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Title: Observation of high energy ion tail in the SINP tokamak plasma

Abstract

The present study examines the possibility of acceleration of ions by large scale magnetohydrodynamic activities in the SINP tokamak. The analysis is done with a retarding field ion energy analyzer looking into the plasma in the tangential direction. The experiment shows the presence of high energy ions escaping the confinement zone along with the bulk low energy ions. This process seems to have a close connection with electron acceleration due to the electric field of the m/n=2/1 tearing modes.

Authors:
; ; ; ;  [1]
  1. Plasma Physics Division, Saha Institute of Nuclear Physics, 1/AF, Bidhannagar, Kolkata-700064 (India)
Publication Date:
OSTI Identifier:
20860444
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 13; Journal Issue: 12; Other Information: DOI: 10.1063/1.2404932; (c) 2006 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; ACCELERATION; ELECTRIC FIELDS; ELECTRONS; IONS; MAGNETOHYDRODYNAMICS; PLASMA; PLASMA CONFINEMENT; PLASMA DIAGNOSTICS; RADIATION TRANSPORT; SINP TOKAMAK; TEARING INSTABILITY

Citation Formats

Raychaudhuri, S., Saha, S. K., Chowdhury, S., Banik, D., and Hui, A. K.. Observation of high energy ion tail in the SINP tokamak plasma. United States: N. p., 2006. Web. doi:10.1063/1.2404932.
Raychaudhuri, S., Saha, S. K., Chowdhury, S., Banik, D., & Hui, A. K.. Observation of high energy ion tail in the SINP tokamak plasma. United States. doi:10.1063/1.2404932.
Raychaudhuri, S., Saha, S. K., Chowdhury, S., Banik, D., and Hui, A. K.. Fri . "Observation of high energy ion tail in the SINP tokamak plasma". United States. doi:10.1063/1.2404932.
@article{osti_20860444,
title = {Observation of high energy ion tail in the SINP tokamak plasma},
author = {Raychaudhuri, S. and Saha, S. K. and Chowdhury, S. and Banik, D. and Hui, A. K.},
abstractNote = {The present study examines the possibility of acceleration of ions by large scale magnetohydrodynamic activities in the SINP tokamak. The analysis is done with a retarding field ion energy analyzer looking into the plasma in the tangential direction. The experiment shows the presence of high energy ions escaping the confinement zone along with the bulk low energy ions. This process seems to have a close connection with electron acceleration due to the electric field of the m/n=2/1 tearing modes.},
doi = {10.1063/1.2404932},
journal = {Physics of Plasmas},
number = 12,
volume = 13,
place = {United States},
year = {Fri Dec 15 00:00:00 EST 2006},
month = {Fri Dec 15 00:00:00 EST 2006}
}
  • A novel method is presented to determine populations and ion energy distribution functions (IEDFs) of individual ion species having different charge states in an ion beam from the measured spectrum of an E × B probe. The inversion of the problem is performed by adopting the iterative Tikhonov regularization method with the characteristic matrices obtained from the calculated ion trajectories. In a cylindrical Hall thruster plasma, an excellent agreement is observed between the IEDFs by an E × B probe and those by a retarding potential analyzer. The existence of a high-energy tail in the IEDF is found to be mainly due to singlymore » charged Xe ions, and is interpreted in terms of non-linear ion acceleration.« less
  • Control of plasma disruption by a biased edge electrode is reported in SINP-Tokamak. The features that characterize a plasma disruption are reduced with increasing bias potential. The disruption can be completely suppressed with the concomitant stabilization of observed MHD modes that are allegedly precursors of the disruption. An m = 3/n = 1 tearing mode, which apparently causes disruption can be stabilized when a negative biasing potential is applied near the edge. These changes in the disruptive behavior with edge biasing are hypothesized to be due to changes in the current density profile.
  • The H mode in ion cyclotron-resonance-heated plasmas has been investigated with and without additional neutral beam injection. Ion cyclotron-resonance heating can cause the transition into a high-confinement regime (H mode) in combination with beam heating. The H mode, however, has also been realized: for the first time: with ion cyclotron-resonance heating alone in the D (H)-hydrogen minority scheme at an absorbed rf power of 1.1 MW.
  • The authors report on the observation of a right-handed ion/ion resonant instability in the magnetotail at 142 R{sub E}. They recorded right handed wave activity at frequencies near the proton cyclotron frequency both before and after the passage of a plasmoid. In the trailing part of the event they observed a tailward drifting beam of warm plasma, moving faster than the cold dense general tailward plasma drift. Modeling this tailward drift they conclude it could generate the observed wave activity.
  • Plasma structures, localized in the two-dimensional poloidal cross section propagating radially and poloidally, have been detected in the scrape-off layer of the SINP tokamak. Structures with densities both higher and lower than the density of the background plasma are present, with electron temperatures higher and lower, respectively, than that of the background plasma. These are responsible for the large and sporadic bursts of particle flux to the wall, amounting to 30%-40% of the total cross-field flux. These intermittent structures also cause the probability distribution function of the fluctuations to deviate from the Gaussian behavior, especially away from the limiter.