ヘリオトロンP磁場によるプラズマ閉じ込めの予備実験 I

概要

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A magnetic mirror field having a minimum average B configuration can be produced by the combination of an usual mirror field and the magnetic field generated by a current-carrying ring, which is put on-the midplane of the mirror field and encircles the axis. This field-configuration forms a fundamental unit of the.Heliotron-P field. The bottom of the magnetic well is on the separatrix which is the surface woven by the lines of force passing the null-field circle of this field. The plasma is axially injected into the field through a small aperture limiter near the axis or through a circular narrow slit outside the separatrix. In both cases, the injected plasma quickly fills up the magnetic well due to the flute instability. This phenomenon bears the experimental evidence of the minimum average B field. After 250 μ sec from the injection, the plasma is very quiescent and its radial density profile becomes flat across the wide region of the plasma column and it falls rapidly at the periphery. The density decays with time, keeping this profile. In this stage, the over-all decay time of the plasma density is about 500 μ sec, which corresponds to 16 times the Bohm confinement time τB. The net radial loss time is longer than 45 τB, which is inferred from direct measurements of the mirror end loss and the losses towards the ring and its supports. The electron temperature remains almost constant at 11 eV.
社団法人プラズマ・核融合学会の論文