The Journal of Technological and Space Plasmas
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White Paper: When will fusion energy truly become a reality?
Get PDFThis paper provides up-to-date insights into fusion (thermonuclear) research, detailing ongoing projects and planned devices. The document also explores alternative sources of energy, offering a comprehensive overview of the current landscape. Additionally, notable comments and observations are provided to illuminate key aspects of the discussed topics. Stay informed as we delve into the latest advancements and initiatives in the dynamic 1eld of energy research
On the significance of the external circuit, Langmuir and Bohm criterion for the stability of plasma fireballs
Get PDFThis 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
Numerical studies of a layered lithium-boron target for laser-driven aneutronic fusion reactions
Get PDFThis 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 having mean energies between 2-10 MeV
Influence of process parameters including the confining magnetic field of a plasma beam source on the deposition of N‐doped hydrogenated carbon films
Get PDFElectrically conductive nitrogen‐doped hydrogenated carbon films (a‐C:H:N) were deposited using a nitrogenacetylene gas mixture by plasma‐assisted chemical vapor deposition (PACVD). A capacitively coupled plasma beam source was used for the depositions. The plasma is excited by a radio‐frequency (RF) discharge and confined by Helmholtz magnetic coils, resulting in an increase in plasma density. The ion energy, as well as the deposition rate, can be controlled by the choice of the size of the coupling electrode, i.e. the ratio of cathode-to‐anode area, the electric current at the Helmholtz magnet coils, the total gas pressure and the RF power. The interdependence of these process parameters on the ion energy and the deposition rate has been studied in detail in this work. Hardness and electrical resistivity were measured on the deposited a‐C:H:N films
Derivation of a simple engineering equation for the minimum voltage of inverted fireball onset
Get PDFThis 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
Measurement of inverted n-hexane fireball properties with a Multipole Resonance Probe
Get PDFIn this paper we present for the first time the measurement of inverted fireballs in a low-pressure Ar/n-hexane plasma by using a Multipole Resonance Probe. The basic plasma parameters such as electron density, electron temperature and Debye length as well as the particle collision frequency have been obtained for different experimental settings. These measurements show that inverted fireballs that are created in chemically active plasma offer advantageous properties regarding deposition techniques. Furthermore, the influence of the plasma parameters on grid bias and changes in neutral gas pressure has been studied within this work. It is observed that the plasma density within an inverted fireball configuration can be raised by more than an order of magnitude compared to the background plasma or without biasing the grid electrode, respectively
On fusion chain reactions in 11B targets for laser driven aneutronic fusion
Get PDFThe 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
Large magnetic fields and direct electric energy after P+B11 nuclear fusion measured at the Pulsotron-3 reactor
Get PDFThe measured results of two tests T3073 and T3074 performed in 28 August, 2020 are presented in this paper. Tests are conducted in the z-pinch type nuclear fusion reactor Pulsotron-3 with the target loaded with Hydrogen-Boron (H+B11) thermonuclear fuel. A group of Energy Recovery Coils (ERCs) were mounted to recover the electric energy directly from the plasma for the first time in the world and ERCs stored the energy in several large capacitors. During the test T3073 and T3074 the energy recovery capacitors recovered 22.59% and 17.74% of the injected energy at the target. A magnetic sensor MAG-4 consisting of inductor coils and dipoles were installed in Pulsotron-3 to measure the Time Of Flight (TOF) of the plasma and the magnetic field generated due to nuclear fusion. Magnetic fields more than 4 megateslas are obtained during the two tests. It is also observed that Pulsotron-3 with the target loaded with thermonuclear fuel generated 20-34 times larger peak magnetic fields and 12-18 times larger stabilized magnetic fields compare to the tests done using unloaded target (dummy loads). In this proposed technology Pulsotron-3 utilizes thermonuclear fuel to generate clean electric power without CO2 footprint and reduce the operational cost. This industrial approach is a promising solution that can reduce world emissions to zero in less than 8 years
Surface Treatment of Handmade Lokta Paper by Atmospheric Pressure Dielectric Barrier Discharge Using 50 Hz Line Frequency
No full textThe discharge was generated between two rectangular parallel-plate copper electrodes using a sinusoidal voltage of 12.8 kV (rms) of frequency 50 Hz and characterized using electrical and optical measurements. The effects of the discharge on the wicking property and weight loss of Lokta paper were studied respectively by the wicking test and gravimetric method. The estimated value of electron density and electron temperature in the discharge were 8.47×108 cm-3 and 1.29 eV. The results showed a significant improvement in water absorption ability and considerable weight loss (%) in Lokta paper after the plasma treatment
Sheaths and Double Layers with Instabilities
Get PDFThe properties of sheaths and associated potential structures and instabilities cover a broad field which even a review cannot cover everything. Thus, the focus will be on about a dozen examples, describe their observations and focus on the basic physical explanations for the effects, while further details are found in the references. Due to familiarity the review focuses mainly on the authors work but compared and referenced related work. The topics start with a high frequency oscillations near the electron plasma frequency. Low frequency instabilities also occur at the ion plasma frequency.The injection of ions into an electron-rich sheath widens the sheath and forms a double layer. Likewise, the injection of electrons into an ion rich sheath widens and establishes a double layer which occurs in free plasma injection into vacuum. The sheath widens and forms a double layer by ionization in an electron rich sheath. When particle fluxes in "fireballs" gets out of balance the double layer performs relaxation instabilities which has been studied extensively. Fireballs inside spherical electrodes create a new instability due to the transit time of trapped electrons. On cylindrical and spherical electrodes the electron rich sheath rotates in magnetized plasmas. Electrons rotate due to which excites electron drift waves with azimuthal eigenmodes. Conversely a permanent magnetic dipole has been used as a negative electrode. The impact of energetic ions produces secondary electron emission, forming a ring of plasma around the magnetic equator. Such "magnetrons" are subject to various instabilities. Finally, the current to a positively biased electrode in a uniformly magnetized plasma is unstable to relaxation oscillations, which shows an example of global effects. The sheath at the electrode raises the potential in the flux tube of the electrode thereby creating a radial sheath which moves unmagnetized ions radially. The ion motion creates a density perturbation which affects the electrode current. If the electrode draws large currents the current disruptions create large inductive voltages on the electrode, which again produce double layers. This phenomenon has been seen in reconnection currents. Many examples of sheath properties will be explained. Although the focus is on the physics some examples of applications will be suggested such as neutral gas heating and accelerating, sputtering of plasma magnetrons and rf oscillators