Experimental study of fast hydromagnetic waves in an argon plasma

1964 ◽  
Vol 278 (1373) ◽  
pp. 243-255 ◽  
Keyword(s):  
Magnetic Field ◽  
Field Strength ◽  
Magnetic Field Strength ◽  
Axial Magnetic Field ◽  
Argon Plasma ◽  
Wave Number ◽  
Axially Symmetric ◽  
Plasma Parameters ◽  
Quantitative Evidence ◽  
Hydromagnetic Waves

In these experiments fast hydromagnetic waves are excited by discharging a capacitor through a single turn coil surrounding a cylindrical column of magnetized argon plasma. The plasma column is 200 cm long and 22 cm in diameter, and the axial magnetic field strength is varied in the range from 1 to 6 kG. The wave amplitude is typically 10 G, and the frequency is varied between 1.2 and 6 times the ion cyclotron frequency. Measurement of the radial variation and the relative amplitudes of the three components of the wave magnetic field shows that the oscillation is the lowest axially-symmetric mode. As predicted by the theory, the wave is elliptically polarized in the rθ plane with the magnetic vector rotating in the same sense as the electron cyclotron rotation. The experimental results demonstrate the cut-off of this mode both as the frequency is decreased and as the axial magnetic field strength is increased. Measurements of the axial wave number and absorption coefficient are in good numerical agreement with theoretical dispersion curves computed from the measured plasma parameters. This work provides quantitative evidence to support the theories currently used in treating hydromagnetic oscillations, both stable and unstable, of magnetized plasmas.

Turbulence changes from magnetic fields in a stationary plasma

2010 ◽  
Vol 77 (4) ◽  
pp. 537-545 ◽  
Author(s):  
A. B. ALEXANDER ◽  
C. T. RAYNOR ◽  
D. L. WIGGINS ◽  
M. K. ROBINSON ◽  
C. C. AKPOVO ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Field Strength ◽  
Magnetic Field Strength ◽  
Axial Magnetic Field ◽  
Turbulent Energy ◽  
Dominant Mode ◽  
Dc Glow Discharge ◽  
Turbulent Fluctuations ◽  
Stationary Plasma

AbstractWhen the krypton plasma in a DC glow discharge tube is exposed to an axial magnetic field, the turbulent energy and the characteristic dominant mode in the turbulent fluctuations are systematically and unexpectedly reduced with increasing magnetic field strength. When the index measuring the rate of transfer of energy through fluctuation scales is monitored, a lambda-like dependence on turbulent energy is routinely observed in all magnetic fields. From this, a critical turbulent energy is identified, which also decreases with increasing magnetic field strength.

scholarly journals Measurement of Some Argon Plasma Parameters Glow Discharge Under Axial Magnetic Field

2019 ◽  
Vol 7 (4) ◽  
pp. 158-166
Author(s):  
Pshtiwan M.A. Karim ◽  
Diyar S. Mayi ◽  
Shamo Kh. Al-Hakary
Keyword(s):  
Magnetic Field ◽  
Electrical Conductivity ◽  
Glow Discharge ◽  
Electron Temperature ◽  
Breakdown Voltage ◽  
Axial Magnetic Field ◽  
Argon Plasma ◽  
Emission Lines ◽  
Plasma Parameters ◽  
Gas Pressures

This paper investigates the characteristics some of argon plasma parameters of glow discharge under axial magnetic field. The DC power supply of range (0-6000) V is used as a breakdown voltage to obtain the discharge of argon gas. The discharge voltage-current (V-I) characteristic curves and Paschen’s curves as well as the electrical conductivity were studied with the presents of magnetic field confinement at different gas pressures. The magnetic field up to 25 mT was obtained using four coils of radius 6 cm and 320 turn by passing A.C current up to 5 Amperes. Spectroscopic measurements are employed for purpose of estimating two main plasma parameters electron temperature (Te) and electron density (ne). Emission spectra from positive column (PC) zone of the discharge have been studies at different values of magnetic field and pressures at constant discharge currents of 1.5 mA. Electron temperature (Te) and its density are calculated from the ratio of the intensity of two emission lines of the same lower energy levels. Experimental results show the abnormal glow region characteristics (positive resistance). Breakdown voltage versus pressure curves near the curves of paschen and decrease as magnetic field increases due to magnetic field confinement of plasma charged particles. Also the electrical conductivity increases due to enhancing magnetic field at different gas pressures. Both temperature density of electron and the intensities of two selected emission lines decrease with increasing pressure due decreasing of mean free path of electron. Electron density increase according to enhancing magnetic field, while the intensity of emitting lines tends to decrease.

An investigation of hydrodynamic waves with a cylindrical microwave resonator. III. The influence of an axial magnetic field

1969 ◽  
Vol 47 (10) ◽  
pp. 1051-1055
Author(s):  
F. L. Curzon ◽  
R. L. Pike
Keyword(s):  
Magnetic Field ◽  
Surface Wave ◽  
Field Strength ◽  
Magnetic Field Strength ◽  
Axial Magnetic Field ◽  
Microwave Resonator ◽  
Hydrodynamic Waves ◽  
Vertical Magnetic Field

A microwave resonator has been employed to study the damping of a surface wave on mercury in the presence of a vertical magnetic field. The conditions of the experiment satisfy the linearity requirements of the theory and confirm the expected dependence of the damping frequency on magnetic field strength, fluid depth, and radius.

scholarly journals Pulsar Polarization Limiting Radii and the Evolution of Pulsar Beams

1987 ◽  
Vol 125 ◽  
pp. 56-56
Author(s):  
John J. Barnard
Keyword(s):  
Magnetic Field ◽  
Field Strength ◽  
Radio Frequency ◽  
Magnetic Field Strength ◽  
Rotation Axis ◽  
Rotation Period ◽  
Position Angle ◽  
Polarization Angle ◽  
Beam Model ◽  
Plasma Parameters

We estimate the polarization limiting radius, rp1, as a function of rotation period P, magnetic field strength B, and radio frequency v, in radio pulsars assuming plasma parameters that are typical of polar-cap pair-creation models of pulsars. We find that rpl ⋍ 9 × 108(P/1s)0.4 cm, for a surface magnetic field strength of 1012 G, and radio frequency of 109 Hz. For short rotation periods, rpl approaches the light cylinder radius, rlc. Here the magnetic field becomes more azimuthal, and the excursion in position angle over a pulse is less, on average, than when rpl ≪ rlc. With the assumption of a vacuum magnetic field we calculate the polarization position angle as a function of pulse longitude, and the angles i (the angle between the magnetic moment and the rotation axis) and α (the angle between the line of sight and the rotation axis). We calculate the average change in polarization angle as a function of pulsar period, assuming a circular beam, and find consistency with the polarization data summarized by Narayan and Vivekand (1983). We conclude that the evidence is consistent with beams that are roughly constant in shape, providing an alternative to the evolving elliptical beam model of Narayan and Vivekand (1983). This interpretation is further supported by the frequency dependence of the polarization angle in the Crab Pulsar, the frequency of pulsars with double and multiple pulse components, the frequency of pulsars with interpulses, and the absence of pulsars in plerions. See Barnard (1986) for further details.

Forced Convection During Liquid Encapsulated Crystal Growth With an Axial Magnetic Field

1998 ◽  
Vol 120 (4) ◽  
pp. 844-850 ◽  
Author(s):  
Nancy Ma ◽  
John Walker ◽  
David Bliss ◽  
George Bryant
Keyword(s):  
Magnetic Field ◽  
Field Strength ◽  
Forced Convection ◽  
Magnetic Field Strength ◽  
Axial Magnetic Field ◽  
Vertical Wall ◽  
Czochralski Growth ◽  
Centripetal Acceleration ◽  
Radial Gap ◽  
The Magnetic Field

This paper treats the forced convection, which is produced by the rotation of the crystal about its vertical centerline during the liquid-encapsulated Czochralski or Kyropoulos growth of compound semiconductor crystals, with a uniform vertical magnetic field. The model assumes that the magnetic field strength is sufficiently large that convective heat transfer and all inertial effects except the centripetal acceleration are negligible. With the liquid encapsulant in the radial gap between the outside surface of the crystal and the vertical wall of the crucible, the forced convection is fundamentally different from that with a free surface between the crystal and crucible for the Czochralski growth of silicon crystals. Again unlike the case for silicon growth, the forced convection for the actual nonzero electrical conductivity of an indium-phosphide crystal is virtually identical to that for an electrically insulating crystal. The electromagnetic damping of the forced convection is stronger than that of the buoyant convection. In order to maintain a given balance between the forced and buoyant convections, the angular velocity of the crystal must be increased as the magnetic field strength is increased.

Axial magnetic field strength needed for a 126kV single break vacuum interrupter

2010 ◽  
Author(s):  
Yingyao Zhang ◽  
Yingsan Geng ◽  
Li Yu ◽  
Jing Yan ◽  
Zhiyuan Liu ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Field Strength ◽  
Magnetic Field Strength ◽  
Axial Magnetic Field ◽  
Vacuum Interrupter ◽  
Single Break
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