No abstract available

[en] The formation of field reversed configuration, FRC, in one meter mirrorless linear theta-pinch device Tupa-I was observed. This configuration was studied during the first half magnetic cycle of ringing main bank discharge using magnetic probes. The separatrix radius by the exclude flux probe and the ion temperature by visible spectroscopy were measured. The plasma dynamics was observed by the image converter camera. A clear indication of the formation of FRC due to reconnection of the antiparallel bias to the main field and a fast reconnection, less than 0.2 microsec, that is explained in terms of forced reconnection driven by the Kruskal-Schwarzschild instability, are also observed. (author)

No abstract available

[en] The formation phase of field reversed configurations (FRC) produced using a theta pinch has received considerable attention lately in connection with the possibility of developing formation methods in time scales longer than the Alven radial time, which would permit the use of low-voltage technology and represent an important engineering simplification in the trend towards larger scale machines sup (1)). The mechanisms leading to the loss of trapped reversed flux during the preheating²) and formation sup (3,4)) stages, looking for maximization of this quantity in order to improve on the stability and transport properties of the configuration in its final equilibrium state are investigated. As a result, semi-emperical scaling laws have been obtained relating the reversed flux loss with experimental operating parameters during the early stages of the formation process¹). (author)

No abstract available

[en] Silicon photodiode detectors, which have nearly flat energy response from 1 eV to 6 keV [R. Korde and L. Randall Canfield, Proc. SPIE 1140, 126 (1989)], were used as bolometers in the field reversed theta pinch experiment LSX. Plasma escaping from the field reversed configuration is naturally diverted to the ends of the vacuum enclosure. There it affects the bolometer measurements either by direct energy deposition or by emission of low energy photons. These two particle effects can be avoided by optimizing the location of the bolometers and restricting their field of view. Good agreement is observed between the silicon bolometers and a gold foil calorimeter

[en] The Grad-Hogan theory for slowly diffusing plasmas is applied to FRCs. Within this context, assuming uniform but time dependent plasma temperature, it is possible to show that the time evolution of FRCs can be described as a continuous sequence of equilibrium states, satisfying proper boundary conditions, in which the functional dependence of the pressure on the poloidal magnetic flux remains fixed. The time evolution is found by requiring that the diffusion velocity does not become singular at the 0-point. The method is applied to the Hill vortex model. (author). 11 refs, 3 figs

[en] The generation of compact torus configurations by rotating magnetic fields and linearly polarized r.f. fields is studied. In contrast to present theoretical models the investigations show that there are electron density and r.f. power thresholds where nonlinear phenomena determine the direction of d.c. current flow. (author)

[en] Published in summary form only

[en] The halo plasma, which is a thin plasma surrounding the Field Reversed Configuration (FRC), was observed in the Staged Theta Pinch-Linear (STP-L) experiment. The experimental results show that the ion flow in the halo plasma increases in opposite directions at the vicinity of the separatrix and at the edge of the halo, when the end effect is reduced by the guide field. This double structure of ion flow may be explained by the proposed model that halo plasma is formed by energetic ions shuttling between the FRC and the open field region, and the numerical results is in a good agreement with the experiment. The proposed model also suggests that the FRC has a good confinement ability for the energetic particles in the plasma does not connect with the discharge tube. (author)