Flow Of Neutral Particles Research Articles

Ionized gas Thermoelectric Generator

The behavior of charged particles mixed with neutral particles laid in Circular Ratchet Potential (CRP) inside circular tube container was studied, showing a net Counter-clockwise flow of charged particles and other net flow of neutral particles equal in magnitude and opposite in direction (Clockwise), the neutral flow of particles will not cancel the positive particles flow; by Causality Principle. These two opposite flow of particles will reach terminal intensity at some stage inside the circular path; the charged particles are confined to move in a semi-circular (Nut Shape) trajectory according to the CRP, while the neutral particles can escape out of the container in tangential trajectory, hence producing perpetual disequilibrium in the thermodynamic properties of the system.Allowing the neutral particles to escape through outer tangential slots, and allow new neutral particles to enter the container through inner slots to compensate neutral particles. This gives the basic idea for a new concept of Brownian Motor (Plyukhin, 2013) [1] or Thermoelectric Generator (TEG) (Bqoor, 2013) [2], then the excess in charged particles flow will reduce the neutral particle flow and produce micro-turbulences. This mechanism will allow extracting power from the ambient thermal energy.Several considerations including efficiency, manufacturing and improvement aspects were evaluated and discussed in this paper. However, this Ionized Gas TEG can be assumed as a Perpetual Motion Machine (Rao, 2004) [3] of the second type, hence questioning the validity of the “empirical” Second Law of Thermodynamics, were several phenomena showing the necessity for new formula amending the Second Law of Thermodynamics (Crosignani and Di Porto, 2001; Wang et al., 2002) [4,5].

Увлечение электронов в полупроводниковой наноструктуре потоком нейтральных частиц

AbstractThe entrainment of current carriers (electrons) in a two-dimensional semiconductor nanostructure by a flow of neutral particles (atoms or molecules) moving near its surface is considered. It is shown that the physical mechanism is similar to the entrainment of electrons with an ion beam inquantum wires, considered earlier in the works of V.L. Gurevich and M.I. Muradov.

Entrainment of Electrons in a Semiconductor Nanostructure by a Flow of Neutral Particles

The entrainment of current carriers (electrons) in a two-dimensional semiconductor nanostructure by a flow of neutral particles (atoms or molecules) moving near its surface is considered. It is shown that the physical mechanism is similar to the entrainment of electrons with an ion beam inquantum wires, considered earlier in the works of V.L. Gurevich and M.I. Muradov.

Latest LHCf results and preparation to the LHC run for 13 TeV proton–proton interactions

The LHCf experiment is a CERN experiment dedicated to forward physics which is optimized to measure the neutral particle flow at extreme pseudo-rapidity val- ues, ranging from 8.4 up to infinity. LHCf results are extremely important for the cal- ibration of the hadronic interaction models used for the study of the development of atmospheric showers in the Earth atmosphere. Starting from the recent run of proton- Lead nucleus interactions at LHC, the LHCf and ATLAS collaborations have performed a common data taking which allows a combined study of the central and forward re- gions of the interaction. The latest results of LHCf, the upgrade of the detectors for the next 6.5 TeV + 6.5 TeV proton-proton run and the status of the LHCf-ATLAS common activities are summarized in this paper.

Free-molecule flow of neutral particles with density depleted by ionization

Free-molecule flow of neutral particles is considered in the kinetic approximation under conditions of strong ionization depletion. The problem is solved for an arbitrary semi-isotropic distribution function of particles by velocities at the surface of the emitter. The kinetic effects of preferential depletion of tangentially flying and slow particles are considered. The kinetic equation is solved for the emitter having the forms of a plane, semi-plane, strip, and circle. The average densities, flow densities, and average hydrodynamic velocities are calculated. The expressions for ionization probability of the working gas in channels of Hall thrusters are obtained.

Monte Carlo Simulation on a Neutralization Process of an Accelerated Compact Torus Plasma

A new concept of particle fueling method is proposed, and its feasibility is studied by a Monte Carlo simulation; by using a compact torus (CT) injection technique and subsequent neutralization of an accelerated CT plasma, ultrahigh-speed neutral-particle flow can be generated. The charge-exchange reaction between ions in a CT plasma and neutral particles in the neutralizer is found to work efficiently to neutralize the CT plasma within a 1-m long neutralizer in a case that the neutral gas exceeds 5 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-2</sup> torr.

Measurement of neutral flow velocity in an ECR plasma using tunable diode laser LIF spectroscopy combined with saturated absorption spectroscopy

The radial flow of neutral particles in an electron-cyclotron-resonance (ECR) argon plasma has been measured by using a newly developed high resolution laser induced fluorescence (LIF) measurement system. The flow velocity is determined by the Doppler shift of the LIF spectrum. A very high accuracy calibration of an excitation laser has been achieved by installing a saturated absorption spectroscopy unit into the LIF system. We utilized the Lamb dip, which is obtained by the saturated absorption spectroscopy, as a frequency standard for the determination of the flow velocity. The use of Lamb dip is particularly appropriate for the flow velocity measurement, since the position of Lamb dip in the frequency scale is Doppler-shift free and is not disturbed by the motion of reference medium. By utilizing the Lamb dip as the frequency standard, the reliability and stability of the laser frequency calibration is increased. From the radial measurements of LIF spectra of metastable argon atoms at the microwave power of 250 W and 5 kW, it is found that there exists an inward flow of neutral particles in the both plasmas. Both of the radial flow velocity profiles peak around 4 cm from the center, which is comparable with the radius of the boundary of the E×B rotation and anti-E×B rotation in the 5 kW discharge. The maximum flow velocity increases with the microwave power.

Heliospheric asymmetries due to the action of the interstellar magnetic field

We discuss the asymmetry of the heliospheric discontinuities obtained from the analysis of 3D modeling of the solar wind (SW) interaction with local interstellar medium (LISM). The flow of charged particles is governed by the ideal MHD equations and the flow of neutral particles is described by the Boltzmann equation. The emphasis is made on the asymmetries of the termination shock (TS) and the heliopause under the combined action of the interstellar and interplanetary magnetic fields (ISMF and IMF) in the presence of neutral hydrogen atoms whose transport through the heliosphere is modeled kinetically, using a Monte Carlo approach. We show that the deflection of neutral hydrogen flow from its original direction in the unperturbed LISM is highly anisotropic and evaluate a possible angle between the hydrogen deflection plane measured in the SOHO SWAN experiment and the plane containing the ISMF and LISM velocity vectors for different ISMF strengths. It is shown that the ISMF of a strength greater than 4 μG can account for the 10 AU difference in the TS heliocentric difference observed during its crossing by the Voyager 1 and Voyager 2 spacecraft, which however results in a larger discrepancy between the calculated and observed velocity distributions. The effect of a strong ISMF on the distribution of plasma quantities in the inner heliosheath and on 2–3 kHz radio emission is discussed.

High resolution laser induced fluorescence Doppler velocimetry utilizing saturated absorption spectroscopy

A high resolution laser induced fluorescence (LIF) system has been developed to measure the flow velocity field of neutral particles in an electron-cyclotron-resonance argon plasma. The flow velocity has been determined by the Doppler shift of the LIF spectrum, which is proportional to the velocity distribution function. Very high accuracy in velocity determination has been achieved by installing a saturated absorption spectroscopy unit into the LIF system, where the absolute value and scale of laser wavelength are determined by using the Lamb dip and the fringes of a Fabry-Perot interferometer. The minimum detectable flow velocity of a newly developed LIF system is +/-2 m/s, and this performance remains unchanged in a long-time experiment. From the radial measurements of LIF spectra of argon metastable atoms, it is found that there exists an inward flow of neutral particles associated with neutral depletion.

Simulation of Neutral Particle Flow During High Power Magnetron Impulse

The behavior of neutral component of the plasma during high power impulse magnetron sputtering was studied. Movement of the neutral particles including sputtered metal (Ti) and Ar gas during an impulse (200 µs, 1 kA, 1 kV) has been simulated using direct simulation Monte Carlo method. When the discharge current reaches kA range, very strong gas rarefaction in the main plasma region occurs and the volume density of sputtered metal exceeds the gas density several times. This may contribute to the high ratio of metal ions to Ar ions observed in experiments. Rapid gas movement in the form of a shock wave toward the substrate results in a temporary increase in density and pressure of the substrate. This again influences both the deposition flux and the discharge behavior.

ON THE AMBIPOLAR DIFFUSION AND OTHER ASYMPTOTIC LIMITS OF WEAKLY IONIZED PLASMA FLOWS

This paper reviews several different models of weakly ionized plasma flows, where charged particles are scattered in a background flow of neutral particles. A multispecies diffusion model is derived from either a kinetic model or a multifluid model (which is the Maxwellian closure of the kinetic model). This derivation is purely formal (in the sense that only the Hilbert or Chapman–Enskog expansions are established). An even simpler model, the so-called ambipolar diffusion model is derived from the multispecies diffusion model. This latter derivation is based on energy estimates and on a form of maximum principle which is established by writing the multispecies diffusion system in terms of the so-called Slotboom variables.

Development of a compact W-shaped pumped divertor in JT-60U

In JT-60U, the modification to a W-shaped pumped divertor will be completed in May 1997, aiming to realize sufficient reduction in heat flux to the targets and good H-mode confinement simultaneously. W-shaped geometry is optimized not only for forming radiative divertor plasmas and reducing the back flow of neutral particles but also for allowing various experimental configurations. Toroidally and poloidally segmented divertor plates, dome and baffles are arranged in a W-shaped poloidal configuration. The pumping speed can be changed during a shot by variable shutter valves in the three pumping ports under the outer baffle. The net throughput is enough for particle control in the steady radiative operations with high power NBI heating. Carbon fiber composite (CFC) tiles are used for the divertor targets and the divertor throat where large heat flux is expected. Gaps between two adjacent segments are carefully sealed to suppress the leak of neutral gas from the exhaust duct below the divertor and baffles. The strength of the whole structure is confirmed by an electromagnetic force analysis and structural analysis carried out for disruptions of 3 MA discharges with a halo current.

A Method for Near Field Computation of Coupled Weakly Ionized Plasma Flows in Low Earth Orbit

The problem of wake effects, particularly the near wake, from spacecraft in low Earth orbit is of increasing interest. The flow simulation reported herein combines the fully coupled effects of neutral particle flow, plasma flow, electromagnetic field effects, and spacecraft charging. The simulation necessarily allows for chemically reacting flows (associative ionization, dissociation, and chain exchange) and for thermal accommodation at a spacecraft surface. Due to the highly coupled nature of the flow physics, a full solution simultaneous approach is used. This is required due to the need for extremely high resolution results for the near wake region. In this approach, the neutral flow is modeled using a direct simulation Monte Carlo technique. The charged particles are modeled using a particle approach to solve the Poisson equation. A technique of having a separate neutral-particle grid and a charged-particle grid is used. Neutral and charged particles are allowed collisional interaction. During one time step, the neutral-particle-move process occurs separately from the charged-particle-move process which is accomplished in the presence of the electromagnetic field. A major advantage of the technique is that results may be obtained with the dominant effects of orbital flows simultaneously modeled. A major disadvantage is that the technique is computationally expensive. Flow calculations for the neutral- and charged-particle cases are compared to independent and uncoupled computational simulations to confirm their accuracy. The solution procedure and technique are presented for several types of flows at orbital altitudes of 250 and 500 km. Excellent agreement with previously verified computational algorithms has been obtained for the case of neutral particle flow and charged-particle flow. Results for the full flow simulation are presented for 250 and 500 km.

Experimental and theoretical investigation of the gas embedded Z-pinch

The paper reports observations of a sub-millimetre diameter Z-pinch discharge initiated in hydrogen gas at high pressure (0.33-2 bar) and powered by a fast rising current (dI/dt ≈ 1 kA·ns−1). The conditions for heating the pinch ohmically under pressure balance are established by using a small preheat current of short duration (5 kA, 70 ns). Measurements of the radial density profiles of the electrons in the pinch and the surrounding neutral gas are presented. The peak electron temperature in the pinch is estimated from the soft X-ray emission. The observations show that during the preheat phase, when there is no equilibrium, the plasma column expands radially and drives a shock into the neutral gas. This results in an increase of the neutral gas density in a thin layer surrounding the pinch. When the main current is applied, a pinch in radial equilibrium, with a radius of about 400 μm and peak electron density on axis (2.5 × 1024 m−3 at 0.33 bar), is observed. The estimated peak electron temperature on axis (69 eV at 0.33 bar) is about twice the Bennett temperature. An increase of the line density is observed during the equilibrium. This is ascribed to a flow of neutral particles from the high density layer surrounding the pinch column. The equilibrium is destroyed by an m = 1 instability which grows from a helical perturbation on axis. The experimental results are compared with calculations based on ideal MHD stability theory, and it is shown that the existence of a centrally peaked current density profile can be inferred from the nature of the observed instabilities. An explanation is offered for the absence of the m = 0 mode, on the basis of cooling of the outer region of the plasma.

Practical method for the purification of carrier gases for gas chromatography

For sensitive analysis of traces of inorganic gases, detectors are employed based on Penning's effect, which requires pure helium or neon as the carrier gas. These gases may be purified by an electric discharge. This method is based on cataphoresis, i.e. the change in composition of a gaseous mixture in an electric field. This change is the result of a flow of contaminant ions and is important when the ionization energy of the contaminant gas is lower than the energy of a metastable level of the carrier gas. The positive ions flow towards the cathode, which is compensated for, in the closed vessel, by a diffusive flow of neutral particles. If the electrodes are hollow and used as gas exit from the chamber, the compensating flow of neutral particles will decrease and the concentration of the contaminant in gas flowing out of the chamber through the cathode will increase. Accordingly, the concentration of the contaminant in gas flowing away through the anode becomes lower than the initial concentration. Construction of the discharge chamber and the value of the electric current depend on the initial concentration of the contaminant and the required level of purity. The experimental results show that the method may be used for the complete purification of helium and neon with low initial concentrations of contaminant. In this case, total ionization and purification can simply be obtained by a corona discharge.

An analysis of the ablation rate for solid pellets injected into neutral beam heated toroidal plasmas

A new model for calculating the ablation rate of a solid pellet injected into a neutral-beam-heated toroidal plasma is discussed. It is an extension of the neutral cloud shielding model introduced by Parks and Turnbull. Fluid equations describing a transonic stationary flow of neutral particles ablated from the pellet surface in the presence of both electron heat flux and of flux due to fast ions are derived and solved as an eigenvalue problem. – The effect of fast ions on the ablation rate is significant in low electron temperature and low density plasmas such as edge plasmas when the fast ion density is rather high. When the ablation due to fast ions is dominant and electron heat flux is negligible, the ablation rate is given by a scaling relation similar to that obtained in the case of electron heat flux only. – An example of an ablation rate profile is shown for a PDX tokamak-like plasma in a self-limiting approximation for electron temperature and density. The results are compared to those of the Milora model which includes fast ions.

Local vertical motions and kinetic temperature from AE‐C as evidence for aurora‐induced gravity waves

In situ measurements of local vertical neutral particle motions have been made using the Neutral Atmosphere Temperature Instrument (NATE) on Atmosphere Explorer‐C from observations of the direction of flow of neutral particles into the antechamber of the sensor (mass spectrometer). Values ranging from a few to more than 80 meters per second have been observed. The data show vertical motions greater than a few meters per second to be present most of the time, the magnitude being a function of many factors including magnetic activity, location, and magnetic storm history. In a specific case, it is concluded that the observed vertical motions and kinetic temperature are evidence of a travelling disturbance originating as a gravity wave in the auroral zone.

Equivalent Circuits of Rotating Plasmas

Equivalent circuits of rotating plasmas, which facilitate the understanding of their integral properties, are derived for various physical conditions. The effects of the neutral particle flow are taken into consideration for weakly-ionized plasmas, whereas for highly-ionized plasmas the viscosity effect with surrounding walls is considered. An equivalent circuit representation for “spoke-shaped” rotating plasma, which are often observed in actual experiments, are also given. The validity of the equivalent circuits, the variation of properties of the rotating plasmas due to various physical conditions and the effects of the centrifugal and Coriolis forces are discussed. The equivalent circuits derived are useful not only for the rotating plasmas but also for a wide variety of geometrical configurations of plasmas.