skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Formation of a Narrow Radial Density Profile of Fast Ions in the GDT Device

Abstract

The radial density profile of fast ions with a mean energy of 10 keV is measured in experiments with a two-component high-{beta} plasma in the GDT device. Fast ions are produced by injecting neutral beams into a warm plasma. The measured fast-ion density profile is found to be narrower than that calculated with allowance for the neutral beam trapping and Coulomb scattering. Special experiments with a movable limiter have indicated that the formation of a narrow fast-ion density profile in GDT cannot be attributed to the loss of fast ions. Possible mechanisms responsible for this effect are discussed.

Authors:
 [1];  [2]; ; ; ; ; ;  [1]
  1. Budker Institute of Nuclear Physics, Siberian Division, Russian Academy of Sciences, pr. Akademika Lavrent'eva 11, Novosibirsk, 630090 (Russian Federation)
  2. (Russian Federation)
Publication Date:
OSTI Identifier:
20718847
Resource Type:
Journal Article
Resource Relation:
Journal Name: Plasma Physics Reports; Journal Volume: 31; Journal Issue: 11; Other Information: Translated from Fizika Plazmy, ISSN 0367-2921, 31, 969-977 (No. 11, 2005); DOI: 10.1134/1.2131126; (c) 2005 Pleiades Publishing, Inc; Country of input: International Atomic Energy Agency (IAEA); TN:
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; BEAM INJECTION HEATING; COULOMB SCATTERING; HIGH-BETA PLASMA; ION DENSITY; IONS; KEV RANGE; LIMITERS; MAGNETIC MIRRORS; PLASMA BEAM INJECTION; PLASMA DENSITY; PLASMA RADIAL PROFILES; TRAPPING

Citation Formats

Prikhodko, V.V., Novosibirsk State University, ul. Pirogova 2, Novosibirsk, 630090, Anikeev, A.V., Bagryansky, P.A., Lizunov, A.A., Maximov, V.V., Murakhtin, S.V., and Tsidulko, Yu.A. Formation of a Narrow Radial Density Profile of Fast Ions in the GDT Device. United States: N. p., 2005. Web. doi:10.1134/1.2131126.
Prikhodko, V.V., Novosibirsk State University, ul. Pirogova 2, Novosibirsk, 630090, Anikeev, A.V., Bagryansky, P.A., Lizunov, A.A., Maximov, V.V., Murakhtin, S.V., & Tsidulko, Yu.A. Formation of a Narrow Radial Density Profile of Fast Ions in the GDT Device. United States. doi:10.1134/1.2131126.
Prikhodko, V.V., Novosibirsk State University, ul. Pirogova 2, Novosibirsk, 630090, Anikeev, A.V., Bagryansky, P.A., Lizunov, A.A., Maximov, V.V., Murakhtin, S.V., and Tsidulko, Yu.A. Tue . "Formation of a Narrow Radial Density Profile of Fast Ions in the GDT Device". United States. doi:10.1134/1.2131126.
@article{osti_20718847,
title = {Formation of a Narrow Radial Density Profile of Fast Ions in the GDT Device},
author = {Prikhodko, V.V. and Novosibirsk State University, ul. Pirogova 2, Novosibirsk, 630090 and Anikeev, A.V. and Bagryansky, P.A. and Lizunov, A.A. and Maximov, V.V. and Murakhtin, S.V. and Tsidulko, Yu.A.},
abstractNote = {The radial density profile of fast ions with a mean energy of 10 keV is measured in experiments with a two-component high-{beta} plasma in the GDT device. Fast ions are produced by injecting neutral beams into a warm plasma. The measured fast-ion density profile is found to be narrower than that calculated with allowance for the neutral beam trapping and Coulomb scattering. Special experiments with a movable limiter have indicated that the formation of a narrow fast-ion density profile in GDT cannot be attributed to the loss of fast ions. Possible mechanisms responsible for this effect are discussed.},
doi = {10.1134/1.2131126},
journal = {Plasma Physics Reports},
number = 11,
volume = 31,
place = {United States},
year = {Tue Nov 15 00:00:00 EST 2005},
month = {Tue Nov 15 00:00:00 EST 2005}
}
  • Studying of energy and spatial distribution of fast ions is the principal problem in GDT-based neutron source project. The analyser described here was used to solve this problem. It includes active target, stripping chamber, electrostatic capacitor and microchannel plate with amplifiers. Fast ions are neutralizing on active target (hydrogen beam). These particles go through collimation system, get recharged in the stripping chamber for further separation on energies in the electrostatic analyser and finally falls to MCP. Then signals are amplified and registered.
  • In a cold, dense, dynamically evolved cloud core that lacks embedded massive stars, the density distribution should reflect a stage of cloud evolution at the threshold of star formation. The radial density distribution in three such dense massive cores, located within two nearby regions of recent star formation, has been determined from extensive maps of two H/sub 2/CO transitions. The appearance of the maps of emission and absorption of the 2 cm line confirms the predictions of models for the excitation of this transition. Detailed models of the H/sub 2/CO radiative transport demonstrate that a rapid radial decline of density,more » rho(R)proportionalR/sup -3//sup ///sup 2/ to R/sup -2/, from a density of 10/sup 6/ cm/sup -3/ in the core to 10/sup 4/ cm/sup -3/ in the envelope, occurs over radial distances from 0.06 to 0.60 pc. These models require a decline in H/sub 2/CO abundance with increasing density in these cold cores, perhaps a result of condensation of gas onto grains. For the observed values of core radius (0.06-0.09 pc) and core mass (19-110 M/sub sun/), the H/sub 2/CO line widths indicate that the velocity dispersion due to rotation or turbulence is too small to stabilize the cloud against gravitational collapse. The observed magnetic field strength also apears to be inadequate to prevent cloud contraction and eventual star formation. The unusual 2 cm H/sub 2/CO emission toward rho Oph B is found to be spatially extended (8' x 4'). The lack of far-infrared emission from this cold dense (>10/sup 6/ cm/sup -3/) region indicates a lack of stars of high luminosity embedded within or near the surface of the cloud. The combination of cold, very dense gas in a centrally condensed region together with a lack of internal support means that within rho Oph B the stage has been set for the possible formation of one or more massive protostars.« less
  • We estimate the influence of the discrepancy of the cross sectional shapes between the magnetic flux tube and the equi-potential surface at the mirror throats of the anchor cell on the radial drift of the plug potential bounce ion. The radial potential profiles are assumed to be Gaussian. It is found that the discrepancy enhances the radial drift of the bounce ion and the spread radial potential profile moderates the enhancement. The radial potential profile of the core plasma is adjusted by controlling the electrostatic potentials of the coaxially separated end plate. It is found that the spread type ofmore » radial potential profile is effective for the retardation of the radial transport of the bounce ions.« less
  • An edge transport barrier is now one of the most important subjects of controlled fusion research. The edge transport barrier is located in the plasma region where hydrogen atoms readily penetrate, so the intensity of the H{sub {alpha}} (D{sub {alpha}}) line is high enough. A new diagnostic method uses the well-known property of hydrogen atoms that the ratio of the ionization rate S{sub i} to the excitation rate S{sub v} for the H{sub {alpha}} line is nearly constant over a wide range of plasma temperatures and densities. An expression has been derived that relates the radial profiles of the plasmamore » density and H{sub {alpha}} intensity. The use of charge coupled device detectors makes it possible to measure the radial profile of H{sub {alpha}} line intensity with a resolution {approx}0.1 cm; a high intensity of the H{sub {alpha}} line ensures a high time resolution {approx}1 ms. A high resolution is thus achieved for the density profile calculated from the H{sub {alpha}} intensity profile. The method was tested when studying the plasma density profile in the region of edge transport barrier in the L-2M stellarator. It has been shown that the density gradient varies during the barrier formation and that a fine structure of the density profile correlates with a character of the plasma transport near resonance magnetic flux surfaces.« less
  • Radial profiles of plasma parameters (such as electron temperature, plasma density and floating potential) are measured in the central cell of the Hanbit mirror device. The different shaped profiles are obtained by varying the applied magnetic field in the experiment. Thus, the relation between values of plasma beta and the slope of the profile is qualitatively investigated by using measured data obtained at different magnetic fields. In addition, the characteristics of the magnetic fluctuations (less than few ten kHz) in the experiment are investigated. The experimental investigations from the measurements at different applied magnetic fields are presented.