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Title: Low-pressure hydrogen discharge maintenance in a large-size plasma source with localized high radio-frequency power deposition

The development of the two-dimensional fluid-plasma model of a low-pressure hydrogen discharge, presented in the study, is regarding description of the plasma maintenance in a discharge vessel with the configuration of the SPIDER source. The SPIDER source, planned for the neutral-beam-injection plasma-heating system of ITER, is with localized high RF power deposition to its eight drivers (cylindrical-coil inductive discharges) and a large-area second chamber, common for all the drivers. The continuity equations for the charged particles (electrons and the three types of positive ions) and for the neutral species (atoms and molecules), their momentum equations, the energy balance equations for electrons, atoms and molecules and the Poisson equations are involved in the discharge description. In addition to the local processes in the plasma volume, the surface processes of particle reflection and conversion on the walls as well as for a heat exchange with the walls are included in the model. The analysis of the results stresses on the role of the fluxes (particle and energy fluxes) in the formation of the discharge structure. The conclusion is that the discharge behavior is completely obeyed to non-locality. The latter is displayed by: (i) maximum values of plasma parameters (charged particle densities andmore » temperatures of the neutral species) outside the region of the RF power deposition, (ii) shifted maxima of the electron density and temperature, of the plasma potential and of the electron production, (iii) an electron flux, with a vortex structure, strongly exceeding the total ion flux which gives evidence of a discharge regime of non-ambipolarity and (iv) a spatial distribution of the densities of the neutral species resulting from their fluxes.« less
Authors:
; ;  [1] ;  [2]
  1. Faculty of Physics, Sofia University, BG-1164 Sofia (Bulgaria)
  2. Department of Applied Physics, Technical University-Sofia, BG-1000 Sofia (Bulgaria)
Publication Date:
OSTI Identifier:
22423780
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 22; Journal Issue: 3; Other Information: (c) 2015 EURATOM; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; CATIONS; CONTINUITY EQUATIONS; CYLINDRICAL CONFIGURATION; ELECTRIC DISCHARGES; ELECTRON DENSITY; ELECTRON TEMPERATURE; HYDROGEN; ITER TOKAMAK; MOLECULES; NEUTRAL ATOM BEAM INJECTION; PLASMA HEATING; PLASMA POTENTIAL; POISSON EQUATION; PRESSURE RANGE KILO PA; RADIOWAVE RADIATION; REFLECTION; SPATIAL DISTRIBUTION; STRESSES; TWO-DIMENSIONAL CALCULATIONS