Showing papers by "Tadashi Sekiguchi published in 1981"
TL;DR: In this article, a nearly cylindrical column of laser-produced plasma has been generated successfully in a uniform magnetic field, where the radius of the column initially increases and then decreases (bouncing motion).
Abstract: A nearly-cylindrical column of laser-produced plasma has been generated successfully in a uniform magnetic field. The radius of the column initially increases and then decreases (bouncing motion). In the vicinity of the outer surface of this plasma column, where there is a steep density gradient with scale length shorter than the local ion Larmor radius, an azimuthal modulation appears in the plasma luminosity. This is indicative of flute-like instability with the azimuthal wave number k⊥~4×103B0.8 (in MKSA units). The dispersion equation based upon the linearized Vlasov equation with the local approsimation is derived and the occurrence of the lower-hybrid-drift instability is predicted. Fairly good agreement is found between theory and experiment.
61 citations
TL;DR: In this paper, experiments have been performed on filling a stellarator with a noncurrent-carrying laser-produced plasma stream within stellarator field, which has been found to drastically enhance the trapping efficiency of produced plasma by stellarator fields, to as high as 50 percent in contrast with the case of plasma production at one position.
Abstract: Experiments have been performed on filling a stellarator with a noncurrent-carrying laser-produced plasma Simultaneous plasma production by means of pulsed laser beams at four separate positions on the toroidal magnetic axis has been found to drastically enhance the trapping efficiency of produced plasma by stellarator field, to as high as 50 percent in contrast with about 10 percent in the case of plasma production at one position This figure of 50 percent could be further improved to nearly 75 percent by spatially isotropic plasma productions which could not be realized in the present experiments owing to technical restrictions on the stellarator employed The enhancement of trapping efficiency may be attributed to the reduction of toroidal plasma drift due to rotational transform coming into effect earlier in the multiposition production case Some approximate theoretical analyses and considerations on toroidal drift motion of laser-produced plasma stream within stellarator field have also been presented, and the theoretical prediction on these analyses appears to be consistent with experimental results obtained
5 citations
TL;DR: In this article, the behavior of spindle-cusp plasma produced at its central null-field point from a thin wire target by laser pulse is experimentally studied, mainly in a low plasma-beta regime, by means of many different plasma diagnostics.
Abstract: Behavior of a spindle-cusp plasma produced at its central null-field point from a thin wire target by laser pulse is experimentally studied, mainly in a low plasma-beta regime, by means of many different plasma diagnostics. As the results, somewhat queer confinement properties have been found, and some considerations are given for the observed results.
2 citations