
parallel plate electrodes, where the lower electrode is a so-called "adaptive electrode". This electrode is segmented into 57 small "pixels" independently driven in DC (direct current) and/or RF voltage. When RF voltage is applied to one of these pixels, a bright localized glow, "secondary
plasma ball", appears above. Three dimensional dust crystals with less than 100 particles are formed inside this "plasma ball" - the ideal conditions for the investigation of the transition from cluster systems to collective systems. The investigation of the particle interactions in crystals is performed with an optical diagnostic, which allows determination of all three particle coordinates simultaneously with time resolution of 0.04 sec.
The experimental results are:
1. The binary interaction among particles in addition to the repelling Coulomb force exhibits also an attractive part, which is experimentally determined for the first time.
2. Analysis of the dynamical evolution shows the tendency of the systems to approach the state with minimum energy by rearranging particles inside.
3. The measured 63 particles' crystal vibrations are in close agreement with vibrations of a drop with surface tension. This indicates that even a 63 particle crystal already exhibits properties normally associated with the cooperative regime.
The possibility to use levitated particles as a new powerful diagnostic of the plasma sheath region is proposed. The existence of different equilibrium positions of microparticles suspended in an Oxygen discharge provides evidence of a structured electronegative plasma sheath, a feature so far only mathematically and numerically investigated
Brownian-like motion of a single dust grain in a radio-frequency plasma discharge comparison of experiments and simulations
No full textBronwnian-like motion of a single dust-grain in a radio frequency plasma has been studied by
different research groups. The rise of the particles temperature above “room temperature” is
attributed to e.g. random fluctuations of the particle charge and fluctuations of the electrical
field. Additional disturbance might occur due to gas density variations, temporal variation of
the particles mass and particle interaction with the illuminating laser light. In addition, a nonoptimal frame rate of the optical diagnostic system and pixel locking can lead to an incorrect
estimation of the particle kinetic temperature.
Our experiments are conducted in a weakly ionized radio-frequency gas discharge at a low
neutral gas pressure and power. A single micron sized spherical particle is trapped in a
harmonic-like potential trap in the sheath of the lower driven electrode [1]. Its twodimensional planar motion is recorded with a long-distance microscope and a high-resolution
camera. From the measured particle positions we derive the probability density function, the
velocity autocorrelation function and the mean squared displacement.
We obtain a particle kinetic temperature above 350 K, a neutral gas damping time of about
0.5 sec and a resonance frequency of 1-2 Hz. Anisotropic oscillation of the particle occurs,
leading to angle dependent temperatures along the x and y direction in the plane of the
recorded images, which can be explained by the presence of an asymmetric horizontal
potential trap.
Experimental observations are compared with our simulations using md simulations and the
Ornstein-Uhlenbeck stochastic process
Crystallization in three-dimensional complex plasmas
No full textComplex plasmas are low-temperature plasmas in which microparticles are embedded. The microparticles are illuminated with a laser sheet, and their movement is traced in time and space using high speed digital cameras. This allows studying their dynamics on the most basic level, that of the individual particles. Moving the laser sheet through the system makes three-dimensional investigations possible by recording several slices in succession in a tomographic procedure.
The microparticles in the plasma get strongly charged by collecting unequal amounts of ions and electrons from the surrounding plasma. They acquire mean charges of several thousands of electrons. Thus, they strongly interact with each other. When the interaction strength is much larger than the microparticles' kinetic temperature, the microparticles arrange in ordered structures, and a 'plasma crystal' forms. Under gravity conditions, these crystals are stressed by the strong forces required to counteract gravity, and plasma-specific instabilities easily induce melting. Under microgravity, however, the microparticles are suspended in the bulk of the plasma, where the ion fluxes are small, and the fluid-solid phase transition is realized via a generic mechanism that is common to a wide range of materials.
Here, we give an overview over crystallization experiments in complex plasmas with an emphasis on data recorded with the PK-3 Plus Laboratory that was hosted on board the International Space Station until 2013. This laboratory was very versatile, but its main goal was to study crystallization, with 32 experiments dedicated to this topic. Crystallization or melting were typically induced by changing the neutral gas pressure, but could also be caused by changes in the particles charges, or, in the case of melting, by shaking a plasma crystal with an electric field.
This last method was applied to induce crystallization fronts by melting a preformed plasma crystal incompletely and studying the recrystallization process. We study the three- dimensional propagation of these crystallization fronts: By performing repeated short scans through the system, we find the three-dimensional position of the fronts and determine their propagation velocity. We use both conventional analysis of the microparticle dynamics and novel techniques developed by C. Dietz et al. to accurately identify the crystalline and fluid regions
