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arXiv2008

Attainment of Gigavolt Potentials by Fluid Dynamic Suppression of the Stepped Leader its Significance for Thermonuclear Ignition

It is proposed to levitate a conducting sphere in a high pressure Taylor flow and to charge it up to gigavolt potentials, either mechanically as in a Van de Graaff electrostatic generator, or inductively by a rising magnetic field. If the Taylor flow is sufficiently fast, it should overcome the electric pressure and breakdown by stepped leader formation, leading to the maximum attainable voltage by the Paschen law. Discharging the electrostatically stored energy can be done by controlled breakdown. With gigajoule energies stored and released in about 10^-8 sec, this implies and electric pulse power of the order 10^17 Watt, opening the prospect of large driver energies for thermonuclear ignition.

physics.acc-ph↗
arXiv2011

Comment on ``Rotation Velocities and Radial Electric Field in the Plasma Edge''

The calculation presented in "Rotation Velocities and Radial Electric Field in the Plasma Edge" by W. M. Stacey [Contrib. Plasma Phys. 46, (2006)] contains an inconsistent treatment of the electrostatic potential. Comparing the expressions for the potential associated with the radial electrostatic field with that associated with the poloidal electrostatic field reveals the inconsistency. A field-theoretic perspective implies that the electrostatic field must vanish in a model based upon the physics of a neutral, conducting fluid.

physics.plasm-ph↗
arXiv2008

A Gear-like Predictor-Corrector method for Brownian Dynamics Simulation

We introduce a Predictor-Corrector type method suitable for performing many-particle Brownian Dynamics simulations. Since the method goes over to the Gear's method for Molecular Dynamics simulation in the limit of vanishing friction, we refer to it as a Gear-like algorithm. The algorithm has been tested on a one-dimensional, stochastically damped harmonic oscillator model, showing that it can cover a wide range of friction coefficients with a high-order accuracy, excellent stability, and a very small energy drift on the long time scales.

physics.plasm-ph↗
arXiv2008

On the application of Maxwell's theory to many-body systems, or why the resistive magnetohydrodynamic equations are not closed

The resistive magnetohydrodynamic (MHD) equations as usually defined in the quasineutral approximation refer to a system of 14 scalar equations in 14 scalar variables, hence are determined to be complete and soluble. These equations are a combination of Navier-Stokes and a subset of Maxwell's. However, one of the vector equations is actually an identity when viewed from the potential formulation of electrodynamics, hence does not determine any degrees of freedom. Only by reinstating Gauss's law does the system of equations become closed, allowing for the determination of both the current and mass flow velocity from the equations of motion. Results of a typical analysis of the proposed electromagnetic hydrodynamic model including the magnetization force are presented.

physics.plasm-ph↗
arXiv2010

Effect of magnetization and magnetic field variation on stationary axisymmetric equilibrium

The inclusion of plasma magnetization in the equations of stationary equilibrium is derived, and its effect on the determination of axisymmetric equilibrium calculated. A factor of 2 on the pressure gradient arises in the equilibrium equation from the force felt by the dipole moment density. The algebraic and differential equation formulations are compared both with and without consideration of magnetization, revealing the effects of both magnetization and magnetic field variation on the equilibrium, which become more pronounced for high pressures in a weak external field. The equivalence of the magnetized equilibrium equation with the standard equilibrium equation in the limit of vanishing magnetization is demonstrated.

physics.plasm-ph↗
arXiv2008

Plasma Kinetics in Electrical Discharge in Mixture of Air, Water and Ethanol Vapors for Hydrogen Enriched Syngas Production

The complex theoretical and experimental investigation of plasma kinetics of the electric discharge in the mixture of air and ethanol-water vapors is carried out. The discharge was burning in the cavity, formed by air jets pumping between electrodes, placed in aqueous ethanol solution. It is found out that the hydrogen yield from the discharge is maximal in the case when ethanol and water in the solution are in equal amounts. It is shown that the hydrogen production increases with the discharge power and reaches the saturation at high value. The concentrations of the main stable gas-phase components, measured experimentally and calculated numerically, agree well in the most cases.

physics.plasm-ph↗
arXiv2008

Ways towards pure deuterium inertial confinement fusion through the attainment of gigavolt potentials

The attainment of ultrahigh electric potentials by suppressing the stepped leader breakdown of a highly charged conductor levitated in a spiraling Taylor flow opens up the possibility of order of magnitude larger driver energies for the ignition of thermonuclear reactions by inertial confinement. In reaching gigavolt potentials, intense 1016 Watt, GeV ion beams become possible. Together with their large self-magnetic field, these beams should be powerful enough to launch a thermonuclear micro-detonation into pure deuterium, compressed and ignited by such beams. In high gain laser fusion the proton flash from the micro-explosion is likely to destroy the optical laser ignition apparatus, and it is not explained how to avoid this danger. The possible attainment of gigavolt potentials could make laser fusion obsolete.

physics.plasm-ph↗
arXiv2008

Comment on "Sizes and relative geoeffectiveness of interplanetary coronal mass ejections and the preceding shock sheaths during intense storms in 1996-2005" by J. Zhang et al

Recently Zhang et al. [2008] presented a statistical study of sizes and relative geoeffectiveness of ICMEs (bodies of magnetic clouds) and preceding sheaths for 46 events responsible for intense (Dst < -100 nT) geomagnetic storms in 1996-2005 in which only a single ICME was responsible for generating the storm. Here we would like to comment several results and conclusions of this paper.

physics.space-ph↗
arXiv2008

Oblique ion collection in the drift-approximation: how magnetized Mach-probes really work

The anisotropic fluid equations governing a frictionless obliquely-flowing plasma around an essentially arbitrarily shaped three-dimensional ion-absorbing object in a strong magnetic field are solved analytically in the quasi-neutral drift-approximation, neglecting parallel temperature gradients. The effects of transverse displacements traversing the magnetic presheath are also quantified. It is shown that the parallel collection flux density dependence upon external Mach-number is $n_\infty c_s \exp[-1 -(M_{\parallel\infty}- M_\perp\cotθ)]$ where $θ$ is the angle (in the plane of field and drift velocity) of the object-surface to the magnetic-field and $M_{\parallel\infty}$ is the external parallel flow. The perpendicular drift, $\M_\perp$, appearing here consists of the external $\E\wedge\B$ drift plus a weighted sum of the ion and electron electron diamagnetic drifts that depends upon the total angle of the surface to the magnetic field. It is that somewhat counter-intuitive combination that an oblique (transverse) Mach probe experiment measures.

physics.plasm-ph↗
arXiv2008

Electromechanical Effect in Complex Plasmas

Experimental results on an auto-oscillatory pattern observed in a complex plasma are presented. The experiments are performed with an argon plasma which is produced under microgravity conditions using a capacitively-coupled rf discharge at low power and gas pressure. The observed intense wave activity in the complex plasma cloud correlates well with the low-frequency modulation of the discharge voltage and current and is initiated by periodic void contractions. Particle migrations forced by the waves are of long-range repulsive and attractive character.

physics.plasm-ph↗
arXiv2009

Sizing of Hall effect thrusters with input power and thrust level: An Empirical Approach

Sizing methods can be used to get a first estimate of the required Hall thruster dimensions and operating conditions for a given input power and a corresponding thrust level. After a review of the existing methods, a new approach, which considers the three characteristic thruster dimensions, i.e. the channel length, the channel width and the channel mean diameter as well as the magnetic field, is introduced. This approach is based on analytical laws deduced from the physical principles that govern the properties of a Hall effect thruster, relying on a list of simplifying assumptions. In addition, constraints on the channel wall temperature as well as on the propellant atom density inside the channel are taken into account. The validity of the scaling laws is discussed in light of a vast database that comprises 23 single-stage Hall effect thrusters covering a power range from 10 W to 50 kW. Finally, the sizing method is employed to obtain a preliminary geometry and the magnetic field strength for a 20 kW and a 25 kW Hall effect thruster able to deliver a thrust of 1 N, respectively 1.5 N.

physics.plasm-ph↗
arXiv2009

Efficient Raman amplification into the PetaWatt regime

Raman amplification of a short laser pulse off a long laser beam has been demonstrated successfully for moderate probe intensities ($\sim 10^{16}$ W/cm$^2$) and widths ($\sim 50$ micron). However, truly competitive intensities can only be reached if the amplification process is carried out at much higher probe intensities ($10^{17}-10^{18}$ W/cm$^2$ after amplification) and widths (1-10 mm). In this paper we examine the opportunities and challenges provided by this regime through the first 2-dimensional particle-in-cell simulations using wide pulses. A parameter window is identified in which a 10 TW, 600 $μ$m wide, 25 ps long laser pulse can be efficiently amplified to 2 PW peak intensity.

physics.plasm-ph↗
arXiv2008

Ignition of a deuterium micro-detonation with a gigavolt super marx generator

The Centurion-Halite experiment demonstrated the feasibility of igniting a deuterium-tritium micro-explosion with an energy of not more than a few megajoule, and the Mike test, the feasibility of a pure deuterium explosion with an energy of more than 10^6 megajoule. In both cases the ignition energy was supplied by a fission bomb explosive. While an energy of a few megajoule, to be released in the time required of less than 10^-9 sec, can be supplied by lasers and intense particle beams, this is not enough to ignite a pure deuterium explosion. Because the deuterium-tritium reaction depends on the availability of lithium, the non-fusion ignition of a pure deuterium fusion reaction would be highly desirable. It is shown that this goal can conceivably be reached with a "Super Marx Generator", where a large number of "ordinary" Marx generators charge (magnetically insulated) fast high voltage capacitors of a second stage Marx generator, called a "Super Marx Generator", ultimately reaching gigavolt potentials with an energy output of 100 megajoule. An intense 10^7 Ampere-GeV proton beam drawn from a "Super Marx Generator" can ignite a deuterium thermonuclear detonation wave in a compressed deuterium cylinder, where the strong magnetic field of the proton beam entraps the charged fusion reaction products inside the cylinder. In solving the stand-off problem, the stiffness of a GeV proton beam permits to place the deuterium target at a comparatively large distance from the wall of a cavity confining the deuterium micro-explosion.

physics.gen-ph↗
arXiv2008

Deuterium microbomb rocket propulsion

Large scale manned space flight within the solar system is still confronted with the solution of two problems: 1. A propulsion system to transport large payloads with short transit times between different planetary orbits. 2. A cost effective lifting of large payloads into earth orbit. For the solution of the first problem a deuterium fusion bomb propulsion system is proposed where a thermonuclear detonation wave is ignited in a small cylindrical assembly of deuterium with a gigavolt-multimegampere proton beam, drawn from the magnetically insulated spacecraft acting in the ultrahigh vacuum of space as a gigavolt capacitor. For the solution of the second problem, the ignition is done by argon ion lasers driven by high explosives, with the lasers destroyed in the fusion explosion and becoming part of the exhaust.

physics.gen-ph↗
arXiv2009

Statistical theory of structure formation: self-organization

We present the first prediction of the probability distribution function (PDF) for self-organization of shear flows modeled by a nonlinear diffusion equation with a stochastic forcing. A novel non-perturbative method based on a coherent structure is utilized for the prediction of the PDFs, revealing strong intermittency with exponential tails. Numerical simulations confirm these results. The predicted power spectra are also in a good agreement with simulation results. The results imply a significant probability of supercritical states due to stochastic perturbation in a variety of systems.

physics.flu-dyn↗
arXiv2009

Non-stationary magnetized axially symmetric equilibrium from the fluid equations of motion

The equations of motion for a fully ionized hydrogenic plasma in applied coaxial electric and magnetic fields are analyzed, where the term for the Hall effect in the generalized Ohm's law equation picks up a factor of 1/2 relative to its usual expression. Magnetization of the medium is incorporated through the decomposition of the Hall term and the inclusion of the magnetization force, which is found to equal or exceed the gradient of the scalar pressure. A limit on the kinetic pressure obtains which corresponds to the usual limit of unity for a certain selection of parameters. Solutions of these equations for the free motion of the charges in the case of an infinite column with azimuthal symmetry are compared for various prescribed pressure profiles, where one finds that the profile near the outer edge plays an important role in the feasibility of the equilibrium.

physics.plasm-ph↗
arXiv2009

Heavy Ion-Beam Driven Isentropic Compression Experiments

A new design for heavy-ion beam driven isentropic compression experiments is suggested and analysed. The proposed setup utilises long stopping ranges and the variable focal spot geometry of the high-energy uranium beams delivered at the GSI Helmholtzzentrum für Schwerionenforschung and Facility for Antiproton and Ion Research accelerator facilities in Darmstadt, Germany, to produce a planar ramp loading of various samples. In such experiments, the predicted high pressure amplitudes (\unit[$<10$]{Mbar}) and the predicted short timescales of compression (\unit[$<10$]{ns}) will allow testing the time dependent material deformation phenomena at unprecedented extreme conditions.

physics.plasm-ph↗