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Title: Concerning neutral flux shielding in the U-3M torsatron

The volume of the torsatron U-3M vacuum chamber is about 70 m{sup 3}, whereas the plasma volume is about 0.3 m{sup 3}. The large buffer volume of the chamber serves as a source of a substantial neutral flux into the U-3M plasma. A fraction of this flux falls onto the torsatron helical coils located in front of the plasma, due to which the dynamics of neutral influx into the plasma modifies. The shielding of the molecular flux from the buffer volume into the plasma is estimated using numerical calculations. Only about 10% of the incident flux reaches the plasma volume. Estimates show that about 20% of atoms escape beyond the helical coils without colliding with them. Under these conditions, the helical coils substantially affect the neutral flux. A discharge regime with a hot low-density plasma produced by a frame antenna is considered. The spatial distribution of the molecular density produced in this regime by the molecular flux from the chamber buffer volume after it has passed between the helical coils is calculated. The contributions of the fluxes emerging from the side and inner surfaces of the helical coils are considered. The calculations show that the shape of the spatial distributionmore » of the molecular density differs substantially from the shape of the magnetic surfaces.« less
Authors:
 [1]
  1. National Science Center Kharkov Institute of Physics and Technology, Institute of Plasma Physics (Ukraine)
Publication Date:
OSTI Identifier:
22472423
Resource Type:
Journal Article
Resource Relation:
Journal Name: Plasma Physics Reports; Journal Volume: 41; Journal Issue: 3; Other Information: Copyright (c) 2015 Pleiades Publishing, Ltd.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; ANTENNAS; ATOMS; MAGNET COILS; MAGNETIC SURFACES; PLASMA DENSITY; SPATIAL DISTRIBUTION; TORSATRON STELLARATORS