scholarly journals Variations of Helicon Wave-induced Radial Plasma Transport in Different Experimental Conditions

1994 ◽  
Vol 47 (3) ◽  
pp. 315 ◽  
Author(s):  
V Petržílka
Keyword(s):  
Plasma Density ◽  
Plasma Transport ◽  
Plasma Confinement ◽  
Experimental Conditions ◽  
Magnetostatic Field ◽  
Directed Transport ◽  
Helicon Wave ◽  
Transport Velocity ◽  
Plasma Radius ◽  
Wave Induced

Variations of the helicon wave-induced radial plasma transport are presented depending on values of the plasma radius, magnetostatic field, plasma density and the frequency of the helicon wave. It is shown that the value of the helicon wave-induced transport may be significant for plasma confinement; this is demonstrated, for the experiments BASIL and SHEILA. Whereas m = +1 helicons induce an inward-directed transport and thus improve the confinement, m = -1 helicons induce an outward-directed transport velocity.

scholarly journals Chirality-dependent Plasma Density Profile Changes from Helicon Wave Ponderomotive Forces

1995 ◽  
Vol 48 (4) ◽  
pp. 691 ◽  
Author(s):  
V Petržílka ◽  
RL Dewar
Keyword(s):  
Plasma Density ◽  
Density Profile ◽  
Radial Profile ◽  
Force Density ◽  
Directed Transport ◽  
Helicon Wave ◽  
Plasma Density Profile ◽  
Ponderomotive Forces ◽  
Helicon Waves ◽  
Wave Induced

It is shown that nonresonant helicon-wave-induced transport may result in significant changes in the plasma density radial profile; this is illustrated using parameters appropriate to the cylindrical experiment BASIL and the toroidal experiment SHEILA. Whereas m = +1 helicon waves induce an inward-directed transport and change the density profile to a more centrally peaked one with a higher density on the axis, m = −1 helicon waves induce an outward-directed transport velocity and change the density profile to a hollow one. This may be the clue to the puzzle as to why m = −1 helicon waves are frequently difficult or impossible to excite, as the plasma column is effectively blown off to the discharge chamber walls by the ponderomotive force density of the waves with this chirality (sense of rotation of the wavevector with respect to the axial or toroidal magnetic field).

On helicon wave induced radial plasma transport

1993 ◽  
Vol 43 (12) ◽  
pp. 1203-1211 ◽  
Author(s):  
V. Petržílka
Keyword(s):  
Plasma Transport ◽  
Helicon Wave ◽  
Wave Induced

Standing Helicon Wave Induced by a Rapidly Bent Magnetic Field in Plasmas

2016 ◽  
Vol 116 (13) ◽  
Author(s):  
Kazunori Takahashi ◽  
Sho Takayama ◽  
Atsushi Komuro ◽  
Akira Ando
Keyword(s):  
Magnetic Field ◽  
Helicon Wave ◽  
Wave Induced

scholarly journals Theoretical aspect of enhancement and saturation in emission from laser produced plasma

2012 ◽  
Vol 30 (4) ◽  
pp. 621-631 ◽  
Author(s):  
V.N. Rai
Keyword(s):  
Laser Pulse ◽  
Plasma Density ◽  
Plasma Plume ◽  
Theoretical Aspect ◽  
Expansion Velocity ◽  
Plasma Emission ◽  
Plasma Confinement ◽  
Laser Produced Plasma ◽  
Ion Collision ◽  
Shielding Effects

AbstractThis paper presents a simplified theoretical model for the study of emission from laser produced plasma to better understand the processes and the factors involved in the onset of saturation in plasma emission as well as in increasing emission due to plasma confinement. This model considers that plasma emission is directly proportional to the square of plasma density, its volume, and the fraction of laser pulse absorbed through inverse Bremsstrahlung in the pre-formed plasma plume produced by the initial part of the laser. This shows that plasma density and temperature (that means the electron-ion collision frequency νei) decide the threshold for saturation in emission, which occurs for νei ≥ 1013 s−1, beyond which plasma shielding effects become dominant. Any decrease in plasma sound (expansion) velocity shows drastic enhancement in emission supporting the results obtained by magnetic as well as spatial confinement of laser produced plasma. The temporal evolution of plasma emission in the absence and presence of plasma confinement along with the effect of laser pulse duration are also discussed in the light of this model.

TEA CO2 Laser-Induced Plasma with a Plane Shock Wave Structure

1993 ◽  
Vol 47 (10) ◽  
pp. 1562-1566 ◽  
Author(s):  
K. Kagawa ◽  
M. Tani ◽  
H. Ueda ◽  
M. Sasaki ◽  
K. Mizukami
Keyword(s):  
Shock Wave ◽  
Laser Beam ◽  
Laser Plasma ◽  
Wave Structure ◽  
Plane Shock Wave ◽  
Plane Shock ◽  
Plasma Confinement ◽  
Time Resolved ◽  
Wave Induced ◽  
Gas Pressures

A TEA CO2 laser beam (500 mJ, 100 ns) has been focused on a Zn target at reduced ambient gas pressures. In order to confine the laser plasma into a limited space, a tube (7 × 7 × 20 mm) has been placed just in front of the target, and the laser beam has been focused through the tube on the target. The time-resolved spatial distributions of Zn emission lines show that emission intensity increases quickly with a distinct jump near the front of the plasma and that the emissions take place only in a limited thin layer. It is also shown that the displacement of the emission front is proportional to 0.6 power of time. These experimental results support the supposition that the plasma is excited by a plane shock wave induced by the laser bombardment. This laser plasma confinement technique shows the possibility of improving the sensitivity in laser microprobe spectrochemical analysis.

Collective Directional Transport of Coupled Oscillators in Symmetric Periodic Potentials

2003 ◽  
Vol 17 (22n24) ◽  
pp. 4415-4422
Author(s):  
Zhigang Zheng ◽  
Jian Gao ◽  
Gang Hu
Keyword(s):  
Coupled Oscillators ◽  
Periodic Potential ◽  
Mode Locking ◽  
Circle Map ◽  
Directed Motion ◽  
Directed Transport ◽  
Collective Transport ◽  
Periodic Potentials ◽  
Transport Velocity ◽  
Directional Transport

Collective directional transport of particles in symmetric periodic potentials is studied. An example is given to reveal the directed motion of a single particle in a symmetric periodic potential and subject to an asymmetric ac force with zero mean. It is then shown that the asymmetric coupling can give rise to a directed transport. The transport failure (pinning of the lattice) is related to the phase delocalization (crisis) in the circle map. For symmetric couplings, it is found that a train of plane wave can also lead to a directed transport. The mode-locking steps of the transport velocity is found and analyzed. The collective transport can be well optimized by adjusting parameters in the system.

On radio-frequency wave-induced radial transport and wave helicity

1993 ◽  
Vol 49 (1) ◽  
pp. 55-62 ◽  
Author(s):  
V. A. Petržílka
Keyword(s):  
Radio Frequency ◽  
Cyclotron Resonance ◽  
Ion Cyclotron Resonance ◽  
Wave Polarization ◽  
Radial Transport ◽  
Magnetostatic Field ◽  
Frequency Wave ◽  
Ion Cyclotron ◽  
Radio Frequency Wave ◽  
Wave Induced

Expressions for wave-induced radial transport are derived, allowing simple estimates to be obtained. The transport is enhanced owing to the presence of a poloidal magnetostatic field and in the vicinity of ion-cyclotron resonance. The direction of the wave-induced transport also depends on the wave polarization.

The mode transition process in collisional drift waves and self-consistent plasma diffusion across a magnetic field

1977 ◽  
Vol 55 (15) ◽  
pp. 1356-1359 ◽  
Author(s):  
R. Jones
Keyword(s):  
Magnetic Field ◽  
Transition Process ◽  
Plasma Transport ◽  
Drift Waves ◽  
Mode Transition ◽  
Linear Mode ◽  
Drift Wave ◽  
Self Consistent ◽  
Plasma Diffusion ◽  
Wave Induced

Drift wave induced cross field plasma transport is observed to destabilize new drift instabilities which then act to quench the original linear mode and enhance diffusion.

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