Bo Lehnert

An External Ring System for Magnetic Plasma Confinement

A new scheme for steady-state magnetic plasma confinement is suggested, consisting of a superposition of two poloidal magnetic field components. The first arises from the unidirectional currents flowing in a number of ring-shaped external conductors. The second is produced by an oppositely directed azimuthal current in the plasma. Whenever being necessary, an additional toroidal magnetic field component can be introduced. The scheme differs from those having passive guard conductors surrounding the plasma, in the sense that given currents are fed into the rings from external sources. This scheme provides a closed axisymmetric magnetic bottle with closed guiding-centre drift orbits of the plasma particles, as well as possibilities of bootstrap operation. The problems are considered of stabilizing electrostatic modes by means of minimum-average-B geometry, and of stabilizing electromagnetic modes by means of the mutual forces between the currents in the plasma and those in the external conductors.

The Partially Ionized Plasma Centrifuge

The partially ionized plasma centrifuge contains a neutral gas mixture of isotopes or elements, the motion of which is driven by a small amount of rotating plasma. The plasma motion is, in its turn, controlled by externally imposed electric and magnetic fields. In this report earlier investigations of the centrifuge are extended by an analysis of its operation conditions. It is shown that high rotational velocities, large separation degrees, and stable velocity profiles can be achieved at comparatively small power losses, within certain ranges of the parameters involved.

On the Possibilities of Plasmas Rotating at Super-critical Velocities

It is likely that the velocity limitation observed in some types of rotating plasma devices is caused by an enhanced plasma-neutral gas interaction at the end walls bounding the plasma in the magnetic field direction. If the mechanism underlying the interaction is due to some process which forms anomalous azimuthal electric fields, a short-circuit of the latter would eliminate the velocity limitation If these predictions are true, new possibilities will open up in the use of rotating plasmas. In particular, the power losses due to ions and electrons escaping from a hot isotropic plasma through the magnetic mirror ends can then be kept small enough to balance the thermonuclear power at technically realizable beta values, plasma densities, and magnetic field strengths. At the same time such a strong confinement can only be achieved by very large centrifugal forces, rotational velocities and applied voltages, the technical feasibility of which has to be further examined.

On the Interaction between a Fully lonized Plasma and a Neutral Gas Blanket

Experimental studies have been performed of a fully ionized magnetized plasma generated in a poloidal magnetic field by a transverse electric field applied between two electrodes and being surrounded by a neutral gas blanket: (i)The rotating plasma which has been generated in the crossed fields is released from its energy source and its rotation is being stopped. The plasma decay is then studied in the absence of macroscopic motions, with the exception of those from a slow diffusion process. The state of ionization is determined by suddenly giving the plasma a small pulse of angular momentum which, after a short time is recovered as a current pulse being extracted by means of a short-circuit between the electodes. The pulse becomes a measure of the state of ionization and shows that the rate of penetration of neutral gas into the plasma is strongly delayed at high plasma densities, in agreement with theory. (ii)The velocity field of a quasi-stationary, rotating plasma has been investigated spectroscopically by observing the Doppler shifts of various spectral lines. The results agree with theoretical perdictions of the velocity and temperature distributions within the plasma region. The results also support the prediction that the interior of the plasma should be screened from the surrounding neutral gas.

New Developments in Electromagnetic Field Theory

Conventional electromagnetic theory and quantum mechanics have been very successful in their applications to numerous problems in physics. Nevertheless there are questions leading to difficulties with Maxwell s equations which are not removed by and not associated with quantum mechanics. As a consequence, several new developments have been elaborated which both contribute to the understanding of so far unsolved problems, and predict new features of the electromagnetic field to exist.

Explanation of the Motionless Electromagnetic Generator with O(3) Electrodynamics

Recently, Bearden el al. developed a device which is known as a motionless electromagnetic generator (MEG) and which produces a coefficient of performance (COP) far in excess of unity. The device has been independently replicated by Naudin. In this communication, the fundamental operational principle of the MEG is explained using a version of higher symmetry electrodynamics known as O(3) electrodynamics, which is based on the empirical existence of two circular polarization states of electromagnetic radiation, and which has been developed extensively in the literature. The theoretical explanation of the MEG with O(3) electrodynamics is straightforward: Magnetic energy is taken directly ex vacua and used to replenish the permanent magnets of the MEG device, which therefore produces a source of energy that, in theory, can be replenished indefinitely from the vacuum. Such a result is incomprehensible in U(1) Maxwell-Heaviside electrodynamics.

Basic Features of EXTRAP Concept

The potentialities and properties are discussed of a recently suggested axially symmetric, quasi-steady, closed, high-beta magnetic confinement system. A toroidal pinch of non-circular cross section is immersed in the strong, inhomogeneous polodial vacuum field from a set of ring-shaped conductors, all carrying currents in the opposite direction of the plasma current. This EXTRAP concept is expected to have some important advantages, as compared to magnetic bottles based on a main torodial field component. Concerning plasma equilibrium, there are closed local and average guiding centre orbits, beta values of order unity should become available, there is no magnetic surface splitting limit, cyclotron radiation should be kept at a comparatively low level, and bootstrap operation may become possible. Concerning plasma stability, the system should not become sensitive to magnetic island formation and asymmetries, and the short magnetic connection lengths as well as the strong vacuum field gradients should favour stabilization of flute-type, kink, and other magnetohydrodynamic modes. Concerning reactor technology, high power densities are expected to be reached, superconducting coils should not become necessary, the coil stresses are moderate, and repair and replacement are facilitated by the coil geometry. Before a final judgement can be made on this concept, however, extensive experiments and further theoretical analysis are needed.

Dark energy and dark matter as due to zero point energy

An attempt is made to explain dark energy and dark matter of the expanding universe in terms of the zero point vacuum energy. This analysis is mainly limited to later stages of an observable nearly ...

On the Stabilization of Flute-type Disturbances in a Magnetized Plasma

Flute-type disturbances are investigated by normal mode analysis in the case of a low-beta plasma being confined in the field from a straight line current. A dispersion relation and stability criterion are derived including the joint effects of the plasma pressure, the finite ion Larmor radius and frequency, and of an imposed radial gravitation field. The results, which may also illustrate the general plasma behaviour in more complicated field geometries, indicate that the stability domain is enlarged substantially by finite Larmor radius effects, especially for small-scale disturbances. Also the centrifugal force in rotating plasmas should have a stabilizing effect under certain conditions. In combination with the stabilizing mechanisms in the boundary regions of impermeable plasmas, the present results provide an alternative to the method of minimum-average-B stabilization.

On Tornado Traps operated as Rotating Plasma Devices

The possibility is being discussed of creating and heating the plasma in Tornado magnetic traps by means of the rotating plasma technique. On account of the particular field geometry of these traps, it is likely that the critical velocity phenomenon of rotating plasmas can be avoided.