Weak Vertical Magnetic Field Research Articles

Experimental study of a toroidal magnetized plasma in the presence of a weak vertical magnetic field

Detailed measurements of density and floating potential in the poloidal cross section of a toroidal plasma with an extended source at the minor axis are presented in the first half of the paper. The second part deals with the effect of k/sub /// on curvature-induced low frequency (< omega i, the ion gyro frequency) fluctuations, where k/sub /// is the wavenumber parallel to the ambient magnetic field. The variation in k/sub /// is introduced with the help of a weak vertical magnetic field, which helps in varying the length of the toroidal magnetic field lines. We report a reduction in the fluctuation level in the presence of a weak vertical field.

On the stability of magnetized accretion discs

The shear instability of differentially rotating magnetized accretion discs is formulated as an eigenvalue problem. A monotonic instability caused by the presence of weak vertical magnetic fields, claimed by Balbus & Hawley on the basis of a local analysis, is shown to be absent whenever an azimuthal magnetic field is present. Instead the instability may take the form of overstable oscillations. A necessary condition for such an instability is obtained

The effect of a weak vertical magnetic field on the buoyancy-driven boundary-layer flow past a vertical heated wall

In this paper we investigate the effect of a weak vertical magnetic field on the boundary-layer flow of an electrically conducting fluid past a vertical heated wall. We derive similarity solutions for the flow and temperature and show that the flow is composed of three regions: an inner region where the flow is a regular perturbation of the classical boundary-layer flow due to a heated semi-infinite vertical plate; an inviscid outer region where fluid is entrained from downwards towards the plate; and beyond this a quiescent region, separated from the outer region by a free shear layer. Thus the effect of the magnetic field is to inhibit the entrainment of fluid across the magnetic field lines in the whole region and confine it to an outer boundary layer.

The effect of a weak vertical magnetic field on fluctuation-induced transport in a Bumpy-Torus plasma

Digital spectral analysis techniques are used to observe that, under the appropriate experimental conditions, the radial fluctuation-induced transport in the NASA Lewis Bumpy Torus plasma may be reversed from outward to inward by applying a weak vertical magnetic field. This reversal in the transport direction corresponds to a reversal in the sign of the phase angle between the density and potential fluctuations and results in an enhancement of the plasma density by a factor of five or more.

Inward Transport of a Toroidally Confined Plasma Subject to Strong Radial Electric Fields

The paper aims at showing that the density and confinement time of a toroidal plasma can be enhanced by radial electric fields far stronger than the ambipolar values, and that, if such electric fields point into the plasma, radially inward transport can result. The investigation deals with low-frequency fluctuation-induced transport using digitally implemented spectral analysis techniques and with the role of strong applied radial electric fields and weak vertical magnetic fields on plasma density and particle confinement times in a Bumpy Torus geometry. Results indicate that application of sufficiently strong radially inward electric fields results in radially inward fluctuation-induced transport into the toroidal electrostatic potential well; this inward transport gives rise to higher average electron densities and longer particle confinement times in the toroidal plasma.

On the steady rotation of a disc in magnetohydrodynamics

This paper gives a description of the effect of a surrounding weak vertical uniform magnetic field on the motion of a conducting fluid produced by a uniform rotation of a circular disc about its axis. It is found that a transverse magnetic field, instead of destroying the motion across the lines of force acts exactly in the opposite manner.