Utilisation of plasma centrifuges for life support systems on Mars

In this paper the possibility of utilising a plasma centrifuge for oxygen generation in outer space is discussed. It is proposed that a plasma centrifuge can not only create oxygen for human consumption very efficiently but is also able to produce useful by-products. Special emphasis is given to life support systems working in the atmosphere of Mars, where oxygen and carbon raw materials can be obtained directly from the atmosphere. The system under consideration in this work is a plasma centrifuge with axial circulation that contains a fully ionised plasma. Under these conditions the carbon dioxide from the Mars atmosphere will be entirely dissociated. Thus, the atomic oxygen and carbon can easily be separated

Characterization of high-gamma activity in electrocorticographic signals

INTRODUCTION: Electrocorticographic (ECoG) high-gamma activity (HGA) is a widely recognized and robust neural correlate of cognition and behavior. However, fundamental signal properties of HGA, such as the high-gamma frequency band or temporal dynamics of HGA, have never been systematically characterized. As a result, HGA estimators are often poorly adjusted, such that they miss valuable physiological information. METHODS: To address these issues, we conducted a thorough qualitative and quantitative characterization of HGA in ECoG signals. Our study is based on ECoG signals recorded from 18 epilepsy patients while performing motor control, listening, and visual perception tasks. In this study, we first categorize HGA into HGA types based on the cognitive/behavioral task. For each HGA type, we then systematically quantify three fundamental signal properties of HGA: the high-gamma frequency band, the HGA bandwidth, and the temporal dynamics of HGA. RESULTS: The high-gamma frequency band strongly varies across subjects and across cognitive/behavioral tasks. In addition, HGA time courses have lowpass character, with transients limited to 10 Hz. The task-related rise time and duration of these HGA time courses depend on the individual subject and cognitive/behavioral task. Task-related HGA amplitudes are comparable across the investigated tasks. DISCUSSION: This study is of high practical relevance because it provides a systematic basis for optimizing experiment design, ECoG acquisition and processing, and HGA estimation. Our results reveal previously unknown characteristics of HGA, the physiological principles of which need to be investigated in further studies

Characterization of High-Gamma Activity in Electrocorticographic Signals

IntroductionElectrocorticographic (ECoG) high-gamma activity (HGA) is a widely recognized and robust neural correlate of cognition and behavior. However, fundamental signal properties of HGA, such as the high-gamma frequency band or temporal dynamics of HGA, have never been systematically characterized. As a result, HGA estimators are often poorly adjusted, such that they miss valuable physiological information.MethodsTo address these issues, we conducted a thorough qualitative and quantitative characterization of HGA in ECoG signals. Our study is based on ECoG signals recorded from 18 epilepsy patients while performing motor control, listening, and visual perception tasks. In this study, we first categorize HGA into HGA types based on the cognitive/behavioral task. For each HGA type, we then systematically quantify three fundamental signal properties of HGA: the high-gamma frequency band, the HGA bandwidth, and the temporal dynamics of HGA.ResultsThe high-gamma frequency band strongly varies across subjects and across cognitive/behavioral tasks. In addition, HGA time courses have lowpass character, with transients limited to 10 Hz. The task-related rise time and duration of these HGA time courses depend on the individual subject and cognitive/behavioral task. Task-related HGA amplitudes are comparable across the investigated tasks.DiscussionThis study is of high practical relevance because it provides a systematic basis for optimizing experiment design, ECoG acquisition and processing, and HGA estimation. Our results reveal previously unknown characteristics of HGA, the physiological principles of which need to be investigated in further studies

On fusion chain reactions in 11B targets for laser driven aneutronic fusion

The work presented in this letter suggests that it is possible to enhance the yield in laser driven aneutronic fusion devices by fusion chain reactions. This mechanism will be described using the example of aneutronic fusion between an incoming high-energy proton beam and a 11B target. Such fusion reactions create alphas that can again fuse with a 11B particle in a dense solid state target. An improved target design will be shown that enhances the recycling of fast alpha particles that are created from fusion reactions. It will also be argued that such alpha recycling may have already been observed in experiments, although it was attributed to another, more complex physical mechanism

On the significance of the external circuit, Langmuir and Bohm criterion for the stability of plasma fireballs

This paper is devoted to studying the influence of the external circuit as well as the Langmuir and Bohm criterion on the stability of plasma fireballs. A simple mathematical model is suggested that describes why plasma fireballs can get unstable up to the point where they start pulsating. The predictions of this model are compared to measured experimental data. Furthermore, it is argued that the Bohm criterion in particular determines whether a stable plasma fireball can be formed. This adds to the current understanding that fireballs are preliminarily formed due to a change in the space charge in front of a positively biased electrode in surrounding plasma. It is argued that the space charge distribution near the vicinity of the anode surface might play a role but that the initial stages of fireball formation are dominantly driven by the requirement of the double layer to satisfy Bohm’s sheath criterion and Langmuir’s criterion. The same holds for a collapsing fireball. This paper shows that if the Langmuir and the Bohm criterion are not satisfied simultaneously, a fireball cannot reach a stable state and will start pulsating with a frequency that is proportional to the square root of the mass of the working gas ions

Letter from the editor for the first issue of JTSP

oai:jtsp.eu:article/2

Derivation of a simple engineering equation for the minimum voltage of inverted fireball onset

This paper describes the derivation of a simple engineering equation to calculate the minimal necessary bias voltage for the onset of an inverted fireball. The calculation uses the electron density in the absence of an inverted fireball as well as the grid constant and the working gas species as input parameters. It will be shown that the interplay between ionsation potential, dissociation potential (for molecular working gases), as well as the electron density in the background plasma, play an important role in the necessary minimum bias on the fireball electrode. Some of the most common working gases and their relevant parameters will also be listed in this paper. This should give experimentalists and engineers a practical equation that can be used to quickly determine the most important electrical properties of the anode that is used to trap the inverted fireball. Thus, the planning and design of experimental setups or technological devices will be made much less time-consuming and, thus, more convenient

Temperature influence on the diethylamine sensing abilities of CuO nanoparticles deposited by atmospheric pressure plasma

In this work we present a copper oxide nanostructured analysed as a gas sensor but the focus of the paper is on the temperature dependance of the sensor sensing properties. As a case study temperature dependent diethylamine sensing is presented.The CuO nano flakes were deposited and evenly distributed on intercalated electrodes by an atmospheric pressure plasma source. The sensor was electrically connected to ohmmetre and inserted in an oven chamber where it was isolated from atmosphere and heated to desired tempearuteres. The intrinsic resistnace of the sensor was measured in dependence of the temperature and the temperature change rate. Then the possibility to detect diethylamine was investigated and the sensor response studied. Finally, the temperature dependence of the detection of the amine was explored. It was possible to demonstrate reliable sensing of the amine down to temperatures of 100 °C and below

Numerical studies of a layered lithium-boron target for laser-driven aneutronic fusion reactions

This paper explores a novel target design for laser-driven, aneutronic, proton-boron and proton-lithium fusion reactions consisting of a stack of boron and lithium foils. In contrast to a homogeneous target, this multi-layer setup provides additional fusion channels in the different materials. The composition of the layers is chosen in descending order of the fusion reactions\u27 thresholds, facilitating the fusion of protons that penetrate further into the material despite their energy losses due to electronic and nuclear stopping power. We employ a combination of Fluka simulations and additional numerical computations to evaluate thousands of target configurations. Four different beam energy distributions are considered: two Gaussian distributions with 6~MeV and 10~MeV mean energies, respectively, a Maxwell-Boltzmann distribution and a power law distribution. We explore the production of energy in a range of layer thicknesses motivated by the proton ranges based on ionization losses. The configuration which maximizes the produced energy for each beam type is reported. The production of fusion energy ranges from hundreds to thousands of millijoules for proton bunches of $10^{15}$ having mean energies between 2-10 MeV

Letter: Influence of inhomogeneous electrode biasing on the plasma parameters of inverted H2 fireballs

In this letter we present measurements of the influence on inhomogeneous electrode biasing on the basic plasma parameters of inverted fireballs in a hydrogen plasma. The measurements were performed in hydrogen because it is often used in many reactive plasmas, which are very important for technical or industrial applications. The dependence of the plasma parameters on voltages and currents on the electrodes are described in this work. It will be shown that the density profiles and the plasma potentials inside an inverted fireball can be shaped to a certain extend by asymmetric potentials on the anode