Electric force on plasma ions and the momentum of the ion-neutrals flow (2025)

Enhanced momentum delivery by electric force to ions due to collisions of ions with neutrals

Physics of Plasmas, 2013

Ions in partially ionized argon, nitrogen, and helium gas discharges are accelerated across a magnetic field by an applied electric field, colliding with neutrals during the acceleration. The momentum delivered by the electric force to the ions, which is equal to the momentum carried by the mixed ion-neutral flow, is found by measuring the force exerted on a balance force meter by that flow exiting the discharge. The power deposited in the ions is calculated by measuring the ion flux and the accelerating voltage. The ratio of force over power is found for the three gases, while the gas flow rates and magnetic field intensities are varied over a wide range of values, resulting in a wide range of gas pressures and applied voltages. The measurements for the three different gases confirm our previous suggestion [G. Makrinich and A. Fruchtman, Appl. Phys. Lett. 95, 181504 (2009)] that the momentum delivered to the ions for a given power is enhanced by ion-neutral collisions during the acceleration and that this enhancement is proportional to the square root of the number of ion-neutral collisions. V

An experimental study of the ion energy balance of a magnetized plasma

Plasma Physics, 1981

We report on an experimental study of the ion energy balance of the magnetized and current-driven plasma of a hollow cathode discharge. The balance appears to be classical. At the axis of the plasma column the electron-ion Coulomb interaction is in equilibrium with the ion-neutral interaction. We find no significant influence on the energy balance by the spontaneously appearing plasma turbulence.

Magnetic field effects on gas discharge plasmas

Physics of Plasmas, 2006

A study of the fluid model for cylindrical weakly ionized quasineutral plasmas in an axial magnetic field is presented. The model takes into account ionization, ion and electron inertia, as well as frictional forces for ions and electrons. The behavior of the plasma parameters for arbitrary magnitudes of the magnetic field, arbitrary gas pressure, and plasma size is presented, making the model applicable for a wide range of discharge conditions. A magnetic field parameter is introduced, which specifies a parameter range for the magnetic field, gas pressure, and plasma size where the Boltzmann equilibrium with the ambipolar field for the electron distribution is satisfied. In addition, a parametric relation for the magnetic field, gas pressure, and plasma size is obtained, which separates the region of weak magnetic field effects from the region of strong magnetic field effects. For strongly magnetized plasmas, an asymptotic solution with nonzero plasma density at the plasma boundary...

Enhanced momentum delivery by electric force to ions due to collisions of ions with neutrals Enhanced momentum delivery by electric force to ions due to collisions of ions with neutrals

Ions in partially ionized argon, nitrogen, and helium gas discharges are accelerated across a magnetic field by an applied electric field, colliding with neutrals during the acceleration. The momentum delivered by the electric force to the ions, which is equal to the momentum carried by the mixed ion-neutral flow, is found by measuring the force exerted on a balance force meter by that flow exiting the discharge. The power deposited in the ions is calculated by measuring the ion flux and the accelerating voltage. The ratio of force over power is found for the three gases, while the gas flow rates and magnetic field intensities are varied over a wide range of values, resulting in a wide range of gas pressures and applied voltages. The measurements for the three different gases confirm our previous suggestion [G. Makrinich and A. Fruchtman, Appl. Phys. Lett. 95, 181504 (2009)] that the momentum delivered to the ions for a given power is enhanced by ion-neutral collisions during the acceleration and that this enhancement is proportional to the square root of the number of ion-neutral collisions. V C 2013 American Institute of Physics. [http://dx.

Experimental study of a radial plasma source

Physics of Plasmas, 2009

A radially outward acceleration of plasma in cylindrical geometry along an applied electric field and across an axial magnetic field is studied. We extend our investigation of the configuration, coined a Radial Plasma Source (RPS), to measurements of the plasma characteristics as functions of the gas flow rate. For specified discharge current and magnetic field the plasma flow increases and the discharge voltage decreases with an increase of the flow rate (and neutral pressure). The force exerted on a probe increases for a higher gas pressure. These measurements support the suggestion we made recently [Phys. Plasmas 16, 043507 (2009)] that the ion-neutral collisions in the acceleration region enhance the momentum delivered to the flow.

Investigation of a -discharge plasma under an increased pressure of Ar and in narrow tubes

Journal of Physics D: Applied Physics, 1998

The electrokinetic characteristics (the electron energy distribution function, the strength of the longitudinal electric field and the concentration and average energy of electrons) are measured and calculated in a (Hg + Ar)-discharge plasma under a high pressure of argon (up to 30 Torr) and in narrow tubes (the tube radius is less than 1.0 cm). A simple method of treating the second derivative of the probe current with respect to the probe potential is proposed for a straightforward way to obtain the electron energy distribution function under a high pressure of a gas. It is shown that the main assumptions on which modelling of the plasma of mercury luminescent lamps is based are also valid for the plasma in question. This leads to the existence of special similarity laws and gives a new possibility for diagnostics based on the similarity properties of the plasma. The approach proposed in the work can be easily extended to the mixtures of mercury vapour and other rare gases.

Possible mechanism for radial ion acceleration in a beam-plasma discharge

Plasma Physics Reports, 2006

A mechanism is proposed that can lead to radial ion acceleration in a plasma discharge excited by an electron beam in a relatively weak longitudinal magnetic field. The mechanism operates as follows. The beam generates an azimuthally asymmetric slow potential wave, which traps electrons. Trapped magnetized electrons drift radially with a fairly high velocity under the combined action of the azimuthal wave field (which is constant for them) and a relatively weak external longitudinal magnetic field. The radial electron flux generates a radial charge-separation electric field, which accelerates unmagnetized plasma ions in the radial direction. The ion flux densities and energies achievable in experiments with kiloelectronvolt electron beams in magnetic fields of up to 100 G are estimated.

Enhanced Plasma Transport Due To Neutral Depletion

Physical Review Letters, 2005

Formation of collisional sheath in electronegative plasma with two species of positive ions

Physics of Plasmas, 2015

Measurements of ion velocity and density in the plasma sheath

Physics of Fluids B: Plasma Physics, 1992

Using laser-induced fluorescence, the ion velocity and density inside a dc plasma sheath have been measured. A polished planar electrode, biased at -100 V, was aligned so that a laser beam struck it at normal incidence. Using this arrangement, the ion velocity component perpendicular to the electrode surface was measured. By detecting the fluorescence while scanning the laser frequency, a line shape was recorded that had two peaks, due to the Doppler shift from the incident and reflected beams. The separation of the peaks yielded an absolutely calibrated measure of the ion drift velocity, while the height of the peaks gave the ion density. As expected, in the sheath the measured ion density was lower and the velocity was higher than in this plasma. Using these measurements, it was confirmed that the ion flux is conserved in this sheath. The spatial profiles of ion velocity and density in the sheath were used to test a time-independent two-fluid theory, and good agreement was found. The data were also compared to Child's law, which showed good agreement near the electrode but predicted the density poorly, as expected, near the plasma-sheath boundary.