scholarly journals Ion charge state and energy enhancement by axial magnetic field applied during laser produced plasma expansion

2016 ◽  
Vol 34 (4) ◽  
pp. 606-614 ◽  
Author(s):  
S.A. Abbasi ◽  
A.H. Dogar ◽  
B. Ilyas ◽  
S. Ullah ◽  
M. Rafique ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Charge State ◽  
Impact Ionization ◽  
Axial Magnetic Field ◽  
Debye Length ◽  
Target Surface ◽  
Laser Wavelength ◽  
Electrostatic Model ◽  
Ion Energy ◽  
The Magnetic Field

AbstractThe effects of axial magnetic field on the properties of the ions ejected from Nd:YAG laser (wavelength = 1064 nm, pulse duration = 6 ns) produced expanding Cu plasma were investigated. A plane Cu target, without and with 0.23 T axial magnetic field at its surface, was irradiated in the fluence range of 2–24 J/cm2. The ions emitted along the target surface normal were analyzed with the help of ion collector and time-of-flight electrostatic ion energy analyzer. The integrated ion yield, highest ion charge state, average ion energy, and energy of individual ion charge states were found to increase by application of the magnetic field. The initial parameters of the non-equilibrium plasma such as average ion charge, equivalent potential, electron temperature, electron density, Debye length, and transient electric field were estimated from the experimental results obtained without and with application of the magnetic field. The increase of ion yield and ion charge state by application of magnetic field are most probably due to the trapping of electrons in front of the target surface, which boosts up the electron impact ionization process. The ion energy increment due to the magnetic field is discussed in the frame work of electrostatic model for ion acceleration in laser plasma.

scholarly journals Ion energy increase in laser-generated plasma expanding through axial magnetic field trap

2007 ◽  
Vol 25 (3) ◽  
pp. 453-464 ◽  
Author(s):  
L. Torrisi ◽  
D. Margarone ◽  
S. Gammino ◽  
L. Andò
Keyword(s):  
Magnetic Field ◽  
Electric Field ◽  
Electric Fields ◽  
Axial Magnetic Field ◽  
Ion Beam ◽  
High Vacuum ◽  
Target Surface ◽  
Axial Direction ◽  
Ion Interactions ◽  
The Magnetic Field

Laser-generated plasma is obtained in high vacuum (10−7 mbar) by irradiation of metallic targets (Al, Cu, Ta) with laser beam with intensities of the order of 1010 W/cm2. An Nd:Yag laser operating at 1064 nm wavelength, 9 ns pulse width, and 500 mJ maximum pulse energy is used. Time of flight measurements of ion emission along the direction normal to the target surface were performed with an ion collector. Measurements with and without a 0.1 Tesla magnetic field, directed along the normal to the target surface, have been taken for different target-detector distances and for increasing laser pulse intensity. Results have demonstrated that the magnetic field configuration creates an electron trap in front of the target surface along the axial direction. Electric fields inside the trap induce ion acceleration; the presence of electron bundles not only focuses the ion beam but also increases its energy, mean charge state and current. The explanation of this phenomenon can be found in the electric field modification inside the non-equilibrium plasma because of an electron bunching that increases the number of electron-ion interactions. The magnetic field, in fact, modifies the electric field due to the charge separation between the clouds of fast electrons, many of which remain trapped in the magnetic hole, and slow ions, ejected from the ablated target; moreover it increases the number of electron-ion interactions producing higher charge states.

Effects of repeated interactions and correlational disintegration on kinetic and transport properties of a non-neutral plasma in strong fields

1990 ◽  
Vol 44 (1) ◽  
pp. 167-190 ◽  
Author(s):  
Alf H. Øien
Keyword(s):  
Magnetic Field ◽  
Particle Transport ◽  
Axial Magnetic Field ◽  
Debye Length ◽  
Electron Plasma ◽  
Larmor Radius ◽  
Equilibration Time ◽  
Cylindrically Symmetric ◽  
Electric Potentials ◽  
Good Agreement

Collisions in a cylindrically symmetric non-neutral (electron) plasma, where the Larmor radius is much smaller than the Debye length, and the consequent particle transport, are studied. The plasma is confined radially by a strong axial magnetic field and axially by electric potentials. Hence two particles may interact repeatedly. Eventually they drift too far away from each other poloidally to interact any more, owing to shear in the E × B drift. The consequent build-up of correlation is limited by correlational disintegration due to collisions with ‘third particles’ between the repeated interactions. A kinetic equation including these effects is derived, and the cross-field particle transport along the density gradient is found. An associated equilibration time is shown to scale as B and to be in good agreement with the experimentally obtained values of Briscoli, Malmberg and Fine.

Nonlinear evolution of a wave packet propagating along a hot magnetoplasma column

1987 ◽  
Vol 37 (1) ◽  
pp. 107-115
Author(s):  
B. Ghosh ◽  
K. P. Das
Keyword(s):  
Magnetic Field ◽  
Multiple Scales ◽  
Nonlinear Evolution ◽  
Axial Magnetic Field ◽  
Modulational Instability ◽  
Wave Train ◽  
Dielectric Medium ◽  
Ion Effects ◽  
The Magnetic Field ◽  
Uniform Plasma

The method of multiple scales is used to derive a nonlinear Schrödinger equation, which describes the nonlinear evolution of electron plasma ‘slow waves’ propagating along a hot cylindrical plasma column, surrounded by a dielectric medium and immersed in an essentially infinite axial magnetic field. The temperature is included as well as mobile ion effects for ail possible modes of propagation along the magnetic field. From this equation the condition for modulational instability for a uniform plasma wave train is determined.

scholarly journals DC Glow Discharge in Axial Magnetic Field at Low Pressures

2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
Shen Gao ◽  
Shixiu Chen ◽  
Zengchao Ji ◽  
Wei Tian ◽  
Jun Chen
Keyword(s):  
Magnetic Field ◽  
Glow Discharge ◽  
Differential Equations ◽  
Axial Magnetic Field ◽  
Glow Discharge Plasma ◽  
Dc Glow Discharge ◽  
Fluid Approximation ◽  
Low Pressures ◽  
Physical Quantities ◽  
The Magnetic Field

On the basis of fluid approximation, an improved version of the model for the description of dc glow discharge plasma in the axial magnetic field was successfully developed. The model has yielded a set of analytic formulas for the physical quantities concerned from the electron and ion fluids equations and Poisson equation. The calculated results satisfy the practical boundary conditions. Results obtained from the model reveal that although the differential equations under the condition of axial magnetic field are consistent with the differential equations without considering the magnetic field, the solution of the equations is not completely consistent. The results show that the stronger the magnetic field, the greater the plasma density.

Design of a Dynamic Magnetic Field Steered Cathodic Arc Source in Arc Ion Plating

2011 ◽  
Vol 340 ◽  
pp. 167-172 ◽  
Author(s):  
Wen Chang Lang
Keyword(s):  
Magnetic Field ◽  
Cathode Surface ◽  
Target Surface ◽  
Target Thickness ◽  
Current Ratio ◽  
Operating Modes ◽  
Electromagnetic Coils ◽  
Cathodic Arc ◽  
Dynamic Magnetic Field ◽  
The Magnetic Field

In this work, a dynamic arched magnetic field steered arc source was deigned by virtue of Finite Element Method (FEM) calculation. The magnetic field was produced by two main electromagnetic coils so that the magnetic field can be adjusted with the help of the two currentI1and I2,whereI1is the current to the internal coil mounted coaxially in a magnetic yoke generating a static arched magnetic field to confine the cathode spots and I2is the current to the external coil mounted coaxially outside the above yoke adjusting the position of the vertex of arch. Base on the results of simulation, it was found this design enable the sweeping of the arc spots on the target surface by means of adjusting the ratio of current (I1/I2) , and cause the arc distribute evenly on the cathode surface in the diffuse arc mode transferred from the constricted arc mode. The effects of the target thickness and current ratio on the configuration and intensity of dynamic arched magnetic field were investigated. The optimized operating modes was proposed and discussed.

Schwingung eines Plasmazylinders in einem axialen Magnetfeld II

1960 ◽  
Vol 15 (3) ◽  
pp. 220-226 ◽  
Author(s):  
Klaus Körper
Keyword(s):  
Magnetic Field ◽  
Refractive Index ◽  
External Magnetic Field ◽  
Field Strength ◽  
Axial Magnetic Field ◽  
Surface Current ◽  
The Other ◽  
Plasma Cylinder ◽  
Resonance Frequencies ◽  
The Magnetic Field

Radial oscillations are excited in a homogeneous infinite plasma cylinder in a homogeneous axial magnetic field by a surface current which is homogeneous in the axial and azimuthal directions. The modes of oscillations corresponding to the axial and azimuthal components of current are not coupled, and so they may be analysed separately. The magnetic field in the plasma and vacuum is obtained, and the indices of refraction for both types of oscillations are discussed thoroughly. When the currents are parallel to the external magnetic field, the oscillations are characterized by the refractive index of Eccles. On the other hand, when the current is perpendicular to the magnetic field two resonance frequencies exist, which depend on the density of the plasma and the magnetic field strength. — In the latter case the radial characteristic oscillations of the plasma cylinder in an external magnetic field are considered.

Buoyant Convection During the Growth of Compound Semiconductors by the Liquid-Encapsulated Czochralski Process With an Axial Magnetic Field and With a Non-Axisymmetric Temperature

1996 ◽  
Vol 118 (1) ◽  
pp. 155-159 ◽  
Author(s):  
Nancy Ma ◽  
J. S. Walker
Keyword(s):  
Magnetic Field ◽  
Axial Magnetic Field ◽  
Compound Semiconductors ◽  
Vertical Axis ◽  
Crucible Wall ◽  
Buoyant Convection ◽  
Axisymmetric Part ◽  
Czochralski Process ◽  
Axisymmetric Temperature ◽  
The Magnetic Field

This paper treats the buoyant convection of a molten semiconductor in a cylindrical crucible with a vertical axis, with a uniform vertical magnetic field, and with a non-axisymmetric temperature. Most previous treatments of melt motions with vertical magnetic fields have assumed that the temperature and buoyant convection were axisymmetric. In reality, the temperature and resultant buoyant convection often deviate significantly from axisymmetry. For a given non-axisymmetric temperature, the electromagnetic suppression of the axisymmetric part of the buoyant convection is stronger than that of the non-axisymmetric part, so that the deviation from an axisymmetric melt motion increases as the magnetic field strength is increased. The non-axisymmetric part of the buoyant convection includes relatively strong azimuthal velocities adjacent to the electrically insulating vertical crucible wall, because this wall blocks the radial electric currents needed to suppress azimuthal velocities.

Anomalous temperature relaxation and particle transport in a strongly non-unifrom, fully in ionized Plasma in a stromg mangnetic field

1995 ◽  
Vol 53 (1) ◽  
pp. 31-48 ◽  
Author(s):  
Alf H. Øien
Keyword(s):  
Magnetic Field ◽  
Particle Transport ◽  
Transport Theory ◽  
Debye Length ◽  
Larmor Radius ◽  
Collision Integrals ◽  
Ion Interactions ◽  
Electrons And Ions ◽  
Temperature Relaxation ◽  
The Magnetic Field

In classical kinetic and transport theory for a fully ionized plasma in a magnetic field, collision integrals from a uniform theory without fields are used. When the magnetic field is so strong that electrons may gyrate during electron—electron and electron—ion interactions, the form of the collision integrals will be modified. Another modification will stem from strong non-uniformities transverse to the magnetic field B. Using collision terms that explicitly incorporate these effects, we derive in particular the temperature relaxation between electrons and ions and the particle transport transverse to the magnetic field. In both cases collisions between gyrating electrons, which move along the magnetic field, and non-gyrating ions, which move in arbitrary directions at a distance transverse to B from the electrons larger than the electron Larmor radius but smaller than the Debye length, give rise to enhancement factors in the corresponding classical expressions of order In (mion/mel).

Laser wavelength effects on the charge state resolved ion energy distributions from laser-produced Sn plasma

2010 ◽  
Vol 107 (4) ◽  
pp. 043303 ◽  
Author(s):  
Russell A. Burdt ◽  
Yezheng Tao ◽  
Mark S. Tillack ◽  
Sam Yuspeh ◽  
Nek M. Shaikh ◽  
...  
Keyword(s):  
Charge State ◽  
Laser Wavelength ◽  
Energy Distributions ◽  
Ion Energy ◽  
Ion Energy Distributions

Investigation of DC Vacuum Arc Interruption Ability with Combined Axial and Radial Magnetic Field

2012 ◽  
Vol 516-517 ◽  
pp. 1791-1797 ◽  
Author(s):  
Mohmmad Al Dweikat ◽  
Yu Long Huang ◽  
Xiao Lin Shen ◽  
Wei Dong Liu
Keyword(s):  
Magnetic Field ◽  
Axial Magnetic Field ◽  
Vacuum Arc ◽  
Axial Component ◽  
Circuit Breakers ◽  
Radial Magnetic Field ◽  
Vacuum Interrupter ◽  
Magnetic Field Simulation ◽  
The Magnetic Field ◽  
Field Influence

DC Vacuum Circuit Breakers based arc control has been a major topic in the last few decades. Understanding vacuum arc (VA) gives the ability to improve vacuum circuit breakers capacity. In this paper, the interaction of a DC vacuum arc with a combined Axial-Radial magnetic field was investigated. The proposed system contains an external coil to produce axial magnetic field (AMF) across the vacuum chamber. The vacuum interrupter (VI) contacts were assumed to be untreated radial magnetic field (RMF) contacts. For this purpose, Finite Element Method (FEM) based Multiphysics simulation of the immerging magnetic field influence on the VA is presented. The simulation shown the ability of the presented system to deflect high DC vacuum arc, also reveals that the vacuum arc interruption capability increases with the rise of the axial component of the magnetic field. Simulation results shown that this method can be applied to improve the interruption capability of the VI.

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